A Practical Guide to LinuxR Commands, Editors, and Shell Programming

The program is a sed program that is included on the command line. This format allows you to write simple, short sed programs without creating a separate program-file. The program-file is the pathname of a file containing a sed program (see "Editor Basics"). The file-list contains pathnames of the ordinary files that sed processes. These are the input files. When you do not specify a file, sed takes its input from standard input.