sed

sed(Stream Editor) command in UNIX can perform lots of functions on file like searching, finding and replacing, insertion or deletion. By using SED you can edit files even without opening them in editors like VI Editor.

It has the following syntax:

$ sed [options].. [script] [input-file] e.g. $ sed 's/search-regex/replacement-txt/g' file.txt

Visit the following resources to learn more:

• What is SED? with examples
• Detailed Manual
• Linux Crash Course - The sed Command