grep (global regular expression processor) is a utility program that searches a file, or files, for lines that contain a particular string pattern. Unlike the find command, which searches directory structures for files that meet certain criteria, grep searches files for lines that contain a particular pattern.
We can use grep to search for a simple fixed character string, or it can be used to search for more complex patterns called “regular expressions.” First let’s take a look at the command syntax, and then I’ll describe how to use grep to search for simple strings.
The command syntax for the grep command is as follows:
grep <-options> search-pattern files-to-search
Some of the more common options to the grep command are described ...