Difference between revisions of "Grep"
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| + | grep is a [[command]] that reads strings and only outputs them if they ''match'' a ''pattern''. For example to show all lines in a file ''syslog'' that contain the string ''Nov'' call it like: | ||
| + | grep "''Nov''" ''syslog'' | ||
| + | |||
| + | <iframe width="90%" height="600" allowfullscreen frameborder="0" src="https://bubbl.us/NTcxNTA0MC8xMzA2MDQ3Ny82MDgyNzQ0ODUyYjUyZGQyN2ZlNmUyZjcyMzQ0ZDJlZg==-X?s=13060477&utm_source=page-embed&utm_medium=link"></iframe> | ||
| + | |||
| + | = Examples = | ||
* Show all lines that do '''not''' contain blabla | * Show all lines that do '''not''' contain blabla | ||
grep -v blabla filename.txt | grep -v blabla filename.txt | ||
| Line 14: | Line 20: | ||
* Match any character but blank | * Match any character but blank | ||
grep -E "L[^ ]nux" | grep -E "L[^ ]nux" | ||
| − | + | Matches Linux, Lanux, but not Lnux and not L nux | |
| + | |||
| + | * Match any line starting with a character | ||
| + | grep -E "U" | ||
| + | Matches all lines starting with U | ||
| + | |||
| + | * Show all files containing ''content'' | ||
| + | grep -ir "''content''" * | ||
| + | |||
| + | = Usecases = | ||
| + | |||
| + | == Show all running processes == | ||
| + | |||
| + | [[ps]] auxf | grep -E "^[^ ]+ +[^ ]+ +[^ ]+ +[^ ]+ +[^ ]+ +[^ ]+ +[^ ]+ +R" | ||
= See also = | = See also = | ||
* [[regex]] | * [[regex]] | ||
| + | |||
| + | [[Category:Command]] | ||
Latest revision as of 17:57, 28 February 2022
grep is a command that reads strings and only outputs them if they match a pattern. For example to show all lines in a file syslog that contain the string Nov call it like:
grep "Nov" syslog
<iframe width="90%" height="600" allowfullscreen frameborder="0" src="https://bubbl.us/NTcxNTA0MC8xMzA2MDQ3Ny82MDgyNzQ0ODUyYjUyZGQyN2ZlNmUyZjcyMzQ0ZDJlZg==-X?s=13060477&utm_source=page-embed&utm_medium=link"></iframe>
Examples
- Show all lines that do not contain blabla
grep -v blabla filename.txt
- Match any character
With a dot (.) you can match any character
grep -E "L.nux"
Matches Linux, Lanux L nux, but not Lnux
- Match all characters
With a .* you can match an arbitrary count of any character
grep -E "L.*nux"
Matches Linux, Liinux, Lanux, L nux and Lnux
- Match any character but blank
grep -E "L[^ ]nux"
Matches Linux, Lanux, but not Lnux and not L nux
- Match any line starting with a character
grep -E "U"
Matches all lines starting with U
- Show all files containing content
grep -ir "content" *
Usecases
Show all running processes
ps auxf | grep -E "^[^ ]+ +[^ ]+ +[^ ]+ +[^ ]+ +[^ ]+ +[^ ]+ +[^ ]+ +R"
