Getting a number out of a string in bash

Luc484 · 01-19-2006, 01:31 AM

Hi. I have the output of a command with grep which is string with a number inside. Is it possible to get that number somehow? For instance, I have this string:

Code:

Pages:         n

where n is an integer. Is it possible to get the n and to put it into another variable to use it with some arithmetic operators?
Thanks.

kshkid · 01-19-2006, 08:24 AM

from your requirement

Code:

echo "Pages:    10" | sed 's/[^0-9]//g'

suppress everything except digits from 0-9.

and in a variable

Code:

var=`echo "Pages:    10" | sed 's/[^0-9]//g'`
echo $var

Hope this helps.

Hko · 01-19-2006, 11:07 AM

...and after that you can use the number $var (still being a string, as everything in bash scripts is a string) like thisin arithmics:

Code:

# ...
var2=$(($var + 1))
echo$var2

Luc484 · 01-19-2006, 04:59 PM

Great, exactly what I needed. Thanks.

chrism01 · 01-19-2006, 11:14 PM

Alternatively, you could use:
awk '{print $2}'
instead of the sed stuff; just another option. Personally I find it easier to read.

kshkid · 01-20-2006, 02:15 AM

one more alternative with sed,

Code:

echo "Pages:    10" | sed 's/.* //g'