use of grep -m NUM

rajsierra · 11-23-2011, 01:31 AM

I know its a very simple question, but can you help me on using the -m option with grep to display the content of file once it reach NUM

neonsignal · 11-23-2011, 01:49 AM

The '-m' option just sets a maximum number of matches; if grep reaches that number of matches, then it will stop.

If you do it within a script, then the rest of the standard input will not be consumed; this means that you can continue on searching later in the script. For example, you could have a script which looped around, doing 'grep -m1' each time, until it got to the end of the input.

rajsierra · 11-23-2011, 02:37 AM

thanks neon, ok let me give one scenario, I've a file in which I've set of numbers, I want to display the numbers only till 10, how can I run the command if I'm saying cat <filename>| grep m5, it should display me all the values less then 5, correct..? but it is not, I know I'm not using it correct, can you let me know how should I use it.

neonsignal · 11-23-2011, 02:43 AM

The '-m' flag does not control the pattern being matched, it only controls how many matches happen before exiting. You still have to specify a pattern to match.

For example, if your file input.txt contained:

Code:

a
b
aaa
bbb
aa
bb

and you said

Code:

grep -m2 'a' <input.txt

then the grep will match all the lines with the character 'a', but the '-m2' will stop it after the first two matches. So the output will be:

Code:

a
aaa

rajsierra · 11-23-2011, 04:11 AM

oh okey got it, now is there any thing using grep or sort I can display the values from a file which is less then some n mumber
like I have a file numbers.txt, which contains number
4
8
10
15
3
2

so I want to display the output where number is less then 10 and the result will be

4
8
3
2

colucix · 11-23-2011, 04:52 AM

Try awk:

Code:

awk '$1 < 10' file