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NAME

       sed - stream editor

SYNOPSIS

       sed [ -gln ] [ -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.  The -f option causes the script to be taken from  file
       sfile;  these options accumulate.  If there is just one -e option and no -f's, the flag -e
       may be omitted.  The -n option suppresses the default output; -g causes all  substitutions
       to be global, as if suffixed g.  The -l option causes sed to flush its output buffer after
       every newline.

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

              [address [, address] ] function [argument ...]

       In normal operation sed cyclically copies a line of input into  a  pattern  space  (unless
       there is something left after a command), applies in sequence all commands whose addresses
       select that pattern space, and at the end of the script copies the pattern  space  to  the
       standard output (except under -n) and deletes the pattern space.

       An address is either a decimal number that counts input lines cumulatively across files, a
       that addresses the last line of input, or a context address, /regular-expression/, in  the
       style  of  regexp(7),  with  the  added  convention that matches a newline embedded in the
       pattern space.

       A command line with no addresses selects every pattern space.

       A command line with one address selects each pattern space that matches the address.

       A command line with two addresses selects the inclusive range from the first pattern space
       that  matches  the  first  address through the next pattern space 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.)  Thereafter the process is repeated, looking again for the
       first address.

       Editing commands can be applied to non-selected pattern spaces  by  use  of  the  negation
       function (below).

       An argument denoted text consists of one or more lines, all but the last of which end with
       to hide the newline.  Backslashes in text are treated like backslashes in the  replacement
       string  of  an  command,  and  may  be used to protect initial blanks and tabs against the
       stripping that is done on every script line.

       An argument denoted rfile or wfile must terminate the command line and must be preceded by
       exactly  one blank.  Each wfile is created before processing begins.  There can be at most
       120 distinct wfile arguments.

       a\
       text         Append.  Place text on the output before reading the next input line.

       b label      Branch to the : command bearing the label.  If label is empty, branch to  the
                    end of the script.

       c\
       text         Change.   Delete  the  pattern space.  With 0 or 1 address or at the end of a
                    2-address range, place text on the output.  Start the next cycle.

       d            Delete the pattern space.  Start the next cycle.

       D            Delete the initial segment of the pattern space through  the  first  newline.
                    Start the next cycle.

       g            Replace the contents of the pattern space by the contents of the hold space.

       G            Append the contents of the hold space to the pattern space.

       h            Replace the contents of the hold space by the contents of the pattern space.

       H            Append the contents of the pattern space to the hold space.

       i\
       text         Insert.  Place text on the standard output.

       n            Copy  the  pattern  space  to the standard output.  Replace the pattern space
                    with the next line of input.

       N            Append the next line of input to the pattern space with an embedded  newline.
                    (The current line number changes.)

       p            Print.  Copy the pattern space to the standard output.

       P            Copy  the  initial  segment of the pattern space through the first newline to
                    the standard output.

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

       r rfile      Read the contents of rfile.  Place them on the output before reading the next
                    input line.

       s/regular-expression/replacement/flags
                    Substitute  the replacement string for instances of the regular-expression in
                    the pattern space.  Any character  may  be  used  instead  of  For  a  fuller
                    description see regexp(7).  Flags is zero or more of

                    g      Global.   Substitute  for all non-overlapping instances of the regular
                           expression rather than just the first one.

                    p      Print the pattern space if a replacement was made.

                    w wfile
                           Write.  Append the pattern space to wfile if a replacement was made.

       t label      Test.  Branch to the command bearing the label if any substitutions have been
                    made  since  the  most  recent  reading of an input line or execution of a If
                    label is empty, branch to the end of the script.

       w            wfile
                    Write.  Append the pattern space to wfile.

       x            Exchange the contents of the pattern and hold spaces.

       y/string1/string2/
                    Transform.  Replace  all  occurrences  of  characters  in  string1  with  the
                    corresponding  character in string2.  The lengths of string1 and string2 must
                    be equal.

       !function    Don't.  Apply the function (or group,  if  function  is  only  to  lines  not
                    selected by the address(es).

       : label      This  command  does  nothing; it bears a label for b and t commands to branch
                    to.

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

       {            Execute the following commands through a matching only when the pattern space
                    is selected.

                    An empty command is ignored.

EXAMPLES

       sed 10q file
              Print the first 10 lines of the file.

       sed '/^$/d'
              Delete empty lines from standard input.

       sed 's/UNIX/& system/g'
              Replace every instance of by

       sed 's/ *$//   drop trailing blanks
       /^$/d               drop empty lines
       s/  */\        replace blanks by newlines
       /g
       /^$/d' chapter*
              Print the files chapter1, chapter2, etc. one word to a line.

       nroff -ms manuscript | sed '
       ${
            /^$/p          if last line of file is empty, print it
       }
       //N            if current line is empty, append next line
       /^\n$/D'       if two lines are empty, delete the first
              Delete all but one of each group of empty lines from a formatted manuscript.

SOURCE

       /src/cmd/sed.c

SEE ALSO

       ed(1), grep(1), awk(1), lex(1), sam(1), regexp(7)
       L.  E.  McMahon,  `SED — A Non-interactive Text Editor', Unix Research System Programmer's
       Manual, Volume 2.

BUGS

       If input is from a pipe, buffering may consume characters beyond a line on which a command
       is executed.

                                                                                           SED(1)