4mLESS24m(1) General Commands Manual
4mLESS24m(1)
1mNAME0m
less - display the contents of a file in a terminal
1mSYNOPSIS0m
1mless -?0m
1mless --help0m
1mless -V0m
1mless --version0m
1mless [-[+]aABcCdeEfFgGiIJKLmMnNqQrRsSuUVwWX~]0m
1m[-b 4m22mspace24m1m] [-h 4m22mlines24m1m] [-j
4m22mline24m1m] [-k 4m22mkeyfile24m1m]0m
1m[-{oO} 4m22mlogfile24m1m] [-p 4m22mpattern24m1m] [-P
4m22mprompt24m1m] [-t 4m22mtag24m1m]0m
1m[-T 4m22mtagsfile24m1m] [-x 4m22mtab24m1m,...] [-y
4m22mlines24m1m] [-[z] 4m22mlines24m1m]0m
1m[-# 4m22mshift24m1m] [+[+]4m22mcmd24m1m] [--]
[4m22mfilename24m1m]...0m
(See the OPTIONS section for alternate option syntax with long
option
names.)
1mDESCRIPTION0m
1mLess 22mis a program similar to 1mmore22m(1), but it has many
more features.
1mLess 22mdoes not have to read the entire input file before
starting, so
with large input files it starts up faster than text editors
like
1mvi22m(1). 1mLess 22muses termcap (or terminfo on some
systems), so it can run
on a variety of terminals. There is even limited support for
hardcopy
terminals. (On a hardcopy terminal, lines which should be printed
at
the top of the screen are prefixed with a caret.)
1mCOMMANDS0m
Commands are based on both 1mmore 22mand 1mvi22m. Commands may
be preceded by a
decimal number, called N in the descriptions below. The number is
used
by some commands, as indicated.
In the following descriptions, ^X means controlX. ESC stands
for the
ESCAPE key; for example ESCv means the two character sequence
"ES
CAPE", then "v".
h or H Help: display a summary of these commands. If you forget
all
the other commands, remember this one.
SPACE or ^V or f or ^F
Scroll forward N lines, default one window (see option -z
be
low). If N is more than the screen size, only the final
screen
ful is displayed. Warning: some systems use ^V as a
special
literalization character.
z Like SPACE, but if N is specified, it becomes the new
window
size.
ENTER or RETURN or ^N or e or ^E or j or ^J
Scroll forward N lines, default 1. The entire N lines are
dis
played, even if N is more than the screen size.
d or ^D
Scroll forward N lines, default one half of the screen size.
If
N is specified, it becomes the new default for subsequent d
and
u commands.
b or ^B or ESCv
Scroll backward N lines, default one window (see option -z
be
low). If N is more than the screen size, only the final
screen
ful is displayed.
w Like ESCv, but if N is specified, it becomes the new
window
size.
y or ^Y or ^P or k or ^K
Scroll backward N lines, default 1. The entire N lines are
dis
played, even if N is more than the screen size. Warning:
some
systems use ^Y as a special job control character.
u or ^U
Scroll backward N lines, default one half of the screen
size.
If N is specified, it becomes the new default for
subsequent d
and u commands.
J Like j, but continues to scroll beyond the end of the file.
K or Y Like k, but continues to scroll beyond the beginning of
the
file.
ESCSPACE
Like SPACE, but scrolls a full screenful, even if it reaches
the
end of the file.
ESCb Like b, but scrolls a full screenful, even if it reaches
the be
ginning of the file.
ESCj Scroll forward N file lines, default 1. A file line is a
com
plete line in the file, terminated by a newline.
ESCk Scroll backwards N file lines, default 1.
ESC) or RIGHTARROW
Scroll horizontally right N characters, default half the
screen
width (see the -# option). If a number N is specified, it
be
comes the default for future RIGHTARROW and LEFTARROW
commands.
While the text is scrolled, it acts as though the -S
option
(chop lines) were in effect.
ESC( or LEFTARROW
Scroll horizontally left N characters, default half the
screen
width (see the -# option). If a number N is specified, it
be
comes the default for future RIGHTARROW and LEFTARROW
commands.
ESC} or ^RIGHTARROW
Scroll horizontally right to show the end of the longest
dis
played line.
ESC{ or ^LEFTARROW
Scroll horizontally left back to the first column.
r or ^R or ^L
Repaint the screen.
R Repaint the screen, discarding any buffered input. That is,
re
load the current file. Useful if the file is changing while
it
is being viewed.
F Scroll forward, and keep trying to read when the end of file
is
reached. Normally this command would be used when already
at
the end of the file. It is a way to monitor the tail of a
file
which is growing while it is being viewed. (The behavior
is
similar to the "tail -f" command.) To stop waiting for
more
data, enter the interrupt character (usually ^C). On
systems
which support 1mpoll22m(2) you can also use ^X or the
character spec
ified by the --intr option. If the input is a pipe and
the
--exitfollowonclose option is in effect, 1mless
22mwill automati
cally stop waiting for data when the input side of the pipe
is
closed.
ESCF Like F, but as soon as a line is found which matches the
last
search pattern, the terminal bell is rung and forward
scrolling
stops.
g or < or ESC<
Go to line N in the file, default 1 (beginning of file).
(Warn
ing: this may be slow if N is large.)
G or > or ESC>
Go to line N in the file, default the end of the file.
(Warn
ing: this may be slow if N is large, or if N is not
specified
and standard input, rather than a file, is being read.)
ESCG Same as G, except if no number N is specified and the
input is
standard input, goes to the last line which is
currently
buffered.
p or % Go to a position N percent into the file. N should be
between 0
and 100, and may contain a decimal point.
P Go to the line containing byte offset N in the file.
{ If a left curly bracket appears in the top line displayed on
the
screen, the { command will go to the matching right
curly
bracket. The matching right curly bracket is positioned on
the
bottom line of the screen. If there is more than one left
curly
bracket on the top line, a number N may be used to specify
the
Nth bracket on the line.
} If a right curly bracket appears in the bottom line displayed
on
the screen, the } command will go to the matching left
curly
bracket. The matching left curly bracket is positioned on
the
top line of the screen. If there is more than one right
curly
bracket on the bottom line, a number N may be used to
specify
the Nth bracket on the line.
( Like {, but applies to parentheses rather than curly
brackets.
) Like }, but applies to parentheses rather than curly
brackets.
[ Like {, but applies to square brackets rather than curly
brack
ets.
] Like }, but applies to square brackets rather than curly
brack
ets.
ESC^F Followed by two characters, acts like {, but uses the two
char
acters as open and close brackets, respectively. For
example,
"ESC ^F < >" could be used to go forward to the > which
matches
the < in the top displayed line.
ESC^B Followed by two characters, acts like }, but uses the two
char
acters as open and close brackets, respectively. For
example,
"ESC ^B < >" could be used to go backward to the < which
matches
the > in the bottom displayed line.
m Followed by any lowercase or uppercase letter, marks the
first
displayed line with that letter. If the status column is
en
abled via the -J option, the status column shows the
marked
line.
M Acts like m, except the last displayed line is marked
rather
than the first displayed line.
' (Single quote.) Followed by any lowercase or uppercase
letter,
returns to the position which was previously marked with
that
letter. Followed by another single quote, returns to the
posi
tion at which the last "large" movement command was
executed.
Followed by a ^ or $, jumps to the beginning or end of the
file
respectively. Marks are preserved when a new file is
examined
within a single invocation of 1mless22m, so the ' command
can be used
to switch between input files. The --savemarks option
causes
marks to be preserved across different invocations of
1mless22m.
^X^X Same as single quote.
ESCm Followed by any lowercase or uppercase letter, clears the
mark
identified by that letter.
/pattern
Search forward in the file for the Nth line containing the
pat
tern. N defaults to 1. The pattern is a regular expression,
as
recognized by the regular expression library supplied by
your
system. By default, searching is casesensitive (uppercase
and
lowercase are considered different); the -i option can be
used
to change this. The search starts at the first line
displayed
(but see the -a and -j options, which change this).
Certain characters are special if entered at the beginning
of
the pattern; they modify the type of search rather than
become
part of the pattern:
^N or !
Search for lines which do NOT match the pattern.
^E or *
Search multiple files. That is, if the search
reaches
the END of the current file without finding a match,
the
search continues in the next file in the command
line
list.
^F or @
Begin the search at the first line of the FIRST file
in
the command line list, regardless of what is
currently
displayed on the screen or the settings of the -a or
-j
options.
^K Highlight any text which matches the pattern on the
cur
rent screen, but dont move to the first match (KEEP
cur
rent position).
^R Dont interpret regular expression metacharacters;
that
is, do a simple textual comparison.
^S Followed by a digit N between 1 and 5. Only text
which
has a nonempty match for the Nth parenthesized
SUBPAT
TERN will be considered to match the pattern. For
exam
ple, searching for "(abc)|(def)" modified with ^S1
would
search for instances of "abc", but would highlight
in
stances of both "abc" and "def". (Supported only if
1mless0m
is built with one of the regular expression
libraries
1mposix22m, 1mpcre22m, or 1mpcre222m.) Multiple
^S modifiers can be
specified, to match more than one subpattern.
^W WRAP around the current file. That is, if the
search
reaches the end of the current file without finding
a
match, the search continues from the first line of
the
current file up to the line where it started. If the
^W
modifier is set, the ^E modifier is ignored.
^L The next character is taken literally; that is, it
be
comes part of the pattern even if it is one of the
above
search modifier characters.
?pattern
Search backward in the file for the Nth line
containing the
pattern. The search starts at the last line displayed (but
see
the -a and -j options, which change this).
Certain characters are special as in the / command:
^N or !
Search for lines which do NOT match the pattern.
^E or *
Search multiple files. That is, if the search
reaches
the beginning of the current file without finding
a
match, the search continues in the previous file in
the
command line list.
^F or @
Begin the search at the last line of the last file in
the
command line list, regardless of what is currently
dis
played on the screen or the settings of the -a or -j
op
tions.
^K As in forward searches.
^R As in forward searches.
^S As in forward searches.
^W WRAP around the current file. That is, if the
search
reaches the beginning of the current file without
finding
a match, the search continues from the last line of
the
current file up to the line where it started.
^L As in forward searches.
ESC/pattern
Same as "/*".
ESC?pattern
Same as "?*".
n Repeat previous search, for Nth line containing the last
pat
tern. If the previous search was modified by ^N, the search
is
made for the Nth line NOT containing the pattern. If the
pre
vious search was modified by ^E, the search continues in
the
next (or previous) file if not satisfied in the current
file.
If the previous search was modified by ^R, the search is
done
without using regular expressions. If the previous search
was
modified by ^W, the search wraps at the end (or beginning)
of
the file. There is no effect if the previous search was
modi
fied by ^F or ^K.
N Repeat previous search, but in the reverse direction.
ESCn Repeat previous search, but crossing file boundaries.
The ef
fect is as if the previous search were modified by *.
ESCN Repeat previous search, but in the reverse direction and
cross
ing file boundaries.
ESCu Undo search highlighting. Turn off highlighting of
strings
matching the current search pattern. If highlighting is
already
off because of a previous ESCu command, turn highlighting
back
on. Any search command will also turn highlighting back
on.
(Highlighting can also be disabled by toggling the -G option;
in
that case search commands do not turn highlighting back on.)
ESCU Like ESCu but also clears the saved search pattern.
If the
status column is enabled via the -J option, this clears
all
search matches marked in the status column.
