What does the 'grep' command do in Linux?

The 'grep' command in Linux is specifically designed to search for text or specific patterns within files. Its name stands for "Global Regular Expression Print," and it utilizes regular expressions to match patterns against the content of files. When you execute a grep command, it scans the input (which can be one or more files, or even standard input) and prints lines that contain a match to the specified pattern. This functionality is extremely useful for administrators and users alike when they need to filter through large volumes of text, logs, or code to find specific information quickly and efficiently.

In contrast, the other choices pertain to different actions in Linux. Listing files is typically done with commands like 'ls,' changing file permissions is achieved using 'chmod,' and copying files is done using 'cp.' Each of these commands serves distinct purposes, emphasizing the specialized role that 'grep' plays in text pattern searching.