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sed, a stream editor

2. Invocation

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

-V

--version

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

-h

--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. These options disable this automatic printing, and sed only produces output when explicitly told to via the p command.

-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)

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)) following this rule: 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).

This option implies `-s'.

-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.

-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 less backslashes, but are a GNU extension and hence scripts that use them are not portable. See section Extended regular expressions.

-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.

-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.)

-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.

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.