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Doubt in integer comparison

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# 1  
Old 12-07-2011
Doubt in integer comparison
Hi
What is the difference between following commands

Command1
Code:
length=1
if [[ $length > 15 ]] ; then
   echo "Hellow world"
fi

Command 2
Code:
length=1
if [[ $length -gt 15 ]] ; then
   echo "Hellow world"
fi

which is correct usage from this

Moderator's Comments:
Mod Comment Please use code tags!
Last edited by zaxxon; 12-07-2011 at 07:28 AM.. Reason: code tags
# 2  
Old 12-07-2011
Both would work on a recent version of bash, probably a version more than 3.