sam

SAM(1plan9)                                                          SAM(1plan9)



NAME
       sam, B, E, sam.save, samterm, samsave - screen editor with structural
       regular expressions

SYNOPSIS
       sam [ option ...  ] [ files ]

       sam -r machine

       sam.save

       B file[:line] ...

       E 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

       -a     Autoindent.  In this mode, when a newline character is typed in
              the terminal interface, samterm copies leading white space on the
              current line to the new line.

       -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 path
              Start the host part from the specified file on the remote host.
              Only meaningful with the -r option.

       -t path
              Start the terminal part from the specified file.  Useful for
              debugging.

   Regular expressions
       Regular expressions are as in regexp(7) with the addition of \n to
       represent newlines.  A regular expression may never contain a literal
       newline character.  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 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; 0 is the beginning of the file.
       /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).

       "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 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 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).

   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 (m) or copy (t) the range to after a1.  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 <Plan 9 command
              in which case the file names are taken as words (in the shell
              sense) generated by the Plan 9 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.
       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.
       < Plan 9-command
              Replace the range by the standard output of the Plan 9 command.
       > Plan 9-command
              Send the range to the standard input of the Plan 9 command.
       | Plan 9-command
              Send the range to the standard input, and replace it by the
              standard output, of the Plan 9 command.
       * ! Plan 9-command
              Run the Plan 9 command.
       * cd directory
              Change working directory.  If no directory is specified, $home is
              used.

       In any of <, >, | or !, if the Plan 9 command is omitted the last Plan 9
       command (of any type) is substituted.  If sam is downloaded (using the
       mouse and raster display, i.e. not using option -d), !  sets standard
       input to /dev/null, and otherwise unassigned output (stdout for !  and >,
       stderr for all) is placed in /tmp/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, 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 regular expression.  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.
       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.  If n
              is negative, u `redoes,' undoing the undo, going forwards in time
              again.

       (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 raster 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.  Text may be
       typed and edited as in rio(1); also the escape key (ESC) selects (sets
       dot to) text typed since 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 rio-like
       cursors to prompt for selection of a window or sweeping of a rectangle.
       `Sweeping' a null rectangle gets a large window, disjoint from the
       command window or the whole screen, depending on where the null rectangle
       is.

       new    Create a new, empty file.

       zerox  Create a copy of an existing window.

       resize As in rio.

       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.  The behavior is like rio, with 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
       Button 1 changes selection, much like rio.  Pointing to a non-current
       window with button 1 makes it current; within the current window, button
       1 selects 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.

       plumb  Send the text in the selection as a plumb message.  If the
              selection is empty, the white-space-delimited block of text is
              sent as a plumb message with a click attribute defining where the
              selection lies (see plumb(7)).

       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.

       <rio>  Exchange snarf buffers with rio.

       /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.)

   External communication
       Sam listens to the edit plumb port.  If plumbing is not active, on
       invocation sam creates a named pipe /srv/sam.user which acts as an
       additional source of commands.  Characters written to the named pipe are
       treated as if they had been typed in the command window.

       B is a shell-level command that causes an instance of sam running on the
       same terminal to load the named files.  B uses either plumbing or the
       named pipe, whichever service is available.  If plumbing is not enabled,
       the option allows a line number to be specified for the initial position
       to display in the last named file (plumbing provides a more general
       mechanism for this ability).

       E is a shell-level command that can be used as $EDITOR in a Unix
       environment.  It runs B on file and then does not exit until file is
       changed, which is taken as a signal that file is done being edited.

   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 causes writing; anything else
       skips the file.

FILES
       $HOME/sam.save

       $HOME/sam.err

       /bin/samsave
              the program called to unpack $HOME/sam.save.

SOURCE
       /src/cmd/sam
              source for sam itself

       /src/cmd/samterm
              source for the separate terminal part

       /bin/B

       /bin/E

SEE ALSO
       ed(1), sed(1), grep(1), rio(1), regexp(7).

       Rob Pike, ``The text editor sam''.



                                                                     SAM(1plan9)