GNU sed accepts a number of additional command-line options, as well as long-option equivalents for the standard options. The GNU sed options are:
Use cmd as editing commands.
Obtain editing commands from file.
Print a usage message and exit.
Edit files in place, overwriting the original file. If optional suffix is supplied, use it for renaming the original file as a backup file. See the GNU sed online Info documentation for the details.
Set the line length for the l command to len characters.
Suppress the default output; sed displays only those lines specified with the p command or with the p flag of the s command.
Disable all GNU extensions. Setting POSIXLY_CORRECT in the environment merely disables those extensions that are incompatible with the POSIX standard.
Use Extended Regular Expressions instead of Basic Regular Expressions. See Chapter 7 for more information.
Instead of considering the input to be one long stream consisting of the concatenation of all the input files, treat each file separately. Line numbers start over with each file, the address $ refers to the last line of each file, files read by the R command are rewound, and range addresses (/x/,/y/) may not cross file boundaries.
Buffer input and output as little as possible. Useful for editing the output of tail -f when you ...