UNIX for Dummies Questions & Answers

Ok so I can use awk to match a pattern and print the whole line with print $0. Is there any way to just tell awk to print every line of output when the pattern matches?

I'm having it wait for the word error and then print that entire line. But what I actually need to see is all the following lines after the line with the error. So there has got to be some easy way to just tell awk to print everything when there is a pattern match?

Print all line containing 'toto' in file called 'tst' :

Code:

# cat tst
zroezp toto rueziar
roez tutu uezir
roezp toto reziar
zroezp titi rueiar
roezp toto ruezar
roezp tata rueziar
zroezp titi rziar
zroep toto rzir
zrezp tata ruziar
zezp toto rziar
roezp toto rueziar

Code:

# awk '/toto/' tst
zroezp toto rueziar
roezp toto reziar
roezp toto ruezar
zroep toto rzir
zezp toto rziar
roezp toto rueziar

does it mean, you want all lines that after the line which match word "error" the very first time?

like

Code:

1 blah blah blah
2 oops error
3 error again
4 ok hello world
5....
....
100...

what you are looking for are lines ( 3- 100) ?

then try this:

Code:

awk '{ if (!a && $0~/error/) {a=1;next;}} a'

or

Code:

 awk '/error/,0'  yourInputFile | awk 'NR>1'

I'll have to try this when I get back into work again. But, basically I'm looping a simple command and I only want to see output when it errors. The rest of the time I don't care and don't want to see anything.

Code:

 while true ; do command | awk '/error/{print $0 , system ("date")}'  ; sleep 1 ; done

The commands output is either going to be OK or error followed by lines of information about the error and why it occured. Could be 3 lines could be 10 you never know. But I need to leave this running for hours and hours. I didn't want to see 10,000 lines of this

OK
OK
OK
OK
OK
OK
Error
OK
OK

So I am just doing the simple awk command so that it only prints the line when it actually fails and gives me an error. My only issue at this point is that I get the Error line but none of the follow up lines. So at least I know when it fails but, I have no details on why.

I see what u mean. it would be good if you could give an example with boundaries, how to distinguish ERROR, detailed error messages and normal output.

without knowing the format of your inputFile, no one could help.

There is no input file its a simple command and the results of the command are my input. There is no way to know what the output will be when the error occurs nor how many lines. I can presume it would be no more than say 10 lines at most. That's why I was hoping I could just find some way to say. If you see this word then print all output that can be printed.

---------- Post updated at 09:06 PM ---------- Previous update was at 05:54 PM ----------

Code:

 awk '{ if (!a && $0~/error/) {a=1;next;}} a'

Well I did this and it is partially successful. It does print the lines after the match. However it doesn't print the original line with the error on it. Thats not critical and I could live without it. Would be cleaner if the original error line printed also.

However the pattern match doesn't seem to work as my original command did. It runs subsequent date command every time it runs the command regardless of a match to the pattern.

Code:

 while true ; do command | awk '{ if (!a && $0~/failed/system ("date")) {a=1;next;}} a' ;sleep 2; done

I wind up getting this as my output when the output is OK. Ideally I only want to see any output when it fails. So I gotta figure out how to get the Date command to only execute when the pattern matches.

Thu Apr 7 19:00:24 PDT 2011
Thu Apr 7 19:00:26 PDT 2011
Thu Apr 7 19:00:28 PDT 2011
Thu Apr 7 19:00:32 PDT 2011
Thu Apr 7 19:00:34 PDT 2011
Thu Apr 7 19:00:36 PDT 2011

So I have two 50% answers so far. I just need to combine the two into one perfect command. But, must sleep!!!!

Post some lines of the output with the OK and Error lines and the desired output.