BASH regex check not matching on linux

Question

I have been scripting something in BASH and I have found a strange bug. I have been developing on Mac (El Capitan) and everything is working flawlessly. But deployment on Ubuntu 16.06 server is failing and I have no idea why.

My code follows

while ! [[ ${someVariable} =~ ^[a-zA-z0-9_-]{40}$ ]]
do
    read someVariable
    if ! [[ ${someVariable} =~ ^[a-zA-z0-9_-]{40}$ ]];then  
        echo 'try again'
    fi
done

for input 6LfMYB8TAAAAACRZ9bP-0GN9y4zKUYPtj255-e8A this fails. And failure happens on server only and not on the development machine. I have a feeling that I have missed something obvious.

What @James says. But also, possible different versions of bash (bash --version)? — Jeff Y
– Jeff Y, Commented Jun 23, 2016 at 20:09
A deleted answer mentions the suspicious-looking range A-z. Please confirm that your script continues to fail if you replace that with A-Z. — chepner
– chepner, Commented Jun 23, 2016 at 20:45
The range was bad, it was a simple typo. Lucky for me was that i copied the whole if. If I had typed it again here I would have not make the same mistake — Rouz
– Rouz, Commented Jun 23, 2016 at 20:58

OkieOth · Accepted Answer · 2016-06-23 20:37:22Z

2

There is a typo in your ranges. The upper case range must be from A-Z This code works on Ubuntu 14.04

while ! [[ ${someVariable} =~ ^[a-zA-Z0-9_-]{40}$ ]]
do
    read someVariable
    if ! [[ ${someVariable} =~ ^[a-zA-Z0-9_-]{40}$ ]];then  
        echo 'try again'
    fi
done

edited Jun 23, 2016 at 20:37

answered Jun 23, 2016 at 20:14

OkieOth

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2 Comments

that other guy Over a year ago

This. The reason why OP is seeing differing results for A-z is due to the locale. It would accidentally work for LC_COLLATE=C (the default) and POSIX, but would fail for systems using e.g. en_US.utf8.

Rouz Over a year ago

yes! the problem was caused by simple typo... I feel silly sometimes. Thank you!

James · Accepted Answer · 2016-06-23 20:03:48Z

1

try this regex?

^[-_a-zA-Z0-9]{40}$

answered Jun 23, 2016 at 20:03

James

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2 Comments

Rouz Over a year ago

Although my problem was due to simple typo I have failed to see (range was A-z instead A-Z) I would like to know why would this regex be better and, of course, why would you suggest this solution. Is this more efficient or...?

James Over a year ago

oh i just typed out what I thought would work into a terminal. I figured you would do the diff and figure out what went wrong.

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