What does the 'grep' command do?

The 'grep' command is a powerful text searching utility in Linux and Unix-like operating systems. It is specifically designed to search for specific patterns within files or standard input. When you use 'grep', you can specify a pattern (which can be a simple string or a more complex regular expression) that the command will look for in the provided input files. If the pattern is found, 'grep' will output the lines from those files that contain the matching pattern.

This functionality makes 'grep' particularly useful for tasks such as analyzing log files, searching source code for occurrences of a specific function or variable, or filtering output from other commands. Its versatility and efficiency in searching through large amounts of text data have made it an essential tool for system administrators and developers alike.