bash -- how to judge if a variable is a string or number

Question

In bash shell, how do we judge if a variable is a string or number? Here, number could be an integer or a float. This link "How to judge a variable's type as string or integer" seems to only work integer.

possible duplicate of [How do I test if a variable is a number in bash?](http://stackoverflow.com/questions/806906/how-do-i-test-if-a-variable-is-a-number-in-bash) — Charles Duffy, Jul 28 '13 at 14:28

score 4 · Answer 1 · edited Jul 29 '13 at 10:54

4

Based on referred question, following does the job for me:

[[ $value =~ ^[0-9]+(\.[0-9]+)?$ ]]

edited Jul 29 '13 at 10:54

cmbuckley

answered Jul 28 '13 at 11:46

Peter Butkovic

1

You'll need to escape the `.`, otherwise it will match `2c2` and the like. – cmbuckley Jul 28 '13 at 11:50
correct, I had it in my post, just seems like it was rendered without it, thanks for remark, updated my solution – Peter Butkovic Jul 28 '13 at 11:55

score 4 · Accepted Answer · answered Jul 28 '13 at 11:53

You could expand the proposed regular expression, dependent on the desired number format(s):

[[ $value =~ ^[0-9]+(\.[0-9]+)?$ ]] would recognize 2 or 2.4 as a number but 2. or .4 as a string.

[[ $value =~ ^(\.[0-9]+|[0-9]+(\.[0-9]*)?)$ ]] would recognize all 2, 2.4, 2. and .4 as numbers

2 Answers2