Bash Script Regular Expression Issue

Question

I've got the following code and have looked at numerous examples but cannot figure out what I'm doing wrong. I know the regular expression works (see https://regex101.com/r/cB9hN1/1) - just not in my bash script. It's for a git update hook, but clearly I'm doing something wrong! Here's what I've got:

regex='ref:( |)([D]|[U])([E]|[S])(\d+)';
string="My commit ref: US2233556"

if [[ $string =~ $regex ]];
  then
    echo "[SUCCESS] Your message contains ref: for a Story or Defect."
    exit 0
else
    echo "[POLICY] Your message is not formatted correctly. Please include a \"ref: USXXXXX\" or \"ref: DEXXX\" in the commit message."
    exit 1
fi

I'd appreciate any help! Thank you!

Use regex='ref:( |)([DU])([ES])([0-9]+)';.

Wiktor Stribiżew
– Wiktor Stribiżew

2015-10-21 15:39:08 +00:00
Commented Oct 21, 2015 at 15:39 — Wiktor Stribiżew
– Wiktor Stribiżew, Commented Oct 21, 2015 at 15:39

Wiktor Stribiżew · Accepted Answer · 2015-10-21 15:46:30Z

1

You should use [0-9] instead of \d and you can merge alternated character classes into single classes ([D]|[U] = [DU]):

regex='ref:( |)([DU])([ES])([0-9]+)';

See demo here

If you are not using capture groups, just remove them:

regex='ref: ?[DU][ES][0-9]+';

Here is another demo. Note that ( |) can be written shorter as ( ?) or ( )? and this way it will cause less backtracking.

edited Oct 21, 2015 at 15:46

answered Oct 21, 2015 at 15:41

Wiktor Stribiżew

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3 Comments

Meezaan-ud-Din Over a year ago

Seriously, that \d+ was my main problem?!

Wiktor Stribiżew Over a year ago

Yes, it was the main problem. Bash does not support the PCRE regex flavor, it is much poorer.

Meezaan-ud-Din Over a year ago

Oh dear! Thank you! Will accept the answer as soon as I'm allowed to!

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