Reverse regex logic

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# 1  
Old 09-12-2011
Reverse regex logic


I'm trying to reverse regex logic to use it in grep command. I would like to grep a string within a file that contains regex.
For example
file example.txt contains line:

And I would like to find it using
grep match123 example.txt

Is it possible?
Thank you very much for all answers!

# 2  
Old 09-12-2011
That exact command won't work of course, but perhaps:

echo match123 | grep -f matchfile

The -f tells it to interpret matchfile file as a file full of regexes, one per line.
# 3  
Old 09-12-2011
Hi Corona688, thanks for quick reply!

It's not working this way. Problem is that I nowhere found single example of same logic (to match exact string with regex or any wildcard). Maybe I just expect too much...
# 4  
Old 09-12-2011
Ah. match* If interpreted as a regex, the * here matches 0 or more h chars, so you'd match 'match', 'matchh', 'matchhhh' and so forth. If this isn't what you want, then this isn't a regex, and grep can't handle it. It looks more like a shell glob...

To match one or more of any chars your string would need to be match.*

---------- Post updated at 09:21 AM ---------- Previous update was at 09:15 AM ----------

If you have BASH or KSH:


while read LINE
        [ -z "$LINE" ] && continue # Ignore blank lines
        [[ "${STR}" == $LINE ]] && echo "$LINE"
done < globfile

Lines like match* should match the "match123". atch* wouldn't. *atch* still would.

Last edited by Corona688; 09-12-2011 at 01:27 PM..
# 5  
Old 09-12-2011
Try this untested one,
grep "match\*" file

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