Grep

2007-07-29T18:20:41Z

89.180.206.215: /* Examples */

The [[grep]] command serves in shell scripting and in OS command lines to filter out relevant ASCII data from standard input. It's best used in conjunction with [http://en.wikipedia.org/wiki/Pipe_(Unix) pipes].

==Regexps==
The dot '.' is a basic wildcard that will stand for any character. For example
> ll | grep d.t
will list all lines containing dat, ''dut'', ''dit'', ''dot'', etc...
The following will look for any line containing ''hello.gif'':
> ll | grep 'hello\.gif'

==Examples==
For example, the following command will only display the files containing a ''.dat'' extension.
> ls -l | grep .dat
Here's the same example for dos (windows)
> dir /B | grep .dat

The following example lists only directories (i.e. everything but lines ending with '.????' or '.???' or '.??')

in dos
$ dir /B /S | grep "[^.]....$" | grep "[^.]...$" | grep "[^.]..$"
in linux
> find . | grep '[^.]....$' | grep '[^.]...$' | grep '[^.]..$'

Here's another example that lists every hdf5 file except the ''Interface'''S'''edimentWater''
> find . | grep '.hdf5$' | grep '^...........[^S]'

Here's an example that lists everything except the pattern
> find .| grep '\.f90' | grep -v 'GOTMvariables'

This example will show only the crond daemon

> ps -aux | grep crond

==External References==
*[http://en.wikipedia.org/wiki/Grep Grep in WikiPedia.]
*[http://gnuwin32.sourceforge.net/packages/grep.htm Grep for windows.]
*[http://pegasus.rutgers.edu/~elflord/unix/grep.html Tutorial.]
[[Category:Tools]]
[[Category:Linux]]
[[Category:Technology]]

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Grep