bash operator if statement is not a number [duplicate]

Question

I want to exclude everything which is not a number coming from my variable:

Example:

good variable: 4564 or 332 or 1

bad variable: er0rr or E131 or KE1

I'm not sure how to make if statement to recognize that the output is a number.

anubhava · Accepted Answer · 2015-02-13 15:34:08Z

1

In BASH you can use this regex condition to check if variable n contains only digits:

[[ "$n" =~ ^[[:digit:]]+$ ]]

answered Feb 13, 2015 at 15:34

anubhava

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1 Comment

gniourf_gniourf Over a year ago

Or this extended glob pattern: [[ $n = +([[:digit:]]) ]]. Note that this doesn't guarantee that you'll be able to use this number in Bash's arithmetic context. For example, n=09 passes this test, yet will raise an 09: value too great for base (error token is "09") error when used in arithmetic context. To fix this, you'll use, after this test, the following: n=$((10#$n)).

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