&pattern
Display only lines which match the pattern; lines which do
not
match the pattern are not displayed. If pattern is empty
(if
you type & immediately followed by ENTER), any filtering
is
turned off, and all lines are displayed. While filtering is
in
effect, an ampersand is displayed at the beginning of
the
prompt, as a reminder that some lines in the file may be
hidden.
Multiple & commands may be entered, in which case only
lines
which match all of the patterns will be displayed.
Certain characters are special as in the / command:
^N or !
Display only lines which do NOT match the pattern.
^R Dont interpret regular expression metacharacters;
that
is, do a simple textual comparison.
:e [filename]
Examine a new file. If the filename is missing, the
"current"
file (see the :n and :p commands below) from the list of
files
in the command line is reexamined. A percent sign (%)
in the
filename is replaced by the name of the current file. A
pound
sign (#) is replaced by the name of the previously
examined
file. However, two consecutive percent signs are simply
re
placed with a single percent sign. This allows you to
enter a
filename that contains a percent sign in the name.
Similarly,
two consecutive pound signs are replaced with a single
pound
sign. The filename is inserted into the command line list
of
files so that it can be seen by subsequent :n and :p
commands.
If the filename consists of several files, they are all
inserted
into the list of files and the first one is examined. If
the
filename contains one or more spaces, the entire filename
should
be enclosed in double quotes (also see the -" option).
^X^V or E
Same as :e. Warning: some systems use ^V as a special
literal
ization character. On such systems, you may not be able to
use
^V.
:n Examine the next file (from the list of files given in the
com
mand line). If a number N is specified, the Nth next
file is
examined.
:p Examine the previous file in the command line list. If a
number
N is specified, the Nth previous file is examined.
:x Examine the first file in the command line list. If a
number N
is specified, the Nth file in the list is examined.
:d Remove the current file from the list of files.
t Go to the next tag, if there were more than one matches for
the
current tag. See the -t option for more details about tags.
T Go to the previous tag, if there were more than one matches
for
the current tag.
^O^N or ^On
Search forward in the file for the Nth next OSC 8
hyperlink.
^O^P or ^Op
Search backward in the file for the Nth previous OSC 8
hyper
link.
^O^L or ^Ol
Jump to the currently selected OSC 8 hyperlink.
= or ^G or :f
Prints some information about the file being viewed,
including
its name and the line number and byte offset of the bottom
line
being displayed. If possible, it also prints the length of
the
file, the number of lines in the file and the percent of
the
file above the last displayed line.
- Followed by one of the command line option letters (see
OPTIONS
below), this will change the setting of that option and print
a
message describing the new setting. If a ^P (CONTROLP)
is en
tered immediately after the dash, the setting of the option
is
changed but no message is printed. If the option letter
has a
numeric value (such as -b or -h), or a string value (such as
-P
or -t), a new value may be entered after the option letter.
If
no new value is entered, a message describing the current
set
ting is printed and nothing is changed.
-- Like the - command, but takes a long option name (see
OPTIONS
below) rather than a single option letter. Press ENTER or
RE
TURN after typing the option name to change it. You can
enter
just the beginning of an option name, then press TAB to find
all
option names which begin with that string. A ^P immediately
af
ter the second dash suppresses printing of a message
describing
the new setting, as in the - command.
-+ Followed by one of the command line option letters this will
re
set the option to its default setting and print a message
de
scribing the new setting. (The "-+4mX24m" command does
the same
thing as "-+4mX24m" on the command line.) This does
not work for
stringvalued options.
--+ Like the -+ command, but takes a long option name rather than
a
single option letter.
-! Followed by one of the command line option letters, this
will
reset the option to the "opposite" of its default setting
and
print a message describing the new setting. This does not
work
for numeric or stringvalued options.
--! Like the -! command, but takes a long option name rather than
a
single option letter.
_ (Underscore.) Followed by one of the command line option
let
ters, this will print a message describing the current
setting
of that option. The setting of the option is not changed.
__ (Double underscore.) Like the _ (underscore) command, but
takes
a long option name rather than a single option letter. You
must
press ENTER or RETURN after typing the option name.
+cmd Causes the specified cmd to be executed each time a new file
is
examined. For example, +G causes 1mless 22mto initially
display each
file starting at the end rather than the beginning.
V Prints the version number of 1mless 22mbeing run.
q or Q or :q or :Q or ZZ
Exits 1mless22m.
The following seven commands may or may not be valid, depending on
your
particular installation.
v Invokes an editor to edit the current file being viewed.
The
editor is taken from the environment variable VISUAL if
defined,
or EDITOR if VISUAL is not defined, or defaults to "vi" if
nei
ther VISUAL nor EDITOR is defined. See also the discussion
of
LESSEDIT under the section on PROMPTS below.
! shellcommand
Invokes a shell to run the shellcommand given. A percent
sign
(%) in the command is replaced by the name of the current
file.
A pound sign (#) is replaced by the name of the previously
exam
ined file. "!!" repeats the last shell command. "!" with
no
shell command invokes an interactive shell. If a ^P
(CONTROLP)
is entered immediately after the !, no "done" message is
printed
after the shell command is executed. On Unix systems, the
shell
is taken from the environment variable SHELL, or defaults
to
"sh". On MSDOS, Windows, and OS/2 systems, the shell
is the
normal command processor.
# shellcommand
Similar to the "!" command, except that the command is
expanded
in the same way as prompt strings. For example, the name of
the
current file would be given as "%f".
| <m> shellcommand
<m> represents any mark letter. Pipes a section of the
input
file to the given shell command. The section of the file to
be
piped is between the position marked by the letter and the
cur
rent screen. The entire current screen is included,
regardless
of whether the marked position is before or after the
current
screen. <m> may also be ^ or $ to indicate beginning or end
of
file respectively. If <m> is . or newline, the current
screen
is piped. If a ^P (CONTROLP) is entered immediately after
the
mark letter, no "done" message is printed after the shell
com
mand is executed.
s filename
Save the input to a file. This works only if the input is
a
pipe, not an ordinary file.
^O^O
Run a shell command to open the URI in the current OSC 8
hyper
link, selected by a previous ^O^N or ^O^P command. To find
the
shell command, the environment variable named "LESS_OSC8_xxx"
is
read, where "xxx" is the scheme from the URI (the part
before
the first colon), or is empty if there is no colon in the
URI.
The value of the environment variable is then expanded in
the
same way as prompt strings (in particular, any instance of
"%o"
is replaced with the URI) to produce an OSC 8 "handler"
shell
command. The standard output from the handler is an
"opener"
shell command which is then executed to open the URI.
There are two special cases:
1. If the URI begins with "#", the remainder of
the
URI is taken to be the value of the id
parameter
in another OSC 8 link in the same file, and
^O^O
will simply jump to that link.
2. If the opener begins with the characters ":e"
fol
lowed by whitespace and a filename, then
instead
of running the opener as a shell command,
the
specified filename is opened in the current
in
stance of 1mless22m.
In a simple case where the opener accepts the complete URI
as a
command line parameter, the handler may be as simple as
echo mybrowser %o
In other cases, the URI may need to be modified, so the
handler
may have to do some manipulation of the %o value.
If the LESS_OSC8_xxx variable is not set, the
variable
LESS_OSC8_ANY is tried. If neither LESS_OSC8_xxx
nor
LESS_OSC8_ANY is set, links using the "xxx" scheme cannot
be
opened. However, there are default handlers for the
schemes
"man" (used when LESS_OSC8_man is not set) and "file" (used
when
LESS_OSC8_file is not set), which should work on systems
which
provide the 1msed22m(1) command and a shell with syntax
compatible
with the Bourne shell 1msh22m(1). If you use
LESS_OSC8_ANY to over
ride LESS_OSC8_file, you must set LESS_OSC8_file to "" to
indi
cate that the default value should not be used, and likewise
for
LESS_OSC8_man.
The URI passed to an OSC8 handler via %o is guaranteed not
to
contain any single quote or double quote characters, but it
may
contain any other shell metacharacters such as semicolons,
dol
lar signs, ampersands, etc. The handler should take care to
ap
propriately quote parameters in the opener command, to
prevent
execution of unintended shell commands in the case of opening
a
URI which contains shell metacharacters. Also, since the
han
dler command is expanded like a command prompt, any
metacharac
ters interpreted by prompt expansion (such as percent,
dot,
colon, backslash, etc.) must be escaped with a backslash
(see
the PROMPTS section for details).
^X When the "Waiting for data" message is displayed, such as
while
in the F command, pressing ^X will stop 1mless 22mfrom
waiting and
return to a prompt. This may cause 1mless 22mto think
that the file
ends at the current position, so it may be necessary to use
the
R or F command to see more data. The --intr option can be
used
to specify a different character to use instead of ^X.
This
command works only on systems that support the 1mpoll22m(2)
function.
On systems without 1mpoll22m(2), the interrupt character
(usually ^C)
can be used instead.
1mOPTIONS0m
Command line options are described below. Most options may be
changed
while 1mless 22mis running, via the "-" command.
Some options may be given in one of two forms: either a dash
followed
by a single letter, or two dashes followed by a long option name.
A
long option name may be abbreviated as long as the abbreviation is
un
ambiguous. For example, --mouse may be abbreviated --mou, but
not
--mo, since both --mouse and --modelines begin with --mo. Some
long
option names are in uppercase, such as --QUITATEOF, as
distinct from
--quitateof. Such option names need only have their first
letter
capitalized; the remainder of the name may be in either case. For
ex
ample, --Quitateof is equivalent to --QUITATEOF.
Options are also taken from the environment variable "LESS". For
exam
ple, to avoid typing "less -options ..." each time 1mless 22mis
invoked, you
might tell 1mcsh22m:
setenv LESS "-options"
or if you use 1msh22m:
LESS="-options"; export LESS
On MSDOS and Windows, you dont need the quotes, but you
should be
careful that any percent signs in the options string are not
inter
preted as an environment variable expansion.
The environment variable is parsed before the command line, so
command
line options override the LESS environment variable. If an option
ap
pears in the LESS variable, it can be reset to its default value on
the
command line by beginning the command line option with "-+".
Some options like -k or -D require a string to follow the option
let
ter. The string for that option is considered to end when a
dollar
sign ($) is found. For example, you can set two -D options like
this:
LESS="Dnwb$Dsbw"
If the --usebackslash option appears earlier in the options,
then a
dollar sign or backslash may be included literally in an option
string
by preceding it with a backslash. If the --usebackslash option
is not
in effect, then backslashes are not treated specially, and there is
no
way to include a dollar sign in the option string.
-? or --help
This option displays a summary of the commands accepted by
1mless0m
(the same as the h command). (Depending on how your shell
in
terprets the question mark, it may be necessary to quote
the
question mark, thus: "-?".)
-a or --searchskipscreen
By default, forward searches start at the top of the
displayed
screen and backwards searches start at the bottom of the
dis
played screen (except for repeated searches invoked by the n
or
N commands, which start after or before the "target" line
re
spectively; see the -j option for more about the target
line).
The -a option causes forward searches to instead start at
the
bottom of the screen and backward searches to start at the
top
of the screen, thus skipping all lines displayed on the
screen.
-A or --SEARCHSKIPSCREEN
Causes all forward searches (not just nonrepeated
searches) to
start just after the target line, and all backward searches
to
start just before the target line. Thus, forward searches
will
skip part of the displayed screen (from the first line up to
and
including the target line). Similarly backwards searches
will
skip the displayed screen from the last line up to and
including
the target line. This was the default behavior in less
versions
prior to 441.
