find a substring inside a bash variable

Question

we were trying to find the username of a mercurial url:

default = ssh://someone@acme.com//srv/hg/repo

Suppose that there's always a username, I came up with:

tmp=${a#*//}
user=${tmp%%@*}

Is there a way to do this in one line?

Answer 1

Assuming your string is in a variable like this:

url='default = ssh://someone@acme.com//srv/hg/repo'

You can do:

[[ $url =~ //([^@]*)@ ]]

Then your username is here:

echo ${BASH_REMATCH[1]}

This works in Bash versions 3.2 and higher.

Answer 2

You pretty much need more that one statement or to call out to external tools. I think sed is best for this.

sed -r -e 's|.*://(.*)@.*|\1|' <<< "$default"

Answer 3

Not within bash itself. You'd have to delegate to an external tool such as sed.

Answer 4

Not familiar with mercurial, but using your url, you can do

echo 'ssh://someone@acme.com/srv/hg/repo' |grep -E --only-matching '\w+@' |cut --delimiter=\@ -f 1

Probably not the most efficient way with the two pipes, but works.