Invoking (GNU Grep 3.7)
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2 Invoking grep
The general synopsis of the grep command line is
grep [option...] [patterns] [file...]
There can be zero or more option arguments, and zero or more file arguments. The patterns argument contains one or more patterns separated by newlines, and is omitted when patterns are given via the ‘-e patterns’ or ‘-f file’ options. Typically patterns should be quoted when grep is used in a shell command.