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How to store the value of grep in a variable

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# 1  
Old 05-11-2012
How to store the value of grep in a variable
Hi ,

I was trying to store the value of a grep command to store in a variable so i can use it somewhere else in my script but i am getting error, i am using bash shell in linux:

Code:
var= `grep -n "$DATE" testfile.log | head -n 1 | sed -n 's/^\([0-9]*\)[:].*/\1/p`
echo "$var"

I get the error: unexpected EOF while looking for matching `''

If I just launch using grep, it works fine.

Also I tried the below, but doesn't print aything:

Code:
var= $(grep -n "$DATE" testfile.log | head -n 1 | sed -n 's/^\([0-9]*\)[:].*/\1/p)
echo "$var"

Can some one else tell what i am doing wrong, regards.
Last edited by methyl; 05-11-2012 at 11:23 AM.. Reason: please use code tags
# 2  
Old 05-11-2012
Your sed command is missing the closing single quote.

I would also suggest using the "$( )" format for command substitution instead of backquotes, unless you need to remain compatible with an older shell that does not support that syntax. It handles nested command substitution commands
much cleaner:
Code:
var=$(grep -n "$DATE" testfile.log | head -n 1 | sed -n 's/^\([0-9]*\)[:].*/\1/p')

Which is easier to understand, this one where you have to escape the nested backquotes:
Code:
x=`ls  \`find . -name \*.dat -print 2>/dev/null\``

Or this one, where you don't?
Code:
x=$(ls  $(find . -name \*.dat -print 2>/dev/null))

Last edited by gary_w; 05-11-2012 at 11:01 AM.. Reason: Added command substitution example
# 3  
Old 05-11-2012
Thanks for the reply but after using
Code:
var= $(grep -n "$DATE" Activity.log | head -n 1 | sed -n 's/^\([0-9]*\)[:].*/\1/p')
echo "$var"

, i get command not found error and prints the value of the grep.
It still not printing the value of this command -
Code:
echo "$var"

so the value of grep is still not storing in the variable 'var'
Last edited by methyl; 05-11-2012 at 11:24 AM.. Reason: please use code tags
# 4  
Old 05-11-2012
Please show a sample input line from Activity.log and your output and verify the contents of your $DATE variable.

Please use code tags too, for readability.
# 5  
Old 05-11-2012
Quote:
var= $whatever
After using code tags, we can see every space character.
Look carefully at gary_w's post and then lose the space character after the equals sign.
Code:
var=$whatever

# 6  
Old 05-11-2012
Thanks gary_w and methyl, it worked after correcting the space, i am using space after "=" sign .
This User Gave Thanks to learninguser235 For This Post:
methyl
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