SAM(1) SAM(1)
1editor
NAME
sam - screen editor with structural regular expressions
SYNOPSIS
sam [ option ... ] [ files ]
sam -r machine
sam.save
B [ -nnnn ] file ...
DESCRIPTION
Sam is a multi-file editor. It modifies a local copy of an external
file. The copy is here called a file. The files are listed in a menu
available through mouse button 3 or the n command. Each file has an
associated name, usually the name of the external file from which it
was read, and a `modified' bit that indicates whether the editor's
file agrees with the external file. The external file is not read
into the editor's file until it first becomes the current file-that to
which editing commands apply-whereupon its menu entry is printed. The
options are
-d Do not download the terminal part of sam. Editing will be done
with the command language only, as in ed(1).
-r machine
Run the host part remotely on the specified machine, the terminal
part locally.
-s file
Start the host part from the indicated file on the remote host.
Only meaningful with the -r option.
-t path
Start the terminal part from the indicated file. Useful for
debugging.
The standard X11 -geom toolkit option can be used to select the
desired window geometry.
Regular expressions
Regular expressions are as in regexp(6) with the addition of \n to
represent newlines. A regular expression may never contain a literal
newline character. The elements of regular expressions are:
. Match any character except newline.
\n Match newline.
\x For any character except n match the character (here x).
[abc]
Match any character in the square brackets. \n may be mentioned.
[^abc]
Match any character not in the square brackets, but never a
newline. Both these forms accept a range of ASCII characters
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indicated by a dash, as in a-z.
^ Match the null string immediately after a newline.
$ Match the null string immediately before a newline.
Any other character except newline matches itself.
In the following, r1 and r2 are regular expressions.
(r1) Match what r1 matches.
r1|r2
Match what r1 or what r2 matches.
r1* Match zero or more adjacent matches of r1.
r1+ Match one or more adjacent matches of r1.
r1? Match zero or one matches of r1.
The operators *, + and ? are highest precedence, then catenation, then
| is lowest. The empty regular expression stands for the last
complete expression encountered. A regular expression in sam matches
the longest leftmost substring formally matched by the expression.
Searching in the reverse direction is equivalent to searching
backwards with the catenation operations reversed in the expression.
Addresses
An address identifies a substring in a file. In the following,
`character n' means the null string after the n-th character in the
file, with 1 the first character in the file. `Line n' means the n-th
match, starting at the beginning of the file, of the regular
expression .*\n?. (The peculiar properties of a last line without a
newline are temporarily undefined.) All files always have a current
substring, called dot, that is the default address.
Simple Addresses
#n The empty string after character n; #0 is the beginning of
the file.
n Line n.
/regexp/
?regexp? The substring that matches the regular expression, found by
looking toward the end (/) or beginning (?) of the file, and
if necessary continuing the search from the other end to the
starting point of the search. The matched substring may
straddle the starting point. When entering a pattern
containing a literal question mark for a backward search,
the question mark should be specified as a member of a
class.
0 The string before the first full line. This is not
necessarily the null string; see + and - below.
$ The null string at the end of the file.
. Dot.
' The mark in the file (see the k command below).
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"regexp" Preceding a simple address (default .), refers to the
address evaluated in the unique file whose menu line matches
the regular expression.
Compound Addresses
In the following, a1 and a2 are addresses.
a1+a2
The address a2 evaluated starting at the end of a1.
a1-a2
The address a2 evaluated looking in the reverse direction
starting at the beginning of a1.
a1,a2
The substring from the beginning of a1 to the end of a2. If a1
is missing, 0 is substituted. If a2 is missing, $ is
substituted.
a1;a2
Like a1,a2, but with a2 evaluated at the end of, and dot set to,
a1.
The operators + and - are high precedence, while , and ; are low
precedence.
In both + and - forms, if a2 is a line or character address with a
missing number, the number defaults to 1. If a1 is missing, . is
substituted. If both a1 and a2 are present and distinguishable, + may
be elided. a2 may be a regular expression; if it is delimited by ?'s,
the effect of the + or - is reversed.
It is an error for a compound address to represent a malformed
substring. Some useful idioms: a1+- (a1-+) selects the line
containing the end (beginning) of a1. 0/regexp/ locates the first
match of the expression in the file. (The form 0;// sets dot
unnecessarily.) ./regexp/// finds the second following occurrence of
the expression, and .,/regexp/ extends dot.
Commands
In the following, text demarcated by slashes represents text delimited
by any printable ASCII character except alphanumerics. Any number of
trailing delimiters may be elided, with multiple elisions then
representing null strings, but the first delimiter must always be
present. In any delimited text, newline may not appear literally; \n
may be typed for newline; and \/ quotes the delimiter, here /.
Backslash is otherwise interpreted literally, except in s commands.
