Shell script regex to check for a string

Question

I'm trying to write a simple regex in a shell script and I can't get it to match anything. I'm not sure if my regex is incorrect or my shell code is incorrect

#!/bin/sh
#
# This hook verifies that the commit message contains a reference to a tfs item

# Regex to validate a string contains "#" and 4 or 5 digits
regex="/#\d{4,5}/"
param=$1
echo "param = $param"
echo "regex = $regex"

if [[ $param =~ $regex ]]; then
  output="yes"
else
  output="no"
fi

echo "output = $output"

...

I'm running my script with $ ./myscript "#1234" and $ ./myscript "asdf #1234 asdf" and those should both output "yes"

anubhava · Accepted Answer · 2015-04-09 17:34:06Z

2

regex="/#\d{4,5}/"

Is not correct regex for BASH. You can use:

regex="#[0-9]{4,5}"

No regex delimiters in BASH regex
\d, \w properties are not supported

answered Apr 9, 2015 at 17:34

anubhava

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10 Comments

Catfish Over a year ago

This doesn't quite work. It also also passes with $ ./myscript "asdf "#123456789"...which means my regex is not quite right.

tripleee Over a year ago

You need to add a $ at the end to anchor the match if that's what you want. A regex will match anywhere in a longer string unless you anchor it.

Catfish Over a year ago

@tripleee if I add a $ at the end that makes it so $ ./myscript "asdf #1234 asdf" doesn't work. I basically want to allow a hashtag followed by 4 or 5 digits anywhere in the string.

tripleee Over a year ago

So it can be followed by anything as long as it's not a number? Then "#[0-9]{4,5}($|[^0-9])"

Catfish Over a year ago

It could be followed by a number again. So this would be allowed asdf #1234 1 also. I just want to require that hashtag followed by 4 or 5 digits exists anywhere in the string.

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