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# 1  
Old 09-02-2011
grep using variable
how can I use grep with a variable to find a value?

Code:
 
cat data.out
Hello World
 
grep "Hello World" data.out
Hello World    ## Value found
 
I want to do something like this but can't seem to get it to work any
suggestions would be appreciated.
 
var="Hello World"
grep $var data.out

# 2  
Old 09-02-2011
In that example, it should work fine if you double-quote the variable.

If you want to ensure that the value of the variable is matched literally, use fixed-string matching, -F, to disable regular expressions. Otherwise, regular expression metacharacters could yield undesired results.

Regards,
Alister
This User Gave Thanks to alister For This Post:
BeefStu
# 3  
Old 09-03-2011
TRY THIS
TRY THIS
Code:
x=`grep -w "Hello World" data.out | wc -l`

if test $x -eq 0 ; then
      echo "String not found"
else
      echo "String found"
fi

Last edited by Franklin52; 09-03-2011 at 02:22 PM.. Reason: Please use code tags for data and code samples, thank you
# 4  
Old 09-03-2011
Quote:
Originally Posted by arindamlive
TRY THIS
x=`grep -w "Hello World" data.out | wc -l`

if test $x -eq 0 ; then
echo "String not found"
else
echo "String found"
fi
You could save yourself a little work and rewrite that so the if-statement uses grep's exit status directly (assuming the count is not needed, of course):
Code:
if grep -qw "Hello World" data.out; then
    echo "String found"
else
    echo "String not found"
fi

Regards,
Alister
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