SED(1)                     OpenBSD Reference Manual                     SED(1)

NAME
     sed - stream editor

SYNOPSIS
     sed [-aEnru] command [file ...]
     sed [-aEnru] [-e command] [-f command_file] [file ...]

DESCRIPTION
     The sed utility reads the specified files, or the standard input if no
     files are specified, modifying the input as specified by a list of com-
     mands.  The input is then written to the standard output.

     A single command may be specified as the first argument to sed.  Multiple
     commands may be specified separated by newlines or semicolons, or by us-
     ing the -e or -f options.  All commands are applied to the input in the
     order they are specified regardless of their origin.

     The options are as follows:

     -a      The files listed as parameters for the `w' functions are created
             (or truncated) before any processing begins, by default.  The -a
             option causes sed to delay opening each file until a command con-
             taining the related `w' function is applied to a line of input.

     -E      Interpret regular expressions using POSIX extended regular ex-
             pression syntax.  The default behaviour is to use POSIX basic
             regular expression syntax.

     -e command
             Append the editing commands specified by the command argument to
             the list of commands.

     -f command_file
             Append the editing commands found in the file command_file to the
             list of commands.  The editing commands should each be listed on
             a separate line.

     -r      An alias for -E, for compatibility with GNU sed.

     -n      By default, each line of input is echoed to the standard output
             after all of the commands have been applied to it.  The -n option
             suppresses this behavior.

     -u      Force output to be line buffered, printing each line as it be-
             comes available.  By default, output is line buffered when stan-
             dard output is a terminal and block buffered otherwise.  See
             setbuf(3) for a more detailed explanation.

     The form of a sed command is as follows:

           [address[,address]]function[arguments]

     Whitespace may be inserted before the first address and the function por-
     tions of the command.

     Normally, sed cyclically copies a line of input, not including its termi-
     nating newline character, into a pattern space, (unless there is some-
     thing left after a `D' function), applies all of the commands with ad-
     dresses that select that pattern space, copies the pattern space to the
     standard output, appending a newline, and deletes the pattern space.

     Some of the functions use a hold space to save all or part of the pattern
     space for subsequent retrieval.

SED ADDRESSES
     An address is not required, but if specified must be a number (that
     counts input lines cumulatively across input files), a dollar character
     (`$') that addresses the last line of input, or a context address (which
     consists of a regular expression preceded and followed by a delimiter).

     A command line with no addresses selects every pattern space.

     A command line with one address selects all of the pattern spaces that
     match 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 pat-
     tern space that matches the second.  (If the second address is a number
     less than or equal to the line number first selected, only that line is
     selected.)  Starting at the first line following the selected range, sed
     starts looking again for the first address.

     Editing commands can be applied to non-selected pattern spaces by use of
     the exclamation character (`!') function.

SED REGULAR EXPRESSIONS
     By default, sed regular expressions are basic regular expressions (BREs).
     Extended regular expressions are supported using the -E and -r options.
     See re_format(7) for more information on regular expressions.  In addi-
     tion, sed has the following two additions to BREs:

     1.   In a context address, any character other than a backslash (`\') or
          newline character may be used to delimit the regular expression.
          The opening delimiter should be preceded by a backslash unless it is
          a slash.  Putting a backslash character before the delimiting char-
          acter causes the character to be treated literally.  For example, in
          the context address \xabc\xdefx, the RE delimiter is an `x' and the
          second `x' stands for itself, so that the regular expression is
          ``abcxdef''.

     2.   The escape sequence \n matches a newline character embedded in the
          pattern space.  You can't, however, use a literal newline character
          in an address or in the substitute command.

     One special feature of sed regular expressions is that they can default
     to the last regular expression used.  If a regular expression is empty,
     i.e., just the delimiter characters are specified, the last regular ex-
     pression encountered is used instead.  The last regular expression is de-
     fined as the last regular expression used as part of an address or sub-
     stitute command, and at run-time, not compile-time.  For example, the
     command ``/abc/s//XXX/'' will substitute ``XXX'' for the pattern ``abc''.

SED FUNCTIONS
     In the following list of commands, the maximum number of permissible ad-
     dresses for each command is indicated by [0addr], [1addr], or [2addr],
     representing zero, one, or two addresses.

     The argument text consists of one or more lines.  To embed a newline in
     the text, precede it with a backslash.  Other backslashes in text are
     deleted and the following character taken literally.

     The `r' and `w' functions take an optional file parameter, which should
     be separated from the function letter by whitespace.  Each file given as
     an argument to sed is created (or its contents truncated) before any in-
     put processing begins.

     The `b', `r', `s', `t', `w', `y', `!', and `:' functions all accept addi-
     tional arguments.  The following synopses indicate which arguments have
     to be separated from the function letters by whitespace characters.

     Two of the functions take a function-list.  This is a list of sed func-
     tions separated by newlines, as follows:

           { function
             function
             ...
             function
           }

     The `{' can be preceded or followed by whitespace.  The function can be
     preceded by whitespace as well.  The terminating `}' must be preceded by
     a newline or optional whitespace.

     [2addr] function-list
               Execute function-list only when the pattern space is selected.

     [1addr]a\
     text

               Write text to standard output immediately before each attempt
               to read a line of input, whether by executing the `N' function
               or by beginning a new cycle.

     [2addr]b[label]
               Branch to the `:' function with the specified label.  If the
               label is not specified, branch to the end of the script.