-b4mn24m or --buffers=4mn0m
Specifies the amount of buffer space 1mless 22mwill
use for each
file, in units of kilobytes (1024 bytes). By default 64 KB
of
buffer space is used for each file (unless the file is a
pipe;
see the -B option). The -b option specifies instead that
4mn0m
kilobytes of buffer space should be used for each file. If
4mn24m is
-1, buffer space is unlimited; that is, the entire file can
be
read into memory.
-B or --autobuffers
By default, when data is read from a pipe, buffers are
allocated
automatically as needed. If a large amount of data is read
from
the pipe, this can cause a large amount of memory to be
allo
cated. The -B option disables this automatic allocation
of
buffers for pipes, so that only 64 KB (or the amount of
space
specified by the -b option) is used for the pipe. Warning:
use
of -B can result in erroneous display, since only the most
re
cently viewed part of the piped data is kept in memory; any
ear
lier data is lost. Lost characters are displayed as
question
marks.
-c or --clearscreen
Causes full screen repaints to be painted from the top
line
down. By default, full screen repaints are done by
scrolling
from the bottom of the screen.
-C or --CLEARSCREEN
Same as -c, for compatibility with older versions of
1mless22m.
-d or --dumb
The -d option suppresses the error message normally displayed
if
the terminal is dumb; that is, lacks some important
capability,
such as the ability to clear the screen or scroll backward.
The
-d option does not otherwise change the behavior of
1mless 22mon a
dumb terminal.
-D1mx4m22mcolor24m or --color=1mx4m22mcolor0m
Changes the color of different parts of the displayed text.
1mx0m
is a single character which selects the type of text whose
color
is being set:
B Binary characters.
C Control characters.
E Errors and informational messages.
H Header lines and columns, set via the --header option.
M Mark letters in the status column.
N Line numbers enabled via the -N option.
P Prompts.
R The rscroll character.
S Search results.
W The highlight enabled via the -w option.
15 The text in a search result which matches the
first
through fifth parenthesized subpattern.
Subpattern
coloring works only if 1mless 22mis built with one
of the reg
ular expression libraries 1mposix22m, 1mpcre22m,
or 1mpcre222m.
d Bold text.
k Blinking text.
s Standout text.
u Underlined text.
The uppercase letters and digits can be used only when
the
--usecolor option is enabled. When text color is
specified by
both an uppercase letter and a lowercase letter, the
uppercase
letter takes precedence. For example, error messages are
nor
mally displayed as standout text. So if both "s" and "E"
are
given a color, the "E" color applies to error messages, and
the
"s" color applies to other standout text. The lowercase
letters
refer to bold and underline text formed by overstriking
with
backspaces (see the -U option) and to noncontent text
(such as
line numbers and prompts), but not to text formatted using
ANSI
escape sequences with the -R option (but see the note below
for
different behavior on Windows and MSDOS).
A lowercase letter may be followed by a + to indicate that
the
normal format change and the specified color should both
be
used. For example, -Dug displays underlined text as green
with
out underlining; the green color has replaced the usual
under
line formatting. But -Du+g displays underlined text as
both
green and in underlined format.
4mcolor24m is either a 4bit color string or an 8bit
color string:
A 4bit color string is one or two characters, where the
first
character specifies the foreground color and the second
speci
fies the background color as follows:
b Blue
c Cyan
g Green
k Black
m Magenta
r Red
w White
y Yellow
The corresponding uppercase letter denotes a brighter shade
of
the color. For example, -DNGk displays line numbers as
bright
green text on a black background, and -DEbR displays error
mes
sages as blue text on a bright red background. If either
char
acter is a "" or is omitted, the corresponding color is
set to
that of normal text.
An 8bit color string is one or two decimal integers
separated
by a dot, where the first integer specifies the foreground
color
and the second specifies the background color. Each integer
is
a value between 0 and 255 inclusive which selects a "CSI
38;5"
color value
(see
https://en.wikipedia.org/wiki/ANSI_escape_code#SGR). If
either
integer is a "" or is omitted, the corresponding color
is set
to that of normal text.
A 4bit or 8bit color string may be followed by one or
more of
the following characters to set text attributes in addition
to
the color.
s or Standout (reverse video)
u or _ Underline
d or * Bold
l or & Blinking
On MSDOS and Windows, the --color option behaves
differently
from what is described above in these ways:
The bold (d and *) and blinking (l and &) text
attributes
at the end of a color string are not supported.
Lowercase color selector letters refer to text
formatted
by ANSI escape sequences with -R, in addition to
over
struck and noncontent text (but see -Da).
For historical reasons, when a lowercase color
selector
letter is followed by a numeric color value, the
number
is not interpreted as an "CSI 38;5" color value as
de
scribed above, but instead as a
4bit
CHAR_INFO.Attributes value, between 0 and 15
inclusive
(see
https://learn.microsoft.com/en
us/windows/console/charinfostr).
To avoid confusion, it is recommended that the
equivalent
letters rather than numbers be used after a
lowercase
color selector on MSDOS/Windows.
Numeric color values ("CSI 38;5" color) following an
up
percase color selector letter are not supported on
sys
tems earlier than Windows 10.
Only a limited set of ANSI escape sequences to set
color
in the content work correctly. 4bit color
sequences
work, but "CSI 38;5" color sequences do not.
The -Da option makes the behavior of --color more
similar
to its behavior on nonMSDOS/Windows systems by
(1) mak
ing lowercase color selector letters not affect text
for
matted with ANSI escape sequences, and (2) allowing
"CSI
38;5" color sequences in the content work by passing
them
to the terminal (only on Windows 10 and later; on
earlier
Windows systems, such sequences do not work regardless
of
the setting of -Da).
-e or --quitateof
Causes 1mless 22mto automatically exit the second time
it reaches
endoffile. By default, the only way to exit 1mless
22mis via the
"q" command.
-E or --QUITATEOF
Causes 1mless 22mto automatically exit the first time it
reaches end
offile.
-f or --force
Forces nonregular files to be opened. (A nonregular
file is a
directory or a device special file.) Also suppresses the
warn
ing message when a binary file is opened. By default,
1mless 22mwill
refuse to open nonregular files. Note that some operating
sys
tems will not allow directories to be read, even if -f is
set.
-F or --quitifonescreen
Causes 1mless 22mto automatically exit if the entire file
can be dis
played on the first screen. Also see the description of
the
LESS_SHELL_LINES environment variable below.
-g or --hilitesearch
Normally, 1mless 22mwill highlight ALL strings which
match the last
search command. The -g option changes this behavior to
high
light only the particular string which was found by the
last
search command. This can cause 1mless 22mto run somewhat
faster than
the default.
-G or --HILITESEARCH
The -G option suppresses all highlighting of strings found
by
search commands.
-h4mn24m or --maxbackscroll=4mn0m
Specifies a maximum number of lines to scroll backward. If
it
is necessary to scroll backward more than 4mn24m lines, the
screen is
repainted in a forward direction instead. (If the terminal
does
not have the ability to scroll backward, -h0 is implied.)
-i or --ignorecase
Causes searches to ignore case; that is, uppercase and
lowercase
are considered identical. This option is ignored if any
upper
case letters appear in the search pattern; in other words,
if a
pattern contains uppercase letters, then that search does
not
ignore case.
-I or --IGNORECASE
Like -i, but searches ignore case even if the pattern
contains
uppercase letters.
-j4mn24m or --jumptarget=4mn0m
Specifies a line on the screen where the "target" line is to
be
positioned. The target line is the line specified by any
com
mand to search for a pattern, jump to a line number, jump to
a
file percentage or jump to a tag. The screen line may be
speci
fied by a number: the top line on the screen is 1, the next
is
2, and so on. The number may be negative to specify a line
rel
ative to the bottom of the screen: the bottom line on the
screen
is -1, the second to the bottom is -2, and so on.
Alternately,
the screen line may be specified as a fraction of the height
of
the screen, starting with a decimal point: .5 is in the
middle
of the screen, .3 is three tenths down from the first line,
and
so on. If the line is specified as a fraction, the actual
line
number is recalculated if the terminal window is resized.
If
the --header option is used and the target line specified by
-j
would be obscured by the header, the target line is moved to
the
first line after the header.
If any form of the -j option is used, repeated forward
searches
(invoked with "n" or "N") begin at the line immediately
after
the target line, and repeated backward searches begin at
the
target line, unless changed by -a or -A. For example, if
"-j4"
is used, the target line is the fourth line on the screen,
so
forward searches begin at the fifth line on the screen.
However
nonrepeated searches (invoked with "/" or "?") always begin
at
the start or end of the current screen respectively.
-J or --statuscolumn
Displays a status column at the left edge of the screen.
The
character displayed in the status column may be one of:
> The line is chopped with the -S option, and the text
that
is chopped off beyond the right edge of the screen
con
tains a match for the current search.
< The line is horizontally shifted, and the text that
is
shifted beyond the left side of the screen contains
a
match for the current search.
= The line is both chopped and shifted, and there
are
matches beyond both sides of the screen.
* There are matches in the visible part of the line
but
none to the right or left of it.
az, AZ
The line has been marked with the corresponding
letter
via the m or M command.
-k4mfilename24m or --lesskeyfile=4mfilename0m
Causes 1mless 22mto open and interpret the named file as a
1mlesskey22m(1)
binary file. Multiple -k options may be specified. If
the
LESSKEY or LESSKEY_SYSTEM environment variable is set, or
if a
lesskey file is found in a standard place (see KEY BINDINGS),
it
is also used as a 1mlesskey 22mfile. Note the
warning under
"--lesskeycontent" below.
--lesskeysrc=4mfilename0m
Causes 1mless 22mto open and interpret the named file as a
1mlesskey22m(1)
source file. If the LESSKEYIN or LESSKEYIN_SYSTEM
environment
variable is set, or if a lesskey source file is found in a
stan
dard place (see KEY BINDINGS), it is also used as a
lesskey
source file. Prior to version 582, the 1mlesskey
22mprogram needed
to be run to convert a lesskey 4msource24m file to a
lesskey 4mbinary0m
file for 1mless 22mto use. Newer versions of 1mless
22mread the lesskey
source file directly and ignore the binary file if the
source
file exists. Note the warning under "--lesskeycontent"
below.
--lesskeycontent=4mtext0m
Causes 1mless 22mto interpret the specified text as the
contents of a
1mlesskey22m(1) source file. In the text, 1mlesskey
22mlines may be sepa
rated by either newlines as usual, or by semicolons. A
literal
semicolon may be represented by a backslash followed by a
semi
colon.
Warning: certain environment variables such as LESS,
LESSSECURE,
LESSCHARSET and others, which are used early in startup,
cannot
be set in a file specified by a command line option (--
lesskey,
--lesskeysrc or --lesskeycontent). When using a
1mlesskey 22mfile
to set environment variables, it is safer to use the
default
lesskey file, or to specify the file using the LESSKEYIN
or
LESSKEY_CONTENT environment variables rather than using a
com
mand line option.
-K or --quitonintr
Causes 1mless 22mto exit immediately (with status 2) when
an inter
rupt character (usually ^C) is typed. Normally, an
interrupt
character causes 1mless 22mto stop whatever it is doing and
return to
its command prompt. Note that use of this option makes it
im
possible to return to the command prompt from the "F"
command.
-L or --nolessopen
Ignore the LESSOPEN environment variable (see the INPUT
PRE
PROCESSOR section below). This option can be set from
within
1mless22m, but it will apply only to files opened
subsequently, not
to the file which is currently open.