Most commands may be prefixed by an address to indicate their range of
operation. Those that may not are marked with a * below. If a
command takes an address and none is supplied, dot is used. The sole
exception is the w command, which defaults to 0,$. In the
description, `range' is used to represent whatever address is
supplied. Many commands set the value of dot as a side effect. If
so, it is always set to the `result' of the change: the empty string
for a deletion, the new text for an insertion, etc. (but see the s and
e commands).
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Text commands
a/text/
or
a
lines of text
. Insert the text into the file after the range. Set dot.
c
i Same as a, but c replaces the text, while i inserts before the
range.
d Delete the text in the range. Set dot.
s/regexp/text/
Substitute text for the first match to the regular expression in
the range. Set dot to the modified range. In text the character
& stands for the string that matched the expression. Backslash
behaves as usual unless followed by a digit: \d stands for the
string that matched the subexpression begun by the d-th left
parenthesis. If s is followed immediately by a number n, as in
s2/x/y/, the n-th match in the range is substituted. If the
command is followed by a g, as in s/x/y/g, all matches in the
range are substituted.
m a1
t a1 Move the range to after a1 (m), or copy it (t). Set dot.
Display commands
p Print the text in the range. Set dot.
= Print the line address and character address of the range.
=# Print just the character address of the range.
File commands
* b file-list
Set the current file to the first file named in the list that sam
also has in its menu. The list may be expressed <shell command
in which case the file names are taken as words (in the shell
sense) generated by the shell command.
* B file-list
Same as b, except that file names not in the menu are entered
there, and all file names in the list are examined.
* n Print a menu of files. The format is:
' or blank indicating the file is modified or clean,
- or + indicating the file is unread or has been read (in
the terminal, * means more than one window is open),
. or blank indicating the current file,
a blank,
and the file name.
* D file-list
Delete the named files from the menu. If no files are named, the
current file is deleted. It is an error to D a modified file, but a
subsequent D will delete such a file.
I/O Commands
* e filename
Replace the file by the contents of the named external file. Set
dot to the beginning of the file.
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r filename
Replace the text in the range by the contents of the named
external file. Set dot.
w filename
Write the range (default 0,$) to the named external file.
* f filename
Set the file name and print the resulting menu entry.
If the file name is absent from any of these, the current file name is
used. e always sets the file name, r and w do so if the file has no
name.
< shell-command
Replace the range by the standard output of the shell command.
> shell-command
Sends the range to the standard input of the shell command.
| shell-command
Send the range to the standard input, and replace it by the
standard output, of the shell command.
* ! shell-command
Run the shell command.
* cd directory
Change working directory. If no directory is specified, $HOME is
used.
In any of <, >, | or !, if the shell command is omitted the last shell
command (of any type) is substituted. If sam is downloaded, ! sets
standard input to /dev/null, and otherwise unassigned output (stdout
for ! and >, stderr for all) is placed in $HOME/sam.err and the first
few lines are printed.
Loops and Conditionals
x/regexp/ command
For each match of the regular expression in the range, run the
command with dot set to the match. Set dot to the last match.
If the regular expression and its slashes are omitted, /.*\n/ is
assumed. Null string matches potentially occur before every
character of the range and at the end of the range.
y/regexp/ command
Like x, but run the command for each substring that lies before,
between, or after the matches that would be generated by x.
There is no default behavior. Null substrings potentially occur
before every character in the range.
* X/regexp/ command
For each file whose menu entry matches the regular expression,
make that the current file and run the command. If the
expression is omitted, the command is run in every file.
* Y/regexp/ command
Same as X, but for files that do not match the regular
expression, and the expression is required.
g/regexp/ command
v/regexp/ command
If the range contains (g) or does not contain (v) a match for the
expression, set dot to the range and run the command.
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These may be nested arbitrarily deeply, but only one instance of
either X or Y may appear in a single command. An empty command in an
x or y defaults to p; an empty command in X or Y defaults to f. g and
v do not have defaults.
Miscellany
k Set the current file's mark to the range. Does not set dot.
* q Quit. It is an error to quit with modified files, but a second q
will succeed.
* u n
Undo the last n (default 1) top-level commands that changed the
contents or name of the current file, and any other file whose
most recent change was simultaneous with the current file's
change. Successive u's move further back in time. The only
commands for which u is ineffective are cd, u, q, w and D.
(empty)
If the range is explicit, set dot to the range. If sam is
downloaded, the resulting dot is selected on the screen;
otherwise it is printed. If no address is specified (the command
is a newline) dot is extended in either direction to line
boundaries and printed. If dot is thereby unchanged, it is set
to .+1 and printed.
Grouping and multiple changes
Commands may be grouped by enclosing them in braces {}. Commands
within the braces must appear on separate lines (no backslashes are
required between commands). Semantically, an opening brace is like a
command: it takes an (optional) address and sets dot for each sub-
command. Commands within the braces are executed sequentially, but
changes made by one command are not visible to other commands (see the
next paragraph). Braces may be nested arbitrarily.
