File: sed.info,  Node: Command-Line Options,  Next: Exit status,  Prev: Overview,  Up: Invoking sed

2.2 Command-Line Options
========================

The full format for invoking ‘sed’ is:

     sed OPTIONS... [SCRIPT] [INPUTFILE...]

   ‘sed’ may be invoked with the following command-line options:

‘--version’
     Print out the version of ‘sed’ that is being run and a copyright
     notice, then exit.

‘--help’
     Print a usage message briefly summarizing these command-line
     options and the bug-reporting address, then exit.

‘-n’
‘--quiet’
‘--silent’
     By default, ‘sed’ prints out the pattern space at the end of each
     cycle through the script (*note How ‘sed’ works: Execution Cycle.).
     These options disable this automatic printing, and ‘sed’ only
     produces output when explicitly told to via the ‘p’ command.

‘--debug’
     Print the input sed program in canonical form, and annotate program
     execution.
          $ echo 1 | sed '\%1%s21232'
          3

          $ echo 1 | sed --debug '\%1%s21232'
          SED PROGRAM:
            /1/ s/1/3/
          INPUT:   'STDIN' line 1
          PATTERN: 1
          COMMAND: /1/ s/1/3/
          PATTERN: 3
          END-OF-CYCLE:
          3

‘-e SCRIPT’
‘--expression=SCRIPT’
     Add the commands in SCRIPT to the set of commands to be run while
     processing the input.

‘-f SCRIPT-FILE’
‘--file=SCRIPT-FILE’
     Add the commands contained in the file SCRIPT-FILE to the set of
     commands to be run while processing the input.

‘-i[SUFFIX]’
‘--in-place[=SUFFIX]’
     This option specifies that files are to be edited in-place.  GNU
     ‘sed’ does this by creating a temporary file and sending output to
     this file rather than to the standard output.(1).

     This option implies ‘-s’.

     When the end of the file is reached, the temporary file is renamed
     to the output file's original name.  The extension, if supplied, is
     used to modify the name of the old file before renaming the
     temporary file, thereby making a backup copy(2)).

     This rule is followed: if the extension doesn't contain a ‘*’, then
     it is appended to the end of the current filename as a suffix; if
     the extension does contain one or more ‘*’ characters, then _each_
     asterisk is replaced with the current filename.  This allows you to
     add a prefix to the backup file, instead of (or in addition to) a
     suffix, or even to place backup copies of the original files into
     another directory (provided the directory already exists).

     If no extension is supplied, the original file is overwritten
     without making a backup.

     Because ‘-i’ takes an optional argument, it should not be followed
     by other short options:
     ‘sed -Ei '...' FILE’
          Same as ‘-E -i’ with no backup suffix - ‘FILE’ will be edited
          in-place without creating a backup.

     ‘sed -iE '...' FILE’
          This is equivalent to ‘--in-place=E’, creating ‘FILEE’ as
          backup of ‘FILE’

     Be cautious of using ‘-n’ with ‘-i’: the former disables automatic
     printing of lines and the latter changes the file in-place without
     a backup.  Used carelessly (and without an explicit ‘p’ command),
     the output file will be empty:
          # WRONG USAGE: 'FILE' will be truncated.
          sed -ni 's/foo/bar/' FILE

‘-l N’
‘--line-length=N’
     Specify the default line-wrap length for the ‘l’ command.  A length
     of 0 (zero) means to never wrap long lines.  If not specified, it
     is taken to be 70.

‘--posix’
     GNU ‘sed’ includes several extensions to POSIX sed.  In order to
     simplify writing portable scripts, this option disables all the
     extensions that this manual documents, including additional
     commands.  Most of the extensions accept ‘sed’ programs that are
     outside the syntax mandated by POSIX, but some of them (such as the
     behavior of the ‘N’ command described in *note Reporting Bugs::)
     actually violate the standard.  If you want to disable only the
     latter kind of extension, you can set the ‘POSIXLY_CORRECT’
     variable to a non-empty value.

‘-b’
‘--binary’
     This option is available on every platform, but is only effective
     where the operating system makes a distinction between text files
     and binary files.  When such a distinction is made--as is the case
     for MS-DOS, Windows, Cygwin--text files are composed of lines
     separated by a carriage return _and_ a line feed character, and
     ‘sed’ does not see the ending CR. When this option is specified,
     ‘sed’ will open input files in binary mode, thus not requesting
     this special processing and considering lines to end at a line
     feed.

‘--follow-symlinks’
     This option is available only on platforms that support symbolic
     links and has an effect only if option ‘-i’ is specified.  In this
     case, if the file that is specified on the command line is a
     symbolic link, ‘sed’ will follow the link and edit the ultimate
     destination of the link.  The default behavior is to break the
     symbolic link, so that the link destination will not be modified.

‘-E’
‘-r’
‘--regexp-extended’
     Use extended regular expressions rather than basic regular
     expressions.  Extended regexps are those that ‘egrep’ accepts; they
     can be clearer because they usually have fewer backslashes.
     Historically this was a GNU extension, but the ‘-E’ extension has
     since been added to the POSIX standard
     (http://austingroupbugs.net/view.php?id=528), so use ‘-E’ for
     portability.  GNU sed has accepted ‘-E’ as an undocumented option
     for years, and *BSD seds have accepted ‘-E’ for years as well, but
     scripts that use ‘-E’ might not port to other older systems.  *Note
     Extended regular expressions: ERE syntax.

‘-s’
‘--separate’
     By default, ‘sed’ will consider the files specified on the command
     line as a single continuous long stream.  This GNU ‘sed’ extension
     allows the user to consider them as separate files: range addresses
     (such as ‘/abc/,/def/’) are not allowed to span several files, line
     numbers are relative to the start of each file, ‘$’ refers to the
     last line of each file, and files invoked from the ‘R’ commands are
     rewound at the start of each file.

‘--sandbox’
     In sandbox mode, ‘e/w/r’ commands are rejected - programs
     containing them will be aborted without being run.  Sandbox mode
     ensures ‘sed’ operates only on the input files designated on the
     command line, and cannot run external programs.

‘-u’
‘--unbuffered’
     Buffer both input and output as minimally as practical.  (This is
     particularly useful if the input is coming from the likes of ‘tail
     -f’, and you wish to see the transformed output as soon as
     possible.)

‘-z’
‘--null-data’
‘--zero-terminated’
     Treat the input as a set of lines, each terminated by a zero byte
     (the ASCII ‘NUL’ character) instead of a newline.  This option can
     be used with commands like ‘sort -z’ and ‘find -print0’ to process
     arbitrary file names.

   If no ‘-e’, ‘-f’, ‘--expression’, or ‘--file’ options are given on
the command-line, then the first non-option argument on the command line
is taken to be the SCRIPT to be executed.

   If any command-line parameters remain after processing the above,
these parameters are interpreted as the names of input files to be
processed.  A file name of ‘-’ refers to the standard input stream.  The
standard input will be processed if no file names are specified.

   ---------- Footnotes ----------

   (1) This applies to commands such as ‘=’, ‘a’, ‘c’, ‘i’, ‘l’, ‘p’.
You can still write to the standard output by using the ‘w’ or ‘W’
commands together with the ‘/dev/stdout’ special file

   (2) Note that GNU ‘sed’ creates the backup file whether or not any
output is actually changed.