Replacing the =~ operator check in the if statement

Question

I have the following check:

if [[ "$abc" =~ ^((git|ssh|http(s)?)|(git@[\w\.]+))(:(\/\/)?)([A-Za-z0-9.@:_/-]+)\.com(:[0-9]+)?\/([A-Za-z0-9.@:_/-]+)\/([a-zA-Z0-9_]+)(\.git)(\/)?$ ]]; then
   die "Invalid"
fi

It does not really matter what it checks, I just want to get rid of the =~ operator. I have a basic static test of the scripts:

for file in $filelist
do
  echo -n "Checking $file..."
  bash -n $file
  echo "OK"
done

Due to the =~ operator, it gets an error:

syntax error in conditional expression: unexpected token `('
script: line 847: syntax error near `^(('

Even though, when I execute the script itself, I don't get that error. I guess the error is due to not wrapping ^((git|ssh|http(s)?)|(git@[\w\.]+))(:(\/\/)?)([A-Za-z0-9.@:_/-]+)\.com(:[0-9]+)?\/([A-Za-z0-9.@:_/-]+)\/([a-zA-Z0-9_]+)(\.git)(\/)?$ with apostrophes. If I do wrap it, it will not enter the if statement. So I'm looking to replace the =~. What is the proper way to do so?

I'm unable to reproduce this. I put your check in a file foo and ran bash -n foo and it completed without errors. — that other guy
– that other guy, Commented Dec 20, 2019 at 23:53
@thatotherguy Sorry, I thought it was a problem with =~ and not a problem with the regex itself. I updated the full regex. It a problem with the regex? — vesii
– vesii, Commented Dec 20, 2019 at 23:55
I'm unable to reproduce the problem with this new regex as well. — that other guy
– that other guy, Commented Dec 20, 2019 at 23:58
@thatotherguy I'm not sure why but I get this behavior. Is it possible to use that regex with the apostrophes? — vesii
– vesii, Commented Dec 20, 2019 at 23:59
Can you please try it with just your 3 line check and your 6 line test loop? I.e. keep your existing 850+ line scripts out of it and just use what you've posted to ensure that the post contains all relevant information — that other guy
– that other guy, Commented Dec 21, 2019 at 0:00

Mark · Accepted Answer · 2019-12-21 00:58:07Z

1

Consider using egrep -q instead:

if [[ "$abc" =~ ^((git|ssh|http(s)?)|(git@[\w\.]+))(:(\/\/)?)([A-Za-z0-9.@:_/-]+)\.com(:[0-9]+)?\/([A-Za-z0-9.@:_/-]+)\/([a-zA-Z0-9_]+)(\.git)(\/)?$ ]]; then
   die "Invalid"
fi

becomes:

if  
    egrep -q "^((git|ssh|http(s)?)|(git@[\w\.]+))(:(\/\/)?)([A-Za-z0-9.@:_/-]+)\.com(:[0-9]+)?\/([A-Za-z0-9.@:_/-]+)\/([a-zA-Z0-9_]+)(\.git)(\/)?$ ]]" <<< "$abc"
then
   die "Invalid"
fi

egrep -q will return true (exit code of 0) if the regexp matches stdin (in this case we are using $abc as the stdin input.

I used egrep because you have an or expression in there (the pipes).

To be honest, I haven't tested this code, but I've used the -q option before with grep. You'll need to make sure that your regexp is correct.

answered Dec 21, 2019 at 0:58

Mark

4,5031 gold badge22 silver badges28 bronze badges

Sign up to request clarification or add additional context in comments.

1 Comment

David C. Rankin Over a year ago

Only hit with egrep (or any utility) would depend on how many times the if is called. If it is called in a loop that iterates 1M times, then that would add 1M subshells spawned dramatically slowing the script. If it's a one-off, then no issue at all.

Collectives™ on Stack Overflow

Replacing the =~ operator check in the if statement

1 Answer 1

1 Comment

Your Answer

Hot Network Questions

Collectives™ on Stack Overflow

1 Answer 1

1 Comment

Your Answer

Sign up or log in

Post as a guest

Related