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Regular Expressions
GREP searches the named input files (or standard input if no
files are named, or the file name `-
' is given) for lines containing
a match to the given pattern. By default, GREP prints the matching lines.
There are three major variants of GREP, controlled by the following options.
`-G '
` --basic-regexp '
|
Interpret pattern as a basic regular expression. This is the default. |
`-E '
| |
`--extended-regexp '
|
Interpret pattern as an extended regular expression. |
`-F '
` --fixed-strings '
|
Interpret pattern as a list of fixed strings, separated by newlines, any of which is to be matched. |
In addition, two variant programs EGREP and FGREP are available.
EGREP is similar (but not identical) to `grep -E
', and
is compatible with the historical Unix EGREP. FGREP is the
same as `grep -F
'.