-m or --longprompt
Causes 1mless 22mto prompt verbosely (like 1mmore22m(1)),
with the percent
into the file. By default, 1mless 22mprompts with a colon.
-M or --LONGPROMPT
Causes 1mless 22mto prompt even more verbosely than
1mmore22m(1).
-n or --linenumbers
Suppresses line numbers. The default (to use line numbers)
may
cause 1mless 22mto run more slowly in some cases,
especially with a
very large input file. Using line numbers means: the line
num
ber will be displayed in the verbose prompt and in the =
com
mand, and the v command will pass the current line number to
the
editor (see also the discussion of LESSEDIT in PROMPTS
below).
-N or --LINENUMBERS
Causes a line number to be displayed at the beginning of
each
line in the display.
-o4mfilename24m or --logfile=4mfilename0m
Causes 1mless 22mto copy its input to the named file as it
is being
viewed. This applies only when the input file is a pipe, not
an
ordinary file. If the file already exists, 1mless
22mwill ask for
confirmation before overwriting it.
-O4mfilename24m or --LOGFILE=4mfilename0m
The -O option is like -o, but it will overwrite an existing
file
without asking for confirmation.
If no log file has been specified, the -o and -O options can
be
used from within 1mless 22mto specify a log file.
Without a file
name, they will simply report the name of the log file. The
"s"
command is equivalent to specifying -o from within
1mless22m.
-p4mpattern24m or --pattern=4mpattern0m
The -p option on the command line is equivalent to
specifying
+/4mpattern24m; that is, it tells 1mless 22mto start at
the first occur
rence of 4mpattern24m in the file.
-P4mprompt24m or --prompt=4mprompt0m
Provides a way to tailor the three prompt styles to your
own
preference. This option would normally be put in the LESS
envi
ronment variable, rather than being typed in with each
1mless 22mcom
mand. Such an option must either be the last option in the
LESS
variable, or be terminated by a dollar sign.
-Ps followed by a string changes the default (short) prompt
to
that string.
-Pm changes the medium (-m) prompt.
-PM changes the long (-M) prompt.
-Ph changes the prompt for the help screen.
-P= changes the message printed by the = command.
-Pw changes the message printed while waiting for data (in
the
"F" command).
All prompt strings consist of a sequence of letters and
special
escape sequences. See the section on PROMPTS for more
details.
-q or --quiet or --silent
Causes moderately "quiet" operation: the terminal bell is
not
rung if an attempt is made to scroll past the end of the file
or
before the beginning of the file. If the terminal has a
"visual
bell", it is used instead. The bell will be rung on
certain
other errors, such as typing an invalid character. The
default
is to ring the terminal bell in all such cases.
-Q or --QUIET or --SILENT
Causes totally "quiet" operation: the terminal bell is
never
rung. If the terminal has a "visual bell", it is used in
all
cases where the terminal bell would have been rung.
-r or --rawcontrolchars
Causes "raw" control characters to be displayed. The default
is
to display control characters using the caret notation; for
ex
ample, a controlA (octal 001) is displayed as "^A" (with
some
exceptions as described under the -U option). Warning: when
the
-r option is used, 1mless 22mcannot keep track of the
actual appear
ance of the screen (since this depends on how the screen
re
sponds to each type of control character). Thus, various
dis
play problems may result, such as long lines being split in
the
wrong place.
USE OF THE -r OPTION IS DANGEROUS AND IS NOT RECOMMENDED.
The -r option can be set on the command line or via the -
com
mand, but to avoid unintentional use, it cannot be set in a
LESS
environment variable. If -r appears in a LESS environment
vari
able, it is treated as if it were -R.
-R or --RAWCONTROLCHARS
Like -r, but only a limited set of escape sequences are
output
in "raw" form. Unlike -r, the screen appearance is
maintained
correctly. The sequences which are output raw are:
1. ANSI SGR ("color") sequences
2. OSC 8 hyperlinks
3. Other OSC sequences, if the OSC type number is listed in
the
LESSANSIOSCALLOW environment variable
4. OSC sequences starting with a nonstandard introductory
char
acter (that is, something other than "]"), if the character
is
listed in the LESSANSIOSCCHARS environment variable followed
by
an asterisk
ANSI color escape sequences are sequences of the form:
ESC [ ... m
where the "..." is zero or more color specification
characters.
Color escape sequences are only supported when the color
is
changed within one line, not across lines. In other words,
the
beginning of each line is assumed to be normal
(noncolored),
regardless of any escape sequences in previous lines.
You can make 1mless 22mthink that characters other than
"m" can end
ANSI color escape sequences by setting the environment
variable
LESSANSIENDCHARS to the list of characters which can end a
color
escape sequence. And you can make 1mless 22mthink that
characters
other than the standard ones may appear between the ESC and
the
m by setting the environment variable LESSANSIMIDCHARS to
the
list of characters which can appear.
OSC sequences are of the form:
ESC ] N ; ... 7
where the OSC type number N is a decimal integer. The
terminat
ing sequence may be either a BEL character (7) as above, or
the
twocharacter sequence "ESC
-s or --squeezeblanklines
Causes consecutive blank lines to be squeezed into a
single
blank line. This is useful when viewing 1mnroff22m(1)
output.
-S or --choplonglines
Causes lines longer than the screen width to be chopped
(trun
cated) rather than wrapped. That is, the portion of a long
line
that does not fit in the screen width is not displayed until
you
press RIGHTARROW. The default is to wrap long lines; that
is,
display the remainder on the next line. See also the --
wordwrap
option. While the --header option is active, the -S option
is
ignored, and lines longer than the screen width are
truncated.
-t4mtag24m or --tag=4mtag0m
The -t option, followed immediately by a TAG, will edit the
file
containing that tag. For this to work, tag information must
be
available; for example, there may be a file in the current
di
rectory called "tags", which was previously built by
1mctags22m(1) or
an equivalent command. If the environment variable
LESSGLOBALT
AGS is set, it is taken to be the name of a command
compatible
with 1mglobal22m(1), and that command is executed to
find the tag.
(See http://www.gnu.org/software/global/global.html). The
-t
option may also be specified from within 1mless 22m(using
the - com
mand) as a way of examining a new file. The command ":t"
is
equivalent to specifying -t from within 1mless22m.
-T4mtagsfile24m or --tagfile=4mtagsfile0m
Specifies a tags file to be used instead of "tags".
-u or --underlinespecial
Causes backspaces and carriage returns to be treated as
print
able characters; that is, they are sent to the terminal
when
they appear in the input.
-U or --UNDERLINESPECIAL
Causes backspaces, tabs, carriage returns and "formatting
char
acters" (as defined by Unicode) to be treated as control
charac
ters; that is, they are handled as specified by the -r
option.
By default, if neither -u nor -U is given, backspaces which
ap
pear adjacent to an underscore character are treated
specially:
the underlined text is displayed using the terminals
hardware
underlining capability. Also, backspaces which appear
between
two identical characters are treated specially: the
overstruck
text is printed using the terminals hardware boldface
capabili
ty. Other backspaces are deleted, along with the
preceding
character. Carriage returns immediately followed by a
newline
are deleted. Other carriage returns are handled as specified
by
the -r option. Unicode formatting characters, such as the
Byte
Order Mark, are sent to the terminal. Text which is
overstruck
or underlined can be searched for if neither -u nor -U is in
ef
fect.
See also the --procbackspace, --proctab, and --
procreturn op
tions.
-V or --version
Displays the version number of 1mless22m.
-w or --hiliteunread
Temporarily highlights the first "new" line after a
forward
movement of a full page. The first "new" line is the line
imme
diately following the line previously at the bottom of
the
screen. Also highlights the target line after a g or p
command.
The highlight is removed at the next command which causes
move
ment. If the --statusline option is in effect, the entire
line
(the width of the screen) is highlighted. Otherwise, only
the
text in the line is highlighted, unless the -J option is in
ef
fect, in which case only the status column is highlighted.
-W or --HILITEUNREAD
Like -w, but temporarily highlights the first new line after
any
forward movement command larger than one line.
-x4mn24m,... or --tabs=4mn24m,...
Sets tab stops. If only one 4mn24m is specified, tab stops
are set
at multiples of 4mn24m. If multiple values separated by
commas are
specified, tab stops are set at those positions, and then
con
tinue with the same spacing as the last two. For
example,
"x9,17" will set tabs at positions 9, 17, 25, 33, etc.
The de
fault for 4mn24m is 8.
-X or --noinit
Disables sending the termcap initialization and
deinitialization
strings to the terminal. This is sometimes desirable if
the
deinitialization string does something unnecessary, like
clear
ing the screen.
-y4mn24m or --maxforwscroll=4mn0m
Specifies a maximum number of lines to scroll forward. If it
is
necessary to scroll forward more than 4mn24m lines, the
screen is re
painted instead. The -c or -C option may be used to
repaint
from the top of the screen if desired. By default, any
forward
movement causes scrolling.
-z4mn24m or --window=4mn24m or -4mn0m
Changes the default scrolling window size to 4mn24m lines.
The de
fault is one screenful. The z and w commands can also be
used
to change the window size. The "z" may be omitted for
compati
bility with some versions of 1mmore22m(1). If the number
4mn24m is nega
tive, it indicates 4mn24m lines less than the current
screen size.
For example, if the screen is 24 lines, 4m-z-424m sets the
scrolling
window to 20 lines. If the screen is resized to 40 lines,
the
scrolling window automatically changes to 36 lines.
-"4mcc24m or --quotes=4mcc0m
Changes the filename quoting character. This may be
necessary
if you are trying to name a file which contains both spaces
and
quote characters. Followed by a single character, this
changes
the quote character to that character. Filenames containing
a
space should then be surrounded by that character rather than
by
double quotes. Followed by two characters, changes the
open
quote to the first character, and the close quote to the
second
character. Filenames containing a space should then be
preceded
by the open quote character and followed by the close
quote
character. Note that even after the quote characters
are
changed, this option remains -" (a dash followed by a
double
quote).
-~ or --tilde
Normally lines after end of file are displayed as a single
tilde
(~). This option causes lines after end of file to be
displayed
as blank lines.
-# or --shift
Specifies the default number of positions to scroll
horizontally
in the RIGHTARROW and LEFTARROW commands. If the number
speci
fied is zero, it sets the default number of positions to
one
half of the screen width. Alternately, the number may be
speci
fied as a fraction of the width of the screen, starting with
a
decimal point: .5 is half of the screen width, .3 is
three
tenths of the screen width, and so on. If the number is
speci
fied as a fraction, the actual number of scroll positions is
re
calculated if the terminal window is resized.
--cmd=4mcommands0m
The specified string is taken to be an initial command to
1mless22m.
This is similar to specifying "+4mcommands24m", except that
commands
specified by --cmd are not executed if 1mless 22mexits
immediately
due to the use of the -E or -F option, while commands
specified
by the 1m+ 22moption are executed even if 1mless 22mexits
immediately.
--exitfollowonclose
When using the "F" command on a pipe, 1mless 22mwill
automatically
stop waiting for more data when the input side of the pipe
is
closed.
--filesize
If --filesize is specified, 1mless 22mwill determine the
size of the
file immediately after opening the file. Then the "="
command
will display the number of lines in the file. Normally this
is
not done, because it can be slow if the input file is
nonseek
able (such as a pipe) and is large.