     [2addr]c\
     text

               Delete the pattern space.  With 0 or 1 address or at the end of
               a 2-address range, text is written to the standard output.

     [2addr]d  Delete the pattern space and start the next cycle.

     [2addr]D  Delete the initial segment of the pattern space through the
               first newline character and start the next cycle.

     [2addr]g  Replace the contents of the pattern space with the contents of
               the hold space.

     [2addr]G  Append a newline character followed by the contents of the hold
               space to the pattern space.

     [2addr]h  Replace the contents of the hold space with the contents of the
               pattern space.

     [2addr]H  Append a newline character followed by the contents of the pat-
               tern space to the hold space.

     [1addr]i\
     text

               Write text to the standard output.

     [2addr]l  (The letter ell.)  Write the pattern space to the standard out-
               put in a visually unambiguous form.  This form is as follows:

                     backslash          \\
                     alert              \a
                     backspace          \b
                     form-feed          \f
                     carriage-return    \r
                     tab                \t
                     vertical tab       \v

               Non-printable characters are written as three-digit octal num-
               bers (with a preceding backslash) for each byte in the charac-
               ter (most significant byte first).  Long lines are folded, with
               the point of folding indicated by displaying a backslash fol-
               lowed by a newline.  The end of each line is marked with a `$'.

     [2addr]n  Write the pattern space to the standard output if the default
               output has not been suppressed, and replace the pattern space
               with the next line of input.

     [2addr]N  Append the next line of input to the pattern space, using an
               embedded newline character to separate the appended material
               from the original contents.  Note that the current line number
               changes.

     [2addr]p  Write the pattern space to standard output.

     [2addr]P  Write the pattern space, up to the first newline character to
               the standard output.

     [1addr]q  Branch to the end of the script and quit without starting a new
               cycle.

     [1addr]r file
               Copy the contents of file to the standard output immediately
               before the next attempt to read a line of input.  If file can-
               not be read for any reason, it is silently ignored and no error
               condition is set.

     [2addr]s/re/replacement/flags
               Substitute the replacement string for the first instance of the
               regular expression in the pattern space.  Any character other
               than backslash or newline can be used instead of a slash to de-
               limit the RE and the replacement.  Within the RE and the re-
               placement, the RE delimiter itself can be used as a literal
               character if it is preceded by a backslash.

               An ampersand (`&') appearing in the replacement is replaced by
               the string matching the RE.  The special meaning of `&' in this
               context can be suppressed by preceding it by a backslash.  The
               string `\#', where `#' is a digit, is replaced by the text
               matched by the corresponding backreference expression (see
               re_format(7)).

               A line can be split by substituting a newline character into
               it.  To specify a newline character in the replacement string,
               precede it with a backslash.

               The value of flags in the substitute function is zero or more
               of the following:

                     0 ... 9
                             Make the substitution only for the N'th occur-
                             rence of the regular expression in the pattern
                             space.

                     g       Make the substitution for all non-overlapping
                             matches of the regular expression, not just the
                             first one.

                     p       Write the pattern space to standard output if a
                             replacement was made.  If the replacement string
                             is identical to that which it replaces, it is
                             still considered to have been a replacement.

                     w file  Append the pattern space to file if a replacement
                             was made.  If the replacement string is identical
                             to that which it replaces, it is still considered
                             to have been a replacement.

     [2addr]t[label]
               Branch to the `:' function bearing the label if any substitu-
               tions have been made since the most recent reading of an input
               line or execution of a `t' function.  If no label is specified,
               branch to the end of the script.

     [2addr]w file
               Append the pattern space to the file.

     [2addr]x  Swap the contents of the pattern and hold spaces.

     [2addr]y/string1/string2/
               Replace all occurrences of characters in string1 in the pattern
               space with the corresponding characters from string2.  Any
               character other than a backslash or newline can be used instead
               of a slash to delimit the strings.  Within string1 and string2,
               a backslash followed by any character other than a newline is
               that literal character, and a backslash followed by an `n' is
               replaced by a newline character.

     [2addr]!function, [2addr]!function-list
               Apply the function or function-list only to the lines that are
               not selected by the address(es).

     [0addr]:label
               This function does nothing; it bears a label to which the `b'
               and `t' commands may branch.

     [1addr]=  Write the line number to the standard output followed by a new-
               line character.

     [0addr]   Empty lines are ignored.

     [0addr]#  The `#' and the remainder of the line are ignored (treated as a
               comment), with the single exception that if the first two char-
               acters in the file are `#n', the default output is suppressed.
               This is the same as specifying the -n option on the command
               line.

     The sed utility exits 0 on success, and >0 if an error occurs.

SEE ALSO
     awk(1), ed(1), grep(1), regex(3), setbuf(3), re_format(7)

STANDARDS
     The sed utility is compliant with the IEEE Std 1003.1-2008 (``POSIX'')
     specification.

     The flags [-aEru] are extensions to that specification.

     The use of newlines to separate multiple commands on the command line is
     non-portable; the use of newlines to separate multiple commands within a
     command file (-f command_file) is portable.

HISTORY
     A sed command appeared in Version 7 AT&T UNIX.

CAVEATS
     The use of semicolons to separate multiple commands is not permitted for
     the following commands: a, b, c, i, r, t, w, :, and #.

OpenBSD 4.7                    January 10, 2010                              5
