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? — Charles Duffy
– Charles Duffy, Commented Jul 28, 2013 at 14:28

user2627497 · Accepted Answer · 2013-07-28 11:53:18Z

4

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

answered Jul 28, 2013 at 11:53

user2627497

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Comments

cmbuckley · Accepted Answer · 2013-07-29 10:54:56Z

4

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

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

cmbuckley

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answered Jul 28, 2013 at 11:46

Peter Butkovic

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You'll need to escape the ., otherwise it will match 2c2 and the like.

correct, I had it in my post, just seems like it was rendered without it, thanks for remark, updated my solution