The grep Command
The grep command is so beloved by Linux users that it has its own t-shirts. The grep command finds files that have specified contents and outputs each line that it finds. The general format for the grep command is:
grep options pattern files
where:
pattern specifies the text string to search for. pattern can be a literal string, such as abc or xxx. pattern can also be a regular expression, a pattern to be matched, such as any uppercase character or any word that begins with Q. Regular expressions are discussed in Appendix A.
files specifies the files to search for the string. files can specify filenames (using wildcards if needed) or a directory.
For example, the following is a simple grep command with its output:
grep "Mary ...
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