I need to redirect lines from stdout to a file, but just those containing certain string1 or not containing certain string2. How can I do that? I just know how to do that separatelly (either lines containg a string1 or lines not containing a string2). It doesn't have to be grep, just something I can use in a pipe in a terminal.
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3 Answers
Perl to the rescue!
perl -ne 'print if /string1/ || ! /string2/' < file
-nreads the input line by line/string1/is a regex match||means "or",!means "not"
You can pipe to awk:
your_process | awk '$0!~/string2/ || $0~/string1/{print $0}'
If the line being processed does not contain "string2": $0!~/string2/
OR if the line being process does contains "string1": $0~/string1/
Then print the line: {print $0}
As @Mischa shared in the comments, you can get very terse with awk. This can be written as:
your_process | awk '/string1/ || !/string2/'
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There is
orin the question notand, but I just change&&I guess.– T.PoeCommented Dec 21, 2017 at 20:39 -
{print $0} is the default. For tersaholics: ... | awk '/string1/ || !/string2/'– MischaCommented Dec 21, 2017 at 20:41
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@T.Poe Sorry about that.
OR NOTsounds weird and my brain decided it couldn't handle it. Just change that&&to||and I think that should work fine for you.– JNevillCommented Dec 21, 2017 at 20:44 -
It doesn't seem to work. When I reditect to the file with
>it doesn't write anything. Withteeit writes something but it stops writing after a while (very quickly), I don't understand that. I tried it with just one statement, without OR, still nothing. My command literally looks like this:nohup python ./script.py | awk '!/string/' | tee out.txtor> out.txtinstead of| tee.– T.PoeCommented Dec 21, 2017 at 21:03 -
I believe that's due to your
nohup. Check out this answer for doing a pipe with nohup.– JNevillCommented Dec 21, 2017 at 21:05
You can try something like this:
tail -f {SOMETHING} | grep string1 | grep -v string2 >> /tmp/out.log
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it is worth to consider "line buffered" output as you are getting input from
tailand passing it to 2grepprocesses. (Hello from Kyiv) Commented Dec 21, 2017 at 21:11 -
@RomanPerekhrest Main idea - is to use
grep string1for match desired strings andgrep -v string2to exclude non-interested strings, all the - rest just for sake of example.– cn0047Commented Dec 21, 2017 at 22:01