The grep command makes it easy to find strings in text files on Linux systems, but that’s just a start. It can be used to search through these files for multiple strings or regular expressions at the same time. It can also ignore case when needed, and it can count the lines in the resulting output for you. This post shows how to use grep in all these ways.
Basic grep
The simplest grep command looks like the one shown below. This “find string in file” command will show all the lines in the file that contain the string, even when that string is only part of a longer one.
