sed(1)                      General Commands Manual                     sed(1)



NAME
       sed - the stream editor

SYNOPSIS
       sed [-n] [-g] [-e script ] [-f sfile ] [ file ] ...

DESCRIPTION
       Sed  copies  the  named  files (standard input default) to the standard
       output, edited according to a script of commands.

       An -e option supplies a single edit command from the next argument;  if
       there  are  several  of  these they are executed in the order in  which
       they appear. If there is just one -e option and no -f 's, the -e   flag
       may be omitted.

       An  -f  option  causes  commands to be taken from the file "sfile";  if
       there are several  of these they are  executed in the order  in   which
       they appear; -e and -f commands may be mixed.

       The  -g option causes sed to act as though every substitute  command in
       the script has a g suffix.

       The -n option suppresses the default output.

       A script consists of commands, one per line, of the following form:

            [address [, address] ] function [arguments]

       Normally sed cyclically copies a line of input  into  a   current  text
       buffer,  then applies all commands whose addresses select the buffer in
       sequence, then copies the buffer to standard output and clears it.

       The -n option suppresses normal output (so that only p and w output  is
       done).  Also,  some  commands  (n, N) do their own line reads, and some
       others (d, D) cause all commands following in the script to be  skipped
       (the  D command also suppresses the clearing of the current text buffer
       that would normally occur before the next cycle).

       It is also helpful to know that there's a  second  buffer  (called  the
       `hold  space' that can be copied or appended to or from or swapped with
       the current text buffer.

       An address is: a decimal numeral (which matches  the  line  it  numbers
       where  line numbers start at 1 and run cumulatively across files), or a
       `$' that addresses the last line of input, or a context address,  which
       is a `/regular expression/', in the style of ed (1) modified thus:

       (1)  The  escape  sequence `\n'  matches a newline embedded in the buf-
            fer, and `\t' matches a tab.

       (2)  A command line with no addresses selects every buffer.

       (3)  A command line with one address selects every buffer that  matches
            that address.

       (4)  A command line with two addresses selects the inclusive range from
            the first input buffer  that matches the first address through the
            next input buffer  that matches the second. (If the second address
            is a number less than or equal to the line number first  selected,
            only one line is selected.) Once the second address is matched sed
            starts looking for the first one again; thus,  any number of these
            ranges will be matched.

       The  negation  operator  '!'  can prefix a command to apply it to every
       line not selected by the address(es).

       In the following list of functions, the  maximum  number  of  addresses
       permitted for each function is indicated in parentheses.

       An argument denoted "text" consists of one or more lines,  with all but
       the last ending with `' to hide the newline.

       Backslashes in text are treated like  backslashes  in  the  replacement
       string  of an `s' command and may be used to protect initial whitespace
       (blanks and tabs) against the stripping that is done on every line   of
       the script.

       An  argument  denoted  "rfile"  or "wfile"  must be last on the command
       line. Each wfile is created before processing begins.  There can be  at
       most 10 distinct wfile arguments.

       a "text"   (1)
            Append. Place text on output before reading the next input line.

       b "label"  (2)
            Branch  to  the  `:'  command  bearing  the label.  If no label is
            given, branch to the end of the script.

       c "text"   (2)
            Change. Delete the current text buffer.  With 0 or 1 address,   or
            at  the end of a 2-address range, place text on the output.  Start
            the next cycle.

       d          (2)
            Delete the current text buffer. Start the next cycle.

       D          (2)
            Delete the first line of the current text buffer (all chars up  to
            the first newline). Start the next cycle.

       g          (2)
            Replace  the contents of the current text buffer with the contents
            of the hold space.

       G          (2)
            Append the contents of the hold space to the current text buffer.

       h          (2)
            Copy the current text buffer into the hold space.

       H          (2)
            Append a copy of the current text buffer to the hold space.

       i "text"   (1)
            Insert. Place text on the standard output.

       l          (2)
            List. Sends the pattern space to standard output.   A  "w"  option
            may  follow  as  in  the s command below. Non-printable characters
            expand to:

               \b  --  backspace (ASCII 08)
               \t  --  tab       (ASCII 09)
               \n  --  newline   (ASCII 10)
               \r  --  return    (ASCII 13)
               \e  --  escape    (ASCII 27)
               \xx --  the ASCII character corresponding to 2 hex digits xx.

