bash if [[ =~ regex compare not working?

Question

I have a value in a variable that may be absolute or relative url, and I need to check which one it is.

I have found that there's a =~ operator in [[, but I can't get it to work. What am I doing wrong?

url="http://test"
if [[ "$url" =~ "^http://" ]];
    then echo "absolute.";
fi;

Regarding your latest deleted question. As you deleted it, I was typing an answer based on one of my previous answers; perhaps it will help — Mike Pennington
– Mike Pennington, Commented Feb 22, 2015 at 13:11
@MikePennington I just wanted to avoid any more downvotes, after I found out that global is not needed there at all, it was all clear. — MightyPork
– MightyPork, Commented Feb 22, 2015 at 13:15

anubhava · Accepted Answer · 2015-02-18 10:21:48Z

2

You need to use regex without quote:

url="http://test"
if [[ "$url" =~ ^http:// ]]; then
    echo "absolute."
fi

This outputs `absolute. as regex needs to be without quote in newer BASH (after BASH v3.1)

Or avoid regex and use glob matching:

if [[ "$url" == "http://"* ]]; then
    echo "absolute."
fi

answered Feb 18, 2015 at 10:21

anubhava

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