--followname
Normally, if the input file is renamed while an F command is
ex
ecuting, 1mless 22mwill continue to display the contents of
the orig
inal file despite its name change. If --followname is
speci
fied, during an F command 1mless 22mwill periodically
attempt to re
open the file by name. If the reopen succeeds and the file
is a
different file from the original (which means that a new
file
has been created with the same name as the original (now
re
named) file), 1mless 22mwill display the contents of that
new file.
--formfeed
When scrolling forward or backward in the file, stop if a
line
beginning with a form feed character (^L) is reached. This
can
be useful when viewing a file which uses form feeds
between
pages.
--header=4mL24m,4mC24m,4mN0m
Sets the number of header lines and columns displayed on
the
screen. The number of header lines is set to 4mL24m. If
4mL24m is 0,
header lines are disabled. If 4mL24m is empty or missing,
the number
of header lines is unchanged. The number of header columns
is
set to 4mC24m. If 4mC24m is 0, header columns are
disabled. If 4mC24m is emp
ty or missing, the number of header columns is unchanged.
The
first header line is set to line number 4mN24m in the
file. If 4mN24m is
empty or missing, it is taken to be the number of the line
cur
rently displayed in the first line of the screen (if the --
head
er command has been issued from within 1mless22m), or
1 (if the
--header option has been given on the command line). The
spe
cial form "--header=-" disables header lines and header
columns,
and is equivalent to "--header=0,0".
When 4mL24m is nonzero, the first 4mL24m lines at the
top of the screen
are replaced with the 4mL24m lines of the file beginning at
line 4mN24m,
regardless of what part of the file is being viewed. When
head
er lines are displayed, any file contents before the header
line
cannot be viewed. When 4mC24m is nonzero, the first
4mC24m characters
displayed at the beginning of each line are replaced with
the
first 4mC24m characters of the line, even if the rest of
the line is
scrolled horizontally.
While the --header option is active, lines longer than
the
screen width are truncated, and the -S option is ignored.
--incsearch
Subsequent search commands will be "incremental"; that is,
1mless0m
will advance to the next line containing the search pattern
as
each character of the pattern is typed in.
--intr=4mc0m
Use the character 4mc24m instead of ^X to interrupt a
read when the
"Waiting for data" message is displayed. 4mc24m must be
an ASCII
character; that is, one with a value between 1 and 127
inclu
sive. A caret followed by a single character can be used
to
specify a control character.
--linenumwidth=4mn0m
Sets the minimum width of the line number field when the -N
op
tion is in effect to 4mn24m characters. The default is 7.
--matchshift=4mn0m
When -S is in effect, if a search match is not visible
because
it is shifted to the left or right of the currently
visible
screen, the text will horizontally shift to ensure that
the
search match is visible. This option selects the column
in
which the first character of the search match will be placed
af
ter the shift. In other words, there will be 4mn24m
characters visi
ble to the left of the search match.
Alternately, the number may be specified as a fraction of
the
width of the screen, starting with a decimal point: .5 is
half
of the screen width, .3 is three tenths of the screen width,
and
so on. If the number is specified as a fraction, the
actual
number of scroll positions is recalculated if the terminal
win
dow is resized.
--modelines=4mn0m
Before displaying a file, 1mless 22mwill read the first
4mn24m lines to
try to find a vimcompatible 4mmodeline24m. If 4mn24m
is zero, 1mless 22mdoes
not try to find modelines. By using a modeline, the file
itself
can specify the tab stops that should be used when viewing
it.
A modeline contains, anywhere in the line, a program name
("vi",
"vim", "ex", or "less"), followed by a colon, possibly
followed
by the word "set", and finally followed by zero or more
option
settings. If the word "set" is used, option settings are
sepa
rated by spaces, and end at the first colon. If the word
"set"
is not used, option settings may be separated by either
spaces
or colons. The word "set" is required if the program name
is
"less" but optional if any of the other three names are
used.
If any option setting is of the form "tabstop=4mn24m" or
"ts=4mn24m", then
tab stops are automatically set as if --tabs=4mn24m had
been given.
See the --tabs description for acceptable values of 4mn24m.
--mouse
Enables mouse input: scrolling the mouse wheel down moves
for
ward in the file, scrolling the mouse wheel up moves
backwards
in the file, leftclick sets the "#" mark to the line where
the
mouse is clicked, and rightclick (or any other) returns
to the
"#" mark position. Holding down the left button and
dragging
also moves in the file. If a leftclick is performed
with the
mouse cursor on an OSC 8 hyperlink, the hyperlink is selected
as
if by the ^O^N command. If a leftclick is performed with
the
mouse cursor on an OSC 8 hyperlink which is already
selected,
the hyperlink is opened as if by the ^O^O command. The
number
of lines to scroll when the wheel is moved can be set by
the
--wheellines option. Mouse input works only on terminals
which
support X11 mouse reporting, and on the Windows version of
1mless22m.
--MOUSE
Like --mouse, except the direction scrolled on mouse wheel
move
ment is reversed.
--noeditwarn
Dont print a warning message when using the v command on a
file
which was opened using a LESSOPEN preprocessor (see the
INPUT
PREPROCESSOR section below).
--nokeypad
Disables sending the keypad initialization and
deinitialization
strings to the terminal. This is sometimes useful if the
keypad
strings make the numeric keypad behave in an undesirable
manner.
--nohistdups
This option changes the behavior so that if a search string
or
file name is typed in, and the same string is already in
the
history list, the existing copy is removed from the history
list
before the new one is added. Thus, a given string will
appear
only once in the history list. Normally, a string may
appear
multiple times.
--nonumberheaders
Header lines (defined via the --header option) are not
assigned
line numbers. Line number 1 is assigned to the first line
after
any header lines.
--nopaste
If the terminal supports xtermcompatible "bracketed
paste", any
text pasted into 1mless 22mis ignored, except that one
line of text
may be pasted into the command line at the bottom of the
screen
(search strings, file names, etc). That is, the first
newline
of text pasted into the command line and any text that
follows
it is ignored.
--nosearchheaderlines
Searches do not include header lines, but still include
header
columns.
--nosearchheadercolumns
Searches do not include header columns, but still include
header
lines.
--nosearchheaders
Searches do not include header lines or header columns.
--novbell
Disables the terminals visual bell.
--procbackspace
If set, backspaces are handled as if neither the -u option
nor
the -U option were set. That is, a backspace adjacent to an
un
derscore causes text to be displayed in underline mode,
and a
backspace between identical characters cause text to be
dis
played in boldface mode. This option overrides the -u and
-U
options, so that display of backspaces can be controlled
sepa
rate from tabs and carriage returns. If not set, backspace
dis
play is controlled by the -u and -U options.
--PROCBACKSPACE
If set, backspaces are handled as if the -U option were
set;
that is backspaces are treated as control characters.
--procreturn
If set, carriage returns are handled as if neither the -u
option
nor the -U option were set. That is, a carriage return
immedi
ately before a newline is deleted. This option overrides the
-u
and -U options, so that display of carriage returns can be
con
trolled separate from that of backspaces and tabs. If not
set,
carriage return display is controlled by the -u and -U
options.
--PROCRETURN
If set, carriage returns are handled as if the -U option
were
set; that is carriage returns are treated as control
characters.
--proctab
If set, tabs are handled as if the -U option were not set.
That
is, tabs are expanded to spaces. This option overrides the
-U
option, so that display of tabs can be controlled separate
from
that of backspaces and carriage returns. If not set, tab
dis
play is controlled by the -U option.
--PROCTAB
If set, tabs are handled as if the -U option were set; that
is
tabs are treated as control characters.
--redrawonquit
When quitting, after sending the terminal
deinitialization
string, redraws the entire last screen. On terminals whose
ter
minal deinitialization string causes the terminal to switch
from
an alternate screen, this makes the last screenful of the
cur
rent file remain visible after 1mless 22mhas quit.
--rscroll=4mc0m
This option changes the character used to mark truncated
lines.
It may begin with a twocharacter attribute indicator like
LESS
BINFMT does. If there is no attribute indicator, standout
is
used. If set to "-", truncated lines are not marked.
--savemarks
Save marks in the history file, so marks are retained
across
different invocations of 1mless22m.
--searchoptions=4m...0m
Sets default search modifiers. The value is a string of one
or
more of the characters E, F, K, N, R or W. Setting any of
these
has the same effect as typing that control character at the
be
ginning of every search pattern. For example, setting --
search
options=W is the same as typing ^W at the beginning of
every
pattern. The value may also contain a digit between 1 and
5,
which has the same effect as typing ^S followed by that digit
at
the beginning of every search pattern. The value ""
disables
all default search modifiers.
--showpreprocerrors
If a preprocessor produces data, then exits with a nonzero
exit
code, 1mless 22mwill display a warning.
--statuscolwidth=4mn0m
Sets the width of the status column when the -J option is in
ef
fect. The default is 2 characters.
--statusline
If a line is marked, the entire line (rather than just the
sta
tus column) is highlighted. Also lines highlighted due to
the
-w option will have the entire line highlighted. If --
usecolor
is set, the line is colored rather than highlighted.
--usebackslash
This option changes the interpretations of options which
follow
this one. After the --usebackslash option, any backslash
in an
option string is removed and the following character is
taken
literally. This allows a dollar sign to be included in
option
strings.
--usecolor
Enables colored text in various places. The -D option can
be
used to change the colors. Colored text works only if the
ter
minal supports ANSI color escape sequences (as defined
in
https://www.ecmainternational.org/publicationsand
standards/standards/ecma48).
--wheellines=4mn0m
Set the number of lines to scroll when the mouse wheel
is
scrolled and the --mouse or --MOUSE option is in effect.
The
default is 1 line.
--wordwrap
When the -S option is not in use, wrap each line at a space
or
tab if possible, so that a word is not split between two
lines.
The default is to wrap at any character.
-- A command line argument of "--" marks the end of option
argu
ments. Any arguments following this are interpreted as
file
names. This can be useful when viewing a file whose name
begins
with a "-" or "+". Otherwise, option arguments and filename
ar
guments can be intermixed; that is, option arguments do not
need
to appear before filename arguments, unless the
environment
variable POSIXLY_CORRECT is set.
+ If a command line option begins with 1m+22m, the
remainder of that
option is taken to be an initial command to 1mless22m. For
example,
+G tells 1mless 22mto start at the end of the file
rather than the
beginning, and +/xyz tells it to start at the first
occurrence
of "xyz" in the file. As a special case, +<number> acts
like
+<number>g; that is, it starts the display at the specified
line
number (however, see the caveat under the "g" command
above).
If the option starts with ++, the initial command applies
to
every file being viewed, not just the first one. The +
command
described previously may also be used to set (or change) an
ini
tial command for every file. Also see the --cmd option.
1mLINE EDITING0m
When entering a command line at the bottom of the screen (for
example,
a filename for the :e command, or the pattern for a search
command),
certain keys can be used to manipulate the command line. Most
commands
have an alternate form in [ brackets ] which can be used if a key
does
not exist on a particular keyboard. (Note that the forms
beginning
with ESC do not work on some MSDOS and Windows systems because
ESC is
the line erase character.) Any of these special keys may be
entered
literally by preceding it with the "literal" character, either ^V
or
^A. A backslash itself may also be entered literally by entering
two
backslashes.
LEFTARROW [ ESCh ]
Move the cursor one space to the left.
RIGHTARROW [ ESCl ]
Move the cursor one space to the right.
