Explantation: The sed(Stream Editor) command is commonly used for text replacement in files. -i- Edits the file in place (modifies /etc/app.cfgdirectly). s/old/new/g- Replaces all occurrences (g= globally) of 10.115.6.5with 10.116.6.5. /etc/app.cfg- Specifies the file to modify.