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;

[Recommended reading on Regular Expressions in Bash](http://mywiki.wooledge.org/BashGuide/Patterns#Regular_Expressions-1) — Tom Fenech, Feb 18 '15 at 10:26
Regarding your latest deleted question. As you deleted it, I was typing an answer based on one of my [previous answers](http://stackoverflow.com/questions/10894692/python-outfile-to-another-text-file-if-exceed-certain-file-size); perhaps it will help — Mike Pennington, Feb 22 '15 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, Feb 22 '15 at 13:15

score 2 · Answer 1 · answered Feb 18 '15 at 10:21

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

1 Answers1