BASH better way to do a look back?

Question

hey guys I'm wondering if there is a smart way to look back before a period in bash

file='foo'/bar/styles.css?ver=1.4.2

ext=$(echo ${file} | gawk -F  "?" '{print$1}')
echo "${ext##*.}" # css

Seems like I should be able to do this all in my expansion somehow?

I'm not quite sure of the goal here, but look at the `basename` command and see if it helps you with what you are trying to do. Otherwise, please provide an explanation of the expected input and the result. — Ned, Jan 14 '14 at 00:12
You should quote the `?` in `file=...?...`. It's unlikely at best that it'll match anything, but technically it could, and with the right shell options it will cause an error if it doesn't — Kevin, Jan 14 '14 at 00:34

score 2 · Accepted Answer · answered Jan 14 '14 at 00:58

2

Don't think you can do it with just one bash expansion statement (unless they can be nested somehow), works fine with two though

$ start=${file%%\?*}; echo ${start##*.}
css

answered Jan 14 '14 at 00:58

+1 - PEs can't be nested in the general case, and using two of them is exactly what we'd suggest if this question were asked in freenode's #bash. – Charles Duffy Jan 14 '14 at 01:00
@CharlesDuffy To clarify for anyone that tried nesting and succeeded (like I did), it's because you're using zsh which supports it (bash, ksh, etc don't). – mVChr Jan 14 '14 at 18:23

1 Answers1