grep a file, but show several surrounding lines?
I would like to
grep for a string, but also show the preceding five lines and the following five lines as well as the matched line. How would I be able to do this?
For BSD or GNU
grep you can use
-B num to set how many lines before the match and
-A num for the number of lines after the match.
grep -B 3 -A 2 foo README.txt
If you want the same number of lines before and after you can use
grep -C 3 foo README.txt
This will show 3 lines before and 3 lines after.
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-B will work, as will
-C n (for
n lines of context), or just
n lines of context... as long as n is 1 to 9).
grep astring myfile -A 5 -B 5
That will grep "myfile" for "astring", and show 5 lines before and after each match
I normally use
grep searchstring file -C n # n for number of lines of context up and down
Many of the tools like grep also have really great man files too. I find myself referring to grep's man page a lot because there is so much you can do with it.
Many GNU tools also have an info page that may have more useful information in addition to the man page.
$ grep --help | grep -i context Context control: -B, --before-context=NUM print NUM lines of leading context -A, --after-context=NUM print NUM lines of trailing context -C, --context=NUM print NUM lines of output context -NUM same as --context=NUM