       Dump.  Hex-dump the pattern space to standard output.

       n          (2)
            Copy the current text buffer to standard  output.  Read  the  next
            line of input into it.

       N          (2)
            Append  the next line of input to the current text buffer, insert-
            ing an embedded newline between the two. The current  line  number
            changes.

       p          (2)
            Print. Copy the current text buffer to the standard output.

       P          (2)
            Copy  the  first  line of the current text buffer (all chars up to
            the first newline) to standard output.

       q          (1)
            Quit. Branch to the end of the script. Do not start a new cycle.

       r "rfile"  (1)
            Read the contents of rfile. Place them on the output before  read-
            ing the next input line.

       s /regular expression/replacement/flags         (2)
            Substitute  the  replacement for instances of the regular  expres-
            sion in the current  text  buffer.   Any  character  may  be  used
            instead  of  `/'.   For a fuller description see ed (1).  Flags is
            zero or more of the following:

            g -- Global. Substitute for all nonoverlapping  instances  of  the
            string
                 rather than just the first one.

            p -- Print the pattern space if a replacement was made.

            w  --  Write. Append the current text buffer to a file argument as
            in  a
                 w command if a replacement is made. Standard output  is  used
            if no
                 file argument is given


       t "label"  (2)
            Branch-if-test.  Branch  to  the : command with the given label if
            any substitutes have been made since the most recent  read  of  an
            input  line  or  execution  of a `t'or `T'.  If no label is given,
            branch to the end of the script.

       T "label"  (2)
            Branch-on-error. Branch to the : command with the given  label  if
            no  substitutes have succeeded since the last input line or t or T
            command.  Branch to the end of the script if no label is given.

       w "wfile"  (2)
            Write. Append the current text buffer to wfile .

       W "wfile"  (2)
            Write first line.  Append first line  of the current  text  buffer
            to wfile.

       x          (2)
            Exchange the contents of the current text buffer and hold space.

       y /string1/string2/      (2)
            Translate.  Replace  each  occurrence  of  a character  in string1
            with the corresponding  character  in  string2.   The  lengths  of
            these strings must be equal.

       ! "command"              (2)
            All-but.   Apply  the function (or group, if function is `{') only
            to lines not selected by the address(es).

       : "label"  (0)
            This command does nothing but hold a label for `b'  and  `t'  com-
            mands to branch to.

       =          (1)
            Place the current line number on the standard output as a line.

       {          (2)
            Execute  the  following  commands through a matching `}' only when
            the current line matches the address or address range given.

       An empty command is ignored.

PORTABILITY
       This tool was reverse-engineered from BSD 4.1 UNIX sed, and (as far  as
       the author's knowledge and tests can determine) is compatible  with it.
       All documented features of BSD 4.1 sed are supported.

       One undocumented feature (a leading 'n' in the first comment having the
       same effect as an  -n command-line option)  has been omitted.

       The following bugs and limitations have been fixed:

       *    There is no hidden length limit (40 in BSD sed) on w file names.

       *    There is no limit (8 in BSD sed) on the length of labels.

       *    The exchange command now works for long pattern and hold spaces.

       The following enhancements to existing commands have been made:

       *    a, i commands don't insist on a leading backslash-\n in the text.

       *    r, w commands don't insist on whitespace before the filename.

       *    The g, p and P options on s commands may be given in any order.

       Some enhancements to regular-expression syntax have been made:

       *    \t is recognized in REs (and elswhere) as an escape for tab.

       *    In an RE, + calls for 1..n repeats of the previous pattern.

       The following are completely new features:

       *    The l command (list, undocumented and weaker in BSD)

       The 'L' command (hex dump).

       *    The W command (write first line of pattern space to file).

       *    The T command (branch on last substitute failed).

       *    Trailing comments are now allowed on command lines.

       In  addition,   sed's  error  messages have been made more specific and
       informative.

       The implementation is also  significantly  smaller and  faster than BSD
       4.1 sed. It uses only the standard I/O library and exit(3).

SEE ALSO
       ed(1), grep(1), awk(1), lex(1), regexp(5)

AUTHOR
       Eric  S.  Raymond  <esr@snark.thyrsus.com>  and  Rene Rebe <rene@exact-
       code.de>.  This program is distributed under a BSD-like license.




                               October 15, 2021                         sed(1)
