While I agree with Dirk Herrmann that basename is the right tool for the job, I think it is still worthwhile to know how to do it with grep, because you might one day encounter a sufficiently similar situation that is not covered by a specialised tool.

The question can be broken into two questions:

1. What regular expression matches exactly the part after the last slash.

2. How to get grep to only output the part that matches, instead of the whole line.

For the first question, note that the part after the last slash is characterized by the fact that it doesn't contain a slash (otherwise the previous slash would not have been the last one) and extends to the end of the line.

To match a character that's anything but a slash, you can use [^/]. You want to match any number of them, so put a star afterwards: [^/]*. But you only want to match it if it extends to the end of line (so you do not match e.g. the branches in your example), this is done by terminating the regular expression with a dollar sign. So the complete regular expression you need is [^/]*$

For the second question, the option -o does exactly what you need. From the man page:

       -o, --only-matching
              Print  only  the  matched  (non-empty) parts of a matching line,
              with each such part on a separate output line.

So putting it all together, we get the desired behaviour:

$ echo "branches/features/arm_and_musl" | grep -o '[^/]*$'
arm_and_musl

posted over 2 years ago

CC BY-SA 4.0

celtschk‭

771 reputation 8 12 97 2