Need Help with Simple Regex

evilfreakz · #1 (**permalink**) 08-31-2008

I have got a question. How to do this? I mean AND expression in regex.

List all the files in current directory that do not contain the words use AND take.

Thx.

era · #2 (**permalink**) 08-31-2008

Assuming you want an answer rather than a theory, something like

Code:

for f in *; do
  grep use "$f" >/dev/null && continue
  grep take "$f" >/dev/null && continue
  # file contains neither if we get to here; report its file name
  echo "$f"
done

If you really do require this to be done in regular expressions exclusively, there is no simple way to specify this in regular expressions. Theoretically there could be an operator & to parallel the operator | but in practice, it is fairly useless, and also complicates the regex engine a fair bit (if I recall the gist of the research papers on this topic correctly).

Lakris · #3 (**permalink**) 08-31-2008

From the top of my head, I would use something like

Code:

grep -L use $(grep -L take *.txt)

which means, first (in the prenthesis) find all files that do not contain the word take, and in that list of files, find all the files that do not contain the word use.
But I'm sure there is a way to use OR in the regexp..

/Lakris

Franklin52 · #4 (**permalink**) 08-31-2008

Use egrep, search for $var1 OR $var2:

Code:

egrep "[$var1]|[$var2]" file

Invert match:

Code:

egrep -v "[$var1]|[$var2]" file

Search for $var1 AND $var2:

Code:

egrep "$var1.*$var2|$var2.*$var1" file

Invert match:

Code:

egrep -v "$var1.*$var2|$var2.*$var1" file

Regards

ghostdog74 · #5 (**permalink**) 08-31-2008

i think OP means the words "use" and "take" should not be in the file. So the egrep solution will not work is "use" and "take" are on separate lines.

Franklin52 · #6 (**permalink**) 08-31-2008

Quote:

Originally Posted by ghostdog74

i think OP means the words "use" and "take" should not be in the file. So the egrep solution will not work is "use" and "take" are on separate lines.

Sorry, just awake

, I have to read the question thoroughly.

Regards

Lakris · #7 (**permalink**) 08-31-2008

I guess I misinterpreted the OP, now here is my supersilly superuseless use of cat and pipe...

Code:

for x in *.txt;do cat $x|tr "\n" " "|egrep '(use.*take|take.*use)'&>/dev/null; [ $? == 1 ] && echo $x;done

but I think it gets the job done?

/Lakris

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