Manipulating strings with sed

The sed program performs its editing without interacting with the person requesting the editing.

This method of operation allows sed to do the following:

• Edit very large files
• Perform complex editing operations many times without requiring extensive retyping and cursor positioning (as interactive editors do)
• Perform global changes in one pass through the input.

The editor keeps only a few lines of the file being edited in memory at one time, and does not use temporary files. Therefore, the file to be edited can be any size as long as there is room for both the input file and the output file in the file system.