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grep to handle a 0 result

 
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# 1  
Old 02-05-2007
grep to handle a 0 result
Hi guys,

I have the following grep command in a script to search through a file for a string and return its count, and it works fine for when the string exists:

grep "string" file.txt | wc

However, sometimes the result will be 0 and I want the script to take this as the result. Right now it is just dumping out with a "child process exited abnormally"

How can I get around this so that if the result is 0 then the script doesnt dump out and takes the result as 0?

thanks
# 2  
Old 02-05-2007
Code:
grep -c 'string' file.txt

# 3  
Old 02-05-2007
Can you please post your script here? Let us see what exactly you are trying to acheive.
# 4  
Old 02-05-2007
I have tried grep -c but that doesnt work either, it keeps on dumping out.

The script is actually a TCL script with embedded UNIX commands. The part its failing on is like so:

set td [exec grep -c "InvalidMessage" $logdir/$t | wc -l]

(I have assigned the variables logdir and t from before)

and i run the script and this occurs:

child process exited abnormally
while executing
"exec grep -c "InvalidMessage" $logdir/$t | wc -l"


It happens because there are no "InvalidMessage" strings in the file, but I know this and want the result i.e. 0 to be assigned to td
# 5  
Old 02-05-2007
grep -c "string" also gives you the count of lines then why are you still piping the output to wc -l, it'll always give you the output as "1", please remove it and try.
# 6  
Old 02-05-2007
Hi,

I removed the wc -l as well. That too didnt work and the result kept on dumping out again...

note: The double quotes i have used are correct in this instance, as this is how a UNIX command is executed in TCL
# 7  
Old 02-05-2007
Quote:
Originally Posted by ocelot
Hi,

I removed the wc -l as well. That too didnt work and the result kept on dumping out again...

note: The double quotes i have used are correct in this instance, as this is how a UNIX command is executed in TCL
See this link: http://wiki.tcl.tk/8489

Regards,
Tayyab
 
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