SED(1)                      General Commands Manual                     SED(1)


     sed - stream editor


     sed [-aEnru] [-i[extension]] command [file ...]
     sed [-aEnru] [-e command] [-f command_file] [-i[extension]] [file ...]


     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
     commands.  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
     using 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 function or flag are
             created (or truncated) before any processing begins, by default.
             The -a option causes sed to delay opening each file until a
             command containing the related w function or flag is applied to a
             line of input.

     -E      Interpret regular expressions using POSIX extended regular
             expression 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.

             Edit files in place, saving backups with the specified extension.
             If a zero length extension is given, no backup will be saved.  It
             is not recommended to give a zero length extension when in place
             editing files, as it risks corruption or partial content in
             situations where disk space is exhausted, etc.

     -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
             becomes available.  By default, output is line buffered when
             standard output is a terminal and block buffered otherwise.  See
             setvbuf(3) for a more detailed explanation.

     The form of a sed command is as follows:


     Whitespace may be inserted before the first address and the function
     portions of the command.

     Normally, sed cyclically copies a line of input, not including its
     terminating newline character, into a pattern space, (unless there is
     something left after a D function), applies all of the commands with
     addresses 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.


     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
     is a regular expression preceded and followed by a delimiter.  The
     delimiter can be any character except a newline or a backslash.  Unless
     it is a slash, the opening delimiter needs to be escaped with a

     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
     pattern 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.


     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
     addition, sed has the following two additions to BREs:

     1.   The character delimiting the regular expression can be used inside
          the regular expression by prepending a backslash or by including it
          in a character class.  For example, in the context address
          \x\x[xy]x, the RE delimiter is an `x' and the other `x' characters
          stand for themselves, so that the regular expression is "x[xy]".

     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
     expression encountered is used instead.  The last regular expression is
     defined as the last regular expression used as part of an address or
     substitute command, and at run-time, not compile-time.  For example, the
     command "/abc/s//XXX/" will substitute "XXX" for the pattern "abc".


     In the following list of commands, the maximum number of permissible
     addresses 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, as well as the w flag to the s function, take a
     file parameter, which should be separated from the function or flag by
     whitespace.  Files are created (or their contents truncated) before any
     input processing begins.

     The b, r, s, t, w, y, and : functions all accept additional arguments.
     The synopses below indicate which arguments have to be separated from the
     function letters by whitespace characters.

     Functions can be combined to form a function list, a list of sed
     functions each followed by a newline, as follows:

           { function

     The braces can be preceded and followed by whitespace.  The functions can
     be preceded by whitespace as well.

     Functions and function lists may be preceded by an exclamation mark, in
     which case they are applied only to lines that are not selected by the

             Execute function-list only when the pattern space is selected.

             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.

             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.

             Delete the pattern space and start the next cycle.

             Delete the initial segment of the pattern space through the first
             newline character and start the next cycle.

             Replace the contents of the pattern space with the contents of
             the hold space.

             Append a newline character followed by the contents of the hold
             space to the pattern space.

             Replace the contents of the hold space with the contents of the
             pattern space.

             Append a newline character followed by the contents of the
             pattern space to the hold space.

             Write text to the standard output.

             (The letter ell.)  Write the pattern space to the standard output
             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 numbers
             (with a preceding backslash) for each byte in the character (most
             significant byte first).  Long lines are folded, with the point
             of folding indicated by displaying a backslash followed by a
             newline.  The end of each line is marked with a `$'.

             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.

             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

             Write the pattern space to standard output.

             Write the pattern space, up to the first newline character, to
             the standard output.

             Branch to the end of the script and quit without starting a new

     [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 cannot
             be read for any reason, it is silently ignored and no error
             condition is set.

             Substitute the replacement string for the first instance of the
             regular expression RE in the pattern space.  Any character other
             than backslash or newline can be used instead of a slash to
             delimit the regular expression and the replacement.  Also see the
             the section about SED REGULAR EXPRESSIONS.

             An ampersand (`&') appearing in the replacement is replaced by
             the string matching the regular expression.  The string `\#',
             where `#' is a digit, is replaced by the text matched by the
             corresponding backreference expression (see re_format(7)).

             All other instances of a backslash will print the literal
             character following it.  Using a backslash before any other
             character other than `&', `\', digit, newline (ascii 0x0a), and
             the delimiter is unspecified and might not be portable to other
             implementations of sed.

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

                   N       Make the substitution only for the N'th occurrence
                           of the regular expression in the pattern space,
                           where N is a positive integer starting with 1 ...

                   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 substitutions
             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.

             Swap the contents of the pattern and hold spaces.

             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 another
             backslash is replaced by a single backslash, a backslash followed
             by an `n' is replaced by a newline character, and a backslash
             followed by the delimiting character is replaced by that
             character, causing it to be treated literally, with the exception
             of the `n' character, which will still be treated like a newline
             character.  It is an error for a backslash to not be followed by
             another backslash, `n', or the delimiting character, or for
             string1 to contain repeating characters.

             This function does nothing; it bears a label to which the b and t
             commands may branch.

             Write the line number to the standard output followed by a
             newline character.

             Empty lines are ignored.

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


     COLUMNS  If set to a positive integer, output from the l function is
              formatted to the given width in columns.  Otherwise, sed
              defaults to the terminal width, or 80 columns if the output is
              not a terminal.


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


     awk(1), ed(1), grep(1), re_format(7)


     The sed utility is compliant with the IEEE Std 1003.1-2008 ("POSIX.1")

     The flags [-aEiru] 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.


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


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

OpenBSD 6.4                      July 11, 2018                     OpenBSD 6.4

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