When a command makes a number of changes to a file, as in
x/re/c/text/, the addresses of all changes to the file are computed in
the original file. If the changes are in sequence, they are applied
to the file. Successive insertions at the same address are catenated
into a single insertion composed of the several insertions in the
order applied.
The terminal
What follows refers to behavior of sam when downloaded, that is, when
operating as a display editor on a bitmap display. This is the
default behavior; invoking sam with the -d (no download) option
provides access to the command language only.
Each file may have zero or more windows open. Each window is
equivalent and is updated simultaneously with changes in other windows
on the same file. Each window has an independent value of dot,
indicated by a highlighted substring on the display. Dot may be in a
region not within the window. There is usually a `current window',
marked with a dark border, to which typed text and editing commands
apply. The escape key (ESC) selects (sets dot to) text typed since
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the last mouse button hit.
The button 3 menu controls window operations. The top of the menu
provides the following operators, each of which uses one or more
cursors to prompt for selection of a window or sweeping of a
rectangle.
new Create a new, empty file: Depress button 3 where one corner of
the new rectangle should appear (box cursor), and move the mouse
while holding down button 3 to the diagonally opposite corner.
`Sweeping' a null rectangle gets a large window, disjoint from
the command window or the whole sam window, depending on where
the null rectangle is.
xerox
Create a copy of an existing window. After selecting the window
to copy with button 1, sweep out the window for the copy.
reshape
Change the size and location of a window. First click button 3
in the window to be changed (gunsight cursor). Then sweep out a
window as for the new menu selection.
close
Delete the window. In the last window of a file, close is
equivalent to a D for the file.
write
Equivalent to a w for the file.
Below these operators is a list of available files, starting with
~~sam~~, the command window. Selecting a file from the list makes the
most recently used window on that file current, unless it is already
current, in which case selections cycle through the open windows. If
no windows are open on the file, the user is prompted to open one.
Files other than ~~sam~~ are marked with one of the characters -+*
according as zero, one, or more windows are open on the file. A
further mark . appears on the file in the current window and a single
quote, ', on a file modified since last write.
The command window, created automatically when sam starts, is an
ordinary window except that text typed to it is interpreted as
commands for the editor rather than passive text, and text printed by
editor commands appears in it. There is an `output point' that
separates commands being typed from previous output. Commands typed
in the command window apply to the current open file-the file in the
most recently current window.
Manipulating text
Typed characters replace the current selection (dot) in the current
window. Backspace deletes the previous character. Escape selects
(sets dot to) everything typed since the last mouse hit.
Button 1 changes selection. Pointing to a non-current window with
button 1 makes it current; within the current window, button 1 selects
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text, thus setting dot. Double-clicking selects text to the
boundaries of words, lines, quoted strings or bracketed strings,
depending on the text at the click.
Button 2 provides a menu of editing commands:
cut Delete dot and save the deleted text in the snarf buffer.
paste Replace the text in dot by the contents of the snarf buffer.
snarf Save the text in dot in the snarf buffer.
look Search forward for the next occurrence of the literal text in
dot. If dot is the null string, the text in the snarf buffer
is used. The snarf buffer is unaffected.
<exch> Exchange the snarf buffer with the current selection in
another X11 window. The exchange of a large amount of
selected text is truncated to the size of Sam's internal
snarf buffer (currently 4K) without warning.
/regexp Search forward for the next match of the last regular
expression typed in a command. (Not in command window.)
send Send the text in dot, or the snarf buffer if dot is the null
string, as if it were typed to the command window. Saves the
sent text in the snarf buffer. (Command window only.)
X11 resources
Various attributes of sam can be set by giving values to X11 resources
for the class Sam. There are various ways to do this; one is to have a
file called Sam in your home directory, with entries in it like:
Sam*width: 500
Sam*height: 600
Sam*font: fixed
Sam*scrollForwardR: true
In addition to the usual X11 toolkit resources, the scrollForwardR
resource says where the right button (button 3) scrolls forward or
backward in the file.
Abnormal termination
If sam terminates other than by a q command (by hangup, deleting its
window, etc.), modified files are saved in an executable file,
$HOME/sam.save. This program, when executed, asks whether to write
each file back to a external file. The answer y causes writing;
anything else skips the file. If a machine crash prevents the
creation of a sam.save file, all changes are lost. If an editing
session is difficult to replicate, you should write your changed files
often.
B is a shell-level command that causes an instance of sam running on
the same terminal to load the named files. The option allows a line
number to be specified for the initial position to display in the last
named file.
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FILES
$HOME/sam.save
$HOME/sam.err
<system-dependent dirctory>/samsave the program called to unpack
$home/sam.save.
SEE ALSO
ed(1), regexp(6)
BUGS
When a sam window is resized, the command window may have the wrong
size.
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