# 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  buffer,
              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.

         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,  inserting
              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 reading
              the next input line.

         s /regular-expression/replacement/flags      (2)
              Substitute the replacement for instances of the  regular  expression
              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  commands  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:

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

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

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

         The following enhancements to existing commands have been made:

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

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

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

         Some enhancements to regular-expression syntax have been made:

         o    \t is recognized in REs (and elsewhere) as an escape for tab.

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

         The following are completely new features:

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

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

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

         o    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).

    NOTE

         This is a freeware component of the GNU and MINIX operating systems.  The
         user   is  hereby  granted  permission  to  use,  modify,  reproduce  and
         distribute it subject to the following conditions:

         1. The authorship notice appearing in each source file may not be altered
         or deleted.

         2. The object form may not be distributed without source.

    SEE ALSO

         cgrep(1), fgrep(1), grep(1), lex(1), regexp(5), awk(9).

    AUTHOR
         Eric S. Raymond <esr@snark.thyrsus.com>