Bash parameter expansion works only in interactive shell, but not in script

Question

In user's console I have bash:

$ echo $SHELL
/bin/bash
$ bash --version
GNU bash, version 4.2.46(1)-release (x86_64-redhat-linux-gnu)

I have code in file test.sh:

$ cat test.sh
aaa='---aa-aa---'
echo "${aaa}"
echo 'does not work...'
# trim "-"
echo ${aaa/+(-)}
echo ${aaa%%+(-)}
echo 'works for one symbol...'
echo ${aaa%-}
echo ${aaa/-}

The last two rows work fine but previous ones.

$ bash test.sh
---aa-aa---
does not work...
---aa-aa---
---aa-aa---
works for one symbol...
---aa-aa--
--aa-aa---

In the same time, if you would try to make this console it works:

$ aaa='---aa-aa---'
$ echo ${aaa/+(-)}
aa-aa---
$ echo ${aaa%%+(-)}
---aa-aa

So, why it doesn't work in a script?

Trying to decide whether to close this as a duplicate of stackoverflow.com/questions/26726264/…, or do it the other way 'round. @tripleee, do you have an opinion here? — Charles Duffy
– Charles Duffy, Commented Oct 21, 2016 at 16:04
...actually, on review, I think this instance of the question is more clearly asked than the other, enough to negate the other's temporal advantage (from being asked first).. — Charles Duffy
– Charles Duffy, Commented Oct 21, 2016 at 16:06

tripleee · Accepted Answer · 2016-10-21 15:30:02Z

5

You seem to have shopt -s extglob enabled in your interactive shell, which turns on extended globbing. This is not the default behavior, and needs to be explicitly enabled in your script. See extended pattern matching in the bash hackers wiki for details.

edited Oct 21, 2016 at 15:30

answered Oct 21, 2016 at 15:25

tripleee

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1 Comment

chepner Over a year ago

Without shopt -s extglob, the pattern +(-) is a literal 4-character string to match, not a pattern matching one or more -.

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