using grep help

saiz66 · 02-03-2005, 09:41 PM

How do I get grep to return to me the lines that ONLY contain digits? Thanks!

homey · 02-03-2005, 09:52 PM

Try this...
grep -o "[0-9]*"

saiz66 · 02-03-2005, 09:57 PM

thanks but i have a file with a line of 12abc and I am supposed to only get the lines which have ONLY digits which in that case i shouldnt receive anything back from grep.. but when I run your code I get 12... which is not what I want..

jtshaw · 02-03-2005, 09:58 PM

You'd want to use the regular expression syntax for that.

Something like: grep --regex="[1-9*]" <file>

There are a bunch of sites that will give you indepth information on regular expressions.

The Regular Expression Tutorial and this Regular Expression How-To might be helpful, though neither deals specifically with grep.

chrism01 · 02-03-2005, 10:50 PM

This is along the right lines...
grep [0-9] file|grep -v [a-zA-z]

I'm assuming this isn't a homework qn?
http://www.catb.org/~esr/faqs/smart-....html#homework

jtshaw · 02-03-2005, 10:56 PM

Ya, sorry, I was refreshing my grep usage before I posted and didn't notice that somebody had already posted the same thing... and that you had already said it wasn't quite what you were looking for