^LEFTARROW [ ESCb or ESCLEFTARROW ]
(That is, CONTROL and LEFTARROW simultaneously.) Move the
cur
sor one word to the left.
^RIGHTARROW [ ESCw or ESCRIGHTARROW ]
(That is, CONTROL and RIGHTARROW simultaneously.) Move the
cur
sor one word to the right.
HOME [ ESC0 ]
Move the cursor to the beginning of the line.
END [ ESC$ ]
Move the cursor to the end of the line.
BACKSPACE
Delete the character to the left of the cursor, or cancel
the
command if the command line is empty.
DELETE or [ ESCx ]
Delete the character under the cursor.
^BACKSPACE [ ESCBACKSPACE ]
(That is, CONTROL and BACKSPACE simultaneously.) Delete
the
word to the left of the cursor.
^DELETE [ ESCX or ESCDELETE ]
(That is, CONTROL and DELETE simultaneously.) Delete the
word
under the cursor.
UPARROW [ ESCk ]
Retrieve the previous command line. If you first enter
some
text and then press UPARROW, it will retrieve the previous
com
mand which begins with that text.
DOWNARROW [ ESCj ]
Retrieve the next command line. If you first enter some
text
and then press DOWNARROW, it will retrieve the next
command
which begins with that text.
TAB Complete the partial filename to the left of the cursor. If
it
matches more than one filename, the first match is entered
into
the command line. Repeated TABs will cycle thru the
other
matching filenames. If the completed filename is a
directory, a
"/" is appended to the filename. (On MSDOS and Windows
sys
tems, a "
TOR can be used to specify a different character to append to
a
directory name.
BACKTAB [ ESCTAB ]
Like, TAB, but cycles in the reverse direction thru the
matching
filenames.
^L Complete the partial filename to the left of the cursor. If
it
matches more than one filename, all matches are entered into
the
command line (if they fit).
^U (Unix and OS/2) or ESC (MSDOS and Windows)
Delete the entire command line, or cancel the command if
the
cursor is at the beginning of the command line. If you
have
changed your linekill character in Unix to something other
than
^U, that character is used instead of ^U.
^G Delete the entire command line and return to the main prompt.
1mKEY BINDINGS0m
You may define your own 1mless 22mcommands by creating a
lesskey source
file. This file specifies a set of command keys and an action
associ
ated with each key. You may also change the lineediting keys
(see
LINE EDITING), and set environment variables used by
1mless22m. See the
1mlesskey22m(1) manual page for details about the file format.
If the environment variable LESSKEYIN is set, 1mless 22muses
that as the
name of the lesskey source file. Otherwise, 1mless 22mlooks in
a standard
place for the lesskey source file: On Unix systems, 1mless
22mlooks for a
lesskey file called "$XDG_CONFIG_HOME/lesskey" or
"$HOME/.con
fig/lesskey" or "$HOME/.lesskey". On MSDOS and Windows systems,
1mless0m
looks for a lesskey file called "$HOME/_lesskey", and if it is
not
found there, then looks for a lesskey file called "_lesskey" in any
di
rectory specified in the PATH environment variable. On OS/2
systems,
1mless 22mlooks for a lesskey file called "$HOME/lesskey.ini",
and if it is
not found, then looks for a lesskey file called "lesskey.ini" in
any
directory specified in the INIT environment variable, and if it
not
found there, then looks for a lesskey file called "lesskey.ini" in
any
directory specified in the PATH environment variable.
A systemwide lesskey source file may also be set up to
provide key
bindings. If a key is defined in both a local lesskey file and in
the
systemwide file, key bindings in the local file take precedence
over
those in the systemwide file. If the environment
variable
LESSKEYIN_SYSTEM is set, 1mless 22muses that as the name of the
systemwide
lesskey file. Otherwise, 1mless 22mlooks in a standard place for
the sys
temwide lesskey file: On Unix systems, the systemwide lesskey
file is
/usr/local/etc/syslesskey. (However, if 1mless 22mwas built with
a differ
ent sysconf directory than /usr/local/etc, that directory is where
the
sysless file is found.) On MSDOS and Windows systems, the
systemwide
lesskey file is c:_syslesskey. On OS/2 systems, the
systemwide
lesskey file is c:slesskey.ini.
Older versions of 1mless 22m(before v582) used lesskey files with
a binary
format, produced by the 1mlesskey 22mprogram. It is no longer
necessary to
use the 1mlesskey 22mprogram.
1mINPUT PREPROCESSOR0m
You may define an "input preprocessor" for 1mless22m. Before
1mless 22mopens a
file, it first gives the input preprocessor a chance to modify the
way
the contents of the file are displayed. An input preprocessor is
sim
ply an executable program (or shell script), which writes the
contents
of the file to a different file, called the replacement file. The
con
tents of the replacement file are then displayed in place of the
con
tents of the original file. However, it will appear to the user as
if
the original file is opened; that is, 1mless 22mwill display the
original
filename as the name of the current file.
An input preprocessor receives one command line argument, the
original
filename, as entered by the user. It should create the
replacement
file, and when finished, print the name of the replacement file to
its
standard output. If the input preprocessor does not output a
replace
ment filename, 1mless 22muses the original file, as normal. The
input pre
processor is not called when viewing standard input. To set up an
in
put preprocessor, set the LESSOPEN environment variable to a
command
line which will invoke your input preprocessor. This command
line
should include one occurrence of the string "%s", which will be
re
placed by the filename when the input preprocessor command is
invoked.
When 1mless 22mcloses a file opened in such a way, it will call
another pro
gram, called the input postprocessor, which may perform any
desired
cleanup action (such as deleting the replacement file
created by
LESSOPEN). This program receives two command line arguments, the
orig
inal filename as entered by the user, and the name of the
replacement
file. To set up an input postprocessor, set the LESSCLOSE
environment
variable to a command line which will invoke your input
postprocessor.
It may include two occurrences of the string "%s"; the first is
re
placed with the original name of the file and the second with the
name
of the replacement file, which was output by LESSOPEN.
For example, on many Unix systems, these two scripts will allow you
to
keep files in compressed format, but still let 1mless 22mview them
directly:
lessopen.sh:
#! /bin/sh
case "$1" in
*.Z) TEMPFILE=$(mktemp)
uncompress -c $1 >$TEMPFILE 2>/dev/null
if [ -s $TEMPFILE ]; then
echo $TEMPFILE
else
rm -f $TEMPFILE
fi
;;
esac
lessclose.sh:
#! /bin/sh
rm $2
To use these scripts, put them both where they can be executed and
set
LESSOPEN="lessopen.sh %s", and LESSCLOSE="lessclose.sh %s %s".
More
complex LESSOPEN and LESSCLOSE scripts may be written to accept
other
types of compressed files, and so on.
It is also possible to set up an input preprocessor to pipe the
file
data directly to 1mless22m, rather than putting the data into a
replacement
file. This avoids the need to decompress the entire file before
start
ing to view it. An input preprocessor that works this way is called
an
input pipe. An input pipe, instead of writing the name of a
replace
ment file on its standard output, writes the entire contents of the
re
placement file on its standard output. If the input pipe does
not
write any characters on its standard output, then there is no
replace
ment file and 1mless 22muses the original file, as normal. To use
an input
pipe, make the first character in the LESSOPEN environment
variable a
vertical bar (|) to signify that the input preprocessor is an
input
pipe. As with nonpipe input preprocessors, the command string
must
contain one occurrence of %s, which is replaced with the filename
of
the input file.
For example, on many Unix systems, this script will work like the
pre
vious example scripts:
lesspipe.sh:
#! /bin/sh
case "$1" in
*.Z) uncompress -c $1 2>/dev/null
;;
*) exit 1
;;
esac
exit $?
To use this script, put it where it can be executed and
set
LESSOPEN="|lesspipe.sh %s".
Note that a preprocessor cannot output an empty file, since that is
in
terpreted as meaning there is no replacement, and the original file
is
used. To avoid this, if LESSOPEN starts with two vertical bars,
the
exit status of the script determines the behavior when the output
is
empty. If the output is empty and the exit status is zero, the
empty
output is considered to be replacement text. If the output is
empty
and the exit status is nonzero, the original file is used. For
compat
ibility with previous versions of 1mless22m, if LESSOPEN starts
with only
one vertical bar, the exit status of the preprocessor is ignored.
When an input pipe is used, a LESSCLOSE postprocessor can be used,
but
it is usually not necessary since there is no replacement file to
clean
up. In this case, the replacement file name passed to the
LESSCLOSE
postprocessor is "-".
For compatibility with previous versions of 1mless22m, the input
preproces
sor or pipe is not used if 1mless 22mis viewing standard input.
However, if
the first character of LESSOPEN is a dash (-), the input
preprocessor
is used on standard input as well as other files. In this case,
the
dash is not considered to be part of the preprocessor command.
If
standard input is being viewed, the input preprocessor is passed a
file
name consisting of a single dash. Similarly, if the first two
charac
ters of LESSOPEN are vertical bar and dash (|-) or two vertical
bars
and a dash (||-), the input pipe is used on standard input as well
as
other files. Again, in this case the dash is not considered to be
part
of the input pipe command.
1mNATIONAL CHARACTER SETS0m
There are five types of characters in the input file:
normal characters
can be displayed directly to the screen.
control characters
should not be displayed directly, but are expected to be
found
in ordinary text files (such as backspace and tab).
binary characters
should not be displayed directly and are not expected to
be
found in text files.
composing characters
are not displayed separately, but modify the display of the
pre
ceding character. (Only when LESSCHARSET is "utf8".)
deleted characters
are simply deleted from the input and not displayed. (Only
when
LESSCHARSET is "utf8".)
A "character set" is simply a description of which characters are to
be
considered normal, control, and binary. The LESSCHARSET
environment
variable may be used to select a character set. Possible values
for
LESSCHARSET are:
ascii BS, TAB, NL, CR, and formfeed are control characters, all
chars
with values between 32 and 126 are normal, and all others
are
binary.
iso8859
Selects an ISO 8859 character set. This is the same as
ASCII,
except characters between 160 and 255 are treated as
normal
characters.
latin1 Same as iso8859.
latin9 Same as iso8859.
dos Selects a character set appropriate for MSDOS.
ebcdic Selects an EBCDIC character set.
IBM1047
Selects an EBCDIC character set used by OS/390 Unix
Services.
This is the EBCDIC analogue of latin1. You get similar
results
by setting either LESSCHARSET=IBM1047 or LC_CTYPE=en_US in
your
environment.
koi8r Selects a Russian character set.
next Selects a character set appropriate for NeXT computers.
utf8 Selects the UTF8 encoding of the ISO 10646
character set.
UTF8 is special in that it supports multibyte
characters in
the input file. It is the only character set that supports
mul
tibyte characters.
windows
Selects a character set appropriate for Microsoft Windows
(cp
1252).
In rare cases, it may be desired to tailor 1mless 22mto use a
character set
other than the ones definable by LESSCHARSET. In this case, the
envi
ronment variable LESSCHARDEF can be used to define a character set.
It
should be set to a string where each character in the string
represents
one character in the character set. The character "." is used
for a
normal character, "c" for control, and "b" for binary. A decimal
num
ber may be used for repetition. For example, "bccc4b." would
mean
character 0 is binary, 1, 2 and 3 are control, 4, 5, 6 and 7 are
bina
ry, and 8 is normal. All characters after the last are taken to be
the
same as the last, so characters 9 through 255 would be normal.
(This
is an example, and does not necessarily represent any real
character
set.)
This table shows the value of LESSCHARDEF which is equivalent to
each
of the possible values for LESSCHARSET:
ascii 8bcccbcc18b95.b
dos 8bcccbcc12bc5b95.b.
ebcdic 5bc6bcc7bcc41b.9b7.9b5.b..8b6.10b6.b9.7b
9.8b8.17b3.3b9.7b9.8b8.6b10.b.b.b.
IBM1047 4cbcbc3b9cbccbccbb4c6bcc5b3cbbc4bc4bccbc
191.b
iso8859 8bcccbcc18b95.33b.
koi8r 8bcccbcc18b95.b128.
latin1 8bcccbcc18b95.33b.
next 8bcccbcc18b95.bb125.bb
If neither LESSCHARSET nor LESSCHARDEF is set, but any of the
strings
"UTF8", "UTF8", "utf8" or "utf8" is found in the LC_ALL,
LC_CTYPE or
LANG environment variables, then the default character set is
utf8.
If that string is not found, but your system supports the
1msetlocale 22min
terface, 1mless 22mwill use setlocale to determine the character
set. set
locale is controlled by setting the LANG or LC_CTYPE environment
vari
ables.
Finally, if the 4msetlocale24m interface is also not available,
the default
character set is utf8.
Control and binary characters are displayed in standout
(reverse
video). Each such character is displayed in caret notation if
possible
(e.g. ^A for controlA). Caret notation is used only if inverting
the
0100 bit results in a normal printable character. Otherwise, the
char
acter is displayed as a hex number in angle brackets. This format
can
be changed by setting the LESSBINFMT environment variable.
LESSBINFMT
may begin with a "*" and one character to select the display
attribute:
"*k" is blinking, "*d" is bold, "*u" is underlined, "*s" is
standout,
and "*n" is normal. If LESSBINFMT does not begin with a "*",
normal
attribute is assumed. The remainder of LESSBINFMT is a string
which
may include one printfstyle escape sequence (a % followed by x,
X, o,
d, etc.). For example, if LESSBINFMT is "*u[%x]", binary
characters
are displayed in underlined hexadecimal surrounded by brackets.
The
default if no LESSBINFMT is specified is "*s<%02X>". Warning: the
re
sult of expanding the character via LESSBINFMT must be less than
31
characters.
When the character set is utf8, the LESSUTFBINFMT environment
variable
acts similarly to LESSBINFMT but it applies to Unicode code points
that
were successfully decoded but are unsuitable for display (e.g.,
unas
signed code points). Its default value is "<U+%04lX>". Note
that
LESSUTFBINFMT and LESSBINFMT share their display attribute
setting
("*x") so specifying one will affect both; LESSUTFBINFMT is read
after
LESSBINFMT so its setting, if any, will have priority.
Problematic
octets in a UTF8 file (octets of a truncated sequence, octets
of a
complete but nonshortest form sequence, invalid octets, and
stray
trailing octets) are displayed individually using LESSBINFMT so as
to
facilitate diagnostic of how the UTF8 file is illformed.
When the character set is utf8, in rare cases it may be
desirable to
override the Unicode definition of the type of certain characters.
For
example, characters in a Private Use Area are normally treated as
bina
ry characters, but if you are using a custom font with printable
char
acters in that range, it may be desirable to tell 1mless 22mto
treat such
characters as printable. This can be done by setting the
LESSUTFCHARD
EF environment variable to a commaseparated list of
4mcharacter24m 4mtype24m de
finitions. Each character type definition consists of either one
hexa
decimal codepoint or a pair of codepoints separated by a dash,
followed
by a colon and a type character. Each hexadecimal codepoint may
op
tionally be preceded by a "U" or "U+". If a pair of codepoints is
giv
en, the type is set for all characters inclusively between the two
val
ues. If there are multiple commaseparated codepoint values, they
must
be in ascending numerical order. The type character may be one of:
p A normal printable character.
w A wide (2space) printable character.
b A binary (nonprintable) character.
c A composing (zero width) character.
d A deleted character (deleted from the input and not
dis
played).
For example, setting LESSUTFCHARDEF to
E000F8FF:p,F0000FFFFD:p,10000010FFFD:p
would make all Private Use Area characters be treated as printable.
By default, emoji modifiers, components and variation selectors
are
deleted because many terminals do not display them correctly. If
you
use a terminal which does display some or all of them correctly,
you
can cause to be displayed by setting LESSUTFCHARDEF to treat them
as
composing characters. For example, this sets them all to
composing
characters:
FE00FE0F:c,1F3FB1F3FF:c,1F9B01F9B3:c,E0100E01EF:c
1mPROMPTS0m
The -P option allows you to tailor the prompt to your preference.
The
string given to the -P option replaces the specified prompt
string.
Certain characters in the string are interpreted specially. The
prompt
mechanism is rather complicated to provide flexibility, but the
ordi
nary user need not understand the details of constructing
personalized
prompt strings.
A percent sign followed by a single character is expanded according
to
what the following character is. (References to the input file
size
below refer to the preprocessed size, if an input preprocessor is
being
used.)
%b4mX24m Replaced by the byte offset into the current input
file. The b
is followed by a single character (shown as 4mX24m above)
which spec
ifies the line whose byte offset is to be used. If the
charac
ter is a "t", the byte offset of the top line in the display
is
used, an "m" means use the middle line, a "b" means use the
bot
tom line, a "B" means use the line just after the bottom
line,
and a "j" means use the "target" line, as specified by the
-j
option.
%B Replaced by the size of the current input file.
%c Replaced by the column number of the text appearing in the
first
column of the screen.
%d4mX24m Replaced by the page number of a line in the input
file. The
line to be used is determined by the 4mX24m, as with the %b
option.
%D Replaced by the number of pages in the input file, or
equiva
lently, the page number of the last line in the input file.
%E Replaced by the name of the editor (from the VISUAL
environment
variable, or the EDITOR environment variable if VISUAL is
not
defined). See the discussion of the LESSEDIT feature below.
%f Replaced by the name of the current input file.
%F Replaced by the last component of the name of the current
input
file.
%g Replaced by the shellescaped name of the current input
file.
This is useful when the expanded string will be used in a
shell
command, such as in LESSEDIT.
%i Replaced by the index of the current file in the list of
input
files.
%l4mX24m Replaced by the line number of a line in the input
file. The
line to be used is determined by the 4mX24m, as with the %b
option.
%L Replaced by the line number of the last line in the input
file.
%m Replaced by the total number of input files.
%o Replaced by the URI of the currently selected OSC 8
hyperlink,
or a question mark if no hyperlink is selected. This is used
by
OSC 8 handlers as explained in the ^O^O command description.
%p4mX24m Replaced by the percent into the current input file,
based on
byte offsets. The line used is determined by the 4mX24m
as with the
%b option.
%P4mX24m Replaced by the percent into the current input file,
based on
line numbers. The line used is determined by the 4mX24m
as with the
%b option.
%s Same as %B.
%t Causes any trailing spaces to be removed. Usually used at
the
end of the string, but may appear anywhere.
%T Normally expands to the word "file". However if viewing
files
via a tags list using the -t option, it expands to the
word
"tag".
%x Replaced by the name of the next input file in the list.
If any item is unknown (for example, the file size if input is a
pipe),
a question mark is printed instead.
The format of the prompt string can be changed depending on
certain
conditions. A question mark followed by a single character acts
like
an "IF": depending on the following character, a condition is
evaluat
ed. If the condition is true, any characters following the
question
mark and condition character, up to a period, are included in
the
prompt. If the condition is false, such characters are not
included.
A colon appearing between the question mark and the period can be
used
to establish an "ELSE": any characters between the colon and the
period
are included in the string if and only if the IF condition is
false.
Condition characters (which follow a question mark) may be:
?a True if any characters have been included in the prompt so
far.
?b4mX24m True if the byte offset of the specified line is
known.
?B True if the size of current input file is known.
?c True if the text is horizontally shifted (%c is not zero).
?d4mX24m True if the page number of the specified line is
known.
?e True if at endoffile.
?f True if there is an input filename (that is, if input is
not a
pipe).
?l4mX24m True if the line number of the specified line is
known.
?L True if the line number of the last line in the file is
known.
?m True if there is more than one input file.
?n True if this is the first prompt in a new input file.
?p4mX24m True if the percent into the current input file, based
on byte
offsets, of the specified line is known.
?P4mX24m True if the percent into the current input file,
based on line
numbers, of the specified line is known.
?s Same as "?B".
?x True if there is a next input file (that is, if the current
in
put file is not the last one).
Any characters other than the special ones (question mark, colon,
peri
od, percent, and backslash) become literally part of the prompt.
Any
of the special characters may be included in the prompt literally
by
preceding it with a backslash.
Some examples:
?f%f:Standard input.
This prompt prints the filename, if known; otherwise the string
"Stan
dard input".
?f%f .?ltLine %lt:?pt%pt:?btByte %bt:...
This prompt would print the filename, if known. The filename is
fol
lowed by the line number, if known, otherwise the percent if
known,
otherwise the byte offset if known. Otherwise, a dash is printed.
No
tice how each question mark has a matching period, and how the %
after
the %pt is included literally by escaping it with a backslash.
%x..%t
?n?f%f .?m(%T %i of %m) ..?e(END) ?x Next
This prints the filename if this is the first prompt in a file,
fol
lowed by the "file N of N" message if there is more than one
input
file. Then, if we are at endoffile, the string "(END)" is
printed
followed by the name of the next file, if there is one. Finally,
any
trailing spaces are truncated. This is the default prompt. For
refer
ence, here are the defaults for the other two prompts (-m and -M
re
spectively). Each is broken into two lines here for readability
only.
%x.:
?n?f%?pB%pB:byte %bB?s/%s...%tND) ?x Next
?f%f .?n?m(%T %i of %m) ..?ltlines %l%x.:?pB%pB..%t
byte %bB?s/%s. .?e(END) ?x Next
And here is the default message produced by the = command:
?f%f .?m(%T %i of %m) .?ltlines %lt%lb?L/%L. .
byte %bB?s/%s. ?e(END) :?pB%pB..%t
The prompt expansion features are also used for another purpose: if
an
environment variable LESSEDIT is defined, it is used as the command
to
be executed when the v command is invoked. The LESSEDIT string is
ex
panded in the same way as the prompt strings. The default value
for
LESSEDIT is:
%E ?lm+%lm. %g
Note that this expands to the editor name, followed by a + and the
line
number, followed by the shellescaped file name. If your editor
does
not accept the "+linenumber" syntax, or has other differences in
invo
cation syntax, the LESSEDIT variable can be changed to modify this
de
fault.
1mSECURITY0m
When the environment variable LESSSECURE is set to 1, 1mless
22mruns in a
"secure" mode. In this mode, these features are disabled:
edit the edit command (v)
examine the examine command (:e)
glob metacharacters such as * in filenames,
and filename completion (TAB, ^L)
history history file
lesskey use of lesskey files (k and --lesskeysrc)
lessopen input preprocessor (LESSOPEN environment variable)
logfile log files (s and -o)
osc8 opening OSC 8 links (^O^O)
pipe the pipe command (|)
shell the shell and pshell commands (! and #)
stop stopping 1mless 22mvia a SIGTSTP signal
tags use of tags files (t)
The LESSSECURE_ALLOW environment variable can be set to a
commasepa
rated list of names of features which are selectively enabled
when
LESSSECURE is set. Each feature name is the first word in each line
in
the above list. A feature name may be abbreviated as long as the
ab
breviation is unambiguous. For example, if LESSSECURE=1
and
LESSSECURE_ALLOW=hist,edit were set, all of the above features would
be
disabled except for history files and the edit command.
Less can also be compiled to be permanently in "secure" mode. In
that
case, the LESSSECURE and LESSSECURE_ALLOW variables are ignored.
1mCOMPATIBILITY WITH MORE0m
If the environment variable LESS_IS_MORE is set to 1, or if the
program
is invoked via a file link named "more" and the environment
variable
LESS_IS_MORE is not set to 0, 1mless 22mbehaves (mostly) in
conformance with
the POSIX 1mmore22m(1) command specification. In this mode,
less behaves
differently in these ways:
The -e option works differently. If the -e option is not set,
1mless 22mbe
haves as if the -e option were set. If the -e option is set,
1mless 22mbe
haves as if the -E option were set.
The -m option works differently. If the -m option is not set,
the
medium prompt is used, and it is prefixed with the string "--
More--".
If the -m option is set, the short prompt is used.
The -n option acts like the -z option. The normal behavior of the
-n
option is unavailable in this mode.
The parameter to the -p option is taken to be a 1mless
22mcommand rather
than a search pattern.
The LESS environment variable is ignored, and the MORE
environment
variable is used in its place.
1mENVIRONMENT VARIABLES0m
Environment variables may be specified either in the system
environment
as usual, or in a 1mlesskey22m(1) file. If environment
variables are de
fined in more than one place, variables defined in a local lesskey
file
take precedence over variables defined in the system environment,
which
take precedence over variables defined in the systemwide lesskey
file.
COLUMNS
Sets the number of columns on the screen. Takes precedence
over
the number of columns specified by the TERM variable. (But
if
you have a windowing system which supports TIOCGWINSZ
or
WIOCGETD, the window systems idea of the screen size
takes
precedence over the LINES and COLUMNS environment variables.)
EDITOR The name of the editor (used for the v command).
HOME Name of the users home directory (used to find a lesskey
file
on Unix and OS/2 systems).
HOMEDRIVE, HOMEPATH
Concatenation of the HOMEDRIVE and HOMEPATH environment
vari
ables is the name of the users home directory if the HOME
vari
able is not set (only in the Windows version).
INIT Name of the users init directory (used to find a lesskey
file
on OS/2 systems).
LANG Language for determining the character set.
LC_CTYPE
Language for determining the character set.
LESS Options which are passed to 1mless 22mautomatically.
LESSANSIENDCHARS
Characters which may end an ANSI color escape sequence
(default
"m").
LESSANSIMIDCHARS
Characters which may appear between the ESC character and
the
end character in an ANSI color escape sequence
(default
"0123456789:;[?!"'#%()*+ ").
LESSANSIOSCALLOW
A commaseparated list of OSC types which are output
directly to
the terminal when -R is in effect (default "8"; that is,
only
OSC 8 sequences are output directly).
LESSANSIOSCCHARS
Characters which may follow an ESC character to mark the
start
of an "OS Command" sequence. All characters that follow
this
character up to a String Terminator (ESCbackslash or BEL)
are
considered to be part of the OSC sequence (default "]").
If a
character in LESSANSIOSCCHARS is followed by an asterisk,
se
quences that begin with that character in the file contents
are
passed through to the terminal; otherwise only sequences
that
appear in a prompt string are passed through.
LESSBINFMT
Format for displaying nonprintable, noncontrol
characters.
LESSCHARDEF
Defines a character set.
LESSCHARSET
Selects a predefined character set.
LESSCLOSE
Command line to invoke the (optional) inputpostprocessor.
LESSECHO
Name of the lessecho program (default "lessecho"). The
lessecho
program is needed to expand metacharacters, such as * and ?,
in
filenames on Unix systems.
LESSEDIT
Editor prototype string (used for the v command). See
discus
sion under PROMPTS.
LESSGLOBALTAGS
Name of the command used by the -t option to find global
tags.
Normally should be set to "global" if your system has the
1mglob0m
1mal22m(1) command. If not set, global tags are not used.
LESSHISTFILE
Name of the history file used to remember search commands
and
shell commands between invocations of 1mless22m. If set
to "-" or
"/dev/null", a history file is not used. The default depends
on
the operating system, but is usually:
Linux and Unix
"$XDG_STATE_HOME/lesshst" or
"$HOME/.local/state/lesshst"
or "$XDG_DATA_HOME/lesshst" or "$HOME/.lesshst".
Windows and MSDOS
"$HOME/_lesshst".
OS/2 "$HOME/lesshst.ini" or "$INIT/lesshst.ini".
LESSHISTSIZE
The maximum number of commands to save in the history file.
The
default is 100.
LESSKEYIN
Name of the default 4mlesskey24m 4msource24m file.
LESSKEY
Name of the default 4mlesskey24m 4mbinary24m
file. (Not used if
"$LESSKEYIN" exists.)
LESSKEY_CONTENT
The value is parsed as if it were the parameter of a --
lesskey
content option.
LESSKEYIN_SYSTEM
Name of the default systemwide 4mlesskey24m
4msource24m file.
LESSKEY_SYSTEM
Name of the default systemwide 4mlesskey24m
4mbinary24m file. (Not used
if "$LESSKEYIN_SYSTEM" exists.)
LESSMETACHARS
List of characters which are considered "metacharacters" by
the
shell.
LESSMETAESCAPE
Prefix which less will add before each metacharacter in a
com
mand sent to the shell (default "
LESSOPEN
Command line to invoke the (optional) inputpreprocessor.
LESSSECURE
Runs less in "secure" mode. See discussion under SECURITY.
LESSSECURE_ALLOW
Enables individual features which are normally disabled
by
LESSSECURE. See discussion under SECURITY.
LESSSEPARATOR
String to be appended to a directory name in filename
completion
(default "
LESSUTFBINFMT
Format for displaying nonprintable Unicode code points.
LESSUTFCHARDEF
Overrides the type of specified Unicode characters.
LESS_COLUMNS
Sets the number of columns on the screen. Unlike COLUMNS,
takes
precedence over the systems idea of the screen size, so
it can
be used to make 1mless 22muse less than the full screen
width. If
set to a negative number, sets the number of columns used
to
this much less than the actual screen width.
LESS_LINES
Sets the number of lines on the screen. Unlike LINES,
takes
precedence over the systems idea of the screen size, so
it can
be used to make 1mless 22muse less than the full screen
height. If
set to a negative number, sets the number of lines used to
this
much less than the actual screen height. When set,
1mless 22mre
paints the entire screen on every movement command, so
scrolling
may be slower.
LESS_DATA_DELAY
Duration (in milliseconds) after starting to read data from
the
input, after which the "Waiting for data" message will be
dis
played. The default is 4000 (4 seconds).
LESS_IS_MORE
Emulate the 1mmore22m(1) command.
LESS_OSC8_xxx
Where "xxx" is a URI scheme such as "http" or "file", sets
an
OSC 8 handler for opening OSC 8 links containing a URI with
that
scheme.
LESS_OSC8_ANY
Sets an OSC 8 handler for opening OSC 8 links for which there
is
no specific LESS_OSC8_xxx handler set for the "xxx" scheme.
LESS_SHELL_LINES
When the -F option is set, 1mless 22mexits automatically if
the num
ber of screen lines used to display the file is less than
or
equal to the screen height minus the value of
the
LESS_SHELL_LINES variable. Thus, if you use a shell
prompt
which occupies more than one screen line, this variable can
be
set to the number of lines used by your prompt, to ensure
that
the entire file can be seen when -F is used. If not
set,
LESS_SHELL_LINES is assumed to be 1.
LESS_SIGUSR1
If set to a string of one or more 1mless 22mcommand
characters, those
commands will be executed when 1mless 22mreceives a SIGUSR1
signal.
LESS_TERMCAP_xx
Where "xx" is any two characters, overrides the definition
of
the termcap "xx" capability for the terminal.
LESS_TERMCAP_BRACKETED_PASTE_START
Overrides the standard ANSI escape sequence to enable
bracketed
paste. This is used when the --nopaste option is in
effect.
LESS_TERMCAP_BRACKETED_PASTE_END
Overrides the standard ANSI escape sequence to disable
bracketed
paste.
LESS_TERMCAP_MOUSE_START
Overrides the standard ANSI escape sequence to enable mouse
re
porting. This is used when the --mouse option is in effect.
LESS_TERMCAP_MOUSE_END
Overrides the standard ANSI escape sequence to disable mouse
re
porting.
LESS_TERMCAP_SUSPEND
Defines an escape sequence to temporarily suspend screen
up
dates. This is sent to the terminal before clearing the
screen.
This can be used to avoid screen tearing when the screen is
re
drawn on certain terminals.
LESS_TERMCAP_RESUME
Defines an escape sequence to resume screen updates. This
is
sent to the terminal after displaying the prompt.
LESS_UNSUPPORT
A spaceseparated list of command line options. These
options
will be ignored (with no error message) if they appear on
the
command line or in the LESS environment variable. Options
list
ed in LESS_UNSUPPORT can still be changed by the - and --
com
mands. Each option in LESS_UNSUPPORT is a dash followed by
a
single character option letter, or two dashes followed by a
long
option name.
LINES Sets the number of lines on the screen. Takes precedence
over
the number of lines specified by the TERM variable. (But if
you
have a windowing system which supports TIOCGWINSZ or
WIOCGETD,
the window systems idea of the screen size takes
precedence
over the LINES and COLUMNS environment variables.)
MORE Options which are passed to 1mless 22mautomatically when
running in
1mmore22mcompatible mode.
PATH Users search path (used to find a lesskey file on
MSDOS, Win
dows, and OS/2 systems).
POSIXLY_CORRECT
If set to any value, all option arguments on the command
line
are expected to appear before any filename arguments. This
must
be set as an actual environment variable, not in a 1mlesskey
22mfile.
SHELL The shell used to execute the ! command, as well as to
expand
filenames.
TERM The type of terminal on which 1mless 22mis being run.
VISUAL The name of the editor (used for the v command).
XDG_CONFIG_HOME
Possible location of the 1mlesskey 22mfile; see the KEY
BINDINGS sec
tion.
XDG_DATA_HOME
Possible location of the history file; see the description
of
the LESSHISTFILE environment variable.
XDG_STATE_HOME
Possible location of the history file; see the description
of
the LESSHISTFILE environment variable.
1mSEE ALSO0m
1mlesskey22m(1), 1mlessecho22m(1)
1mCOPYRIGHT0m
Copyright (C) 19842025 Mark Nudelman
less is part of the GNU project and is free software. You can
redis
tribute it and/or modify it under the terms of either (1) the GNU
Gen
eral Public License as published by the Free Software Foundation;
or
(2) the Less License. See the file README in the less distribution
for
more details regarding redistribution. You should have received a
copy
of the GNU General Public License along with the source for less;
see
the file COPYING. If not, write to the Free Software Foundation,
59
Temple Place, Suite 330, Boston, MA 021111307, USA. You should
also
have received a copy of the Less License; see the file LICENSE.
less is distributed in the hope that it will be useful, but WITHOUT
ANY
WARRANTY; without even the implied warranty of MERCHANTABILITY or
FIT
NESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
for
more details.
1mAUTHOR0m
Mark Nudelman
Report bugs at https://github.com/gwsw/less/issues.
For more information, see the less homepage at
https://greenwoodsoftware.com/less.
Version 685: 04 Oct 2025
4mLESS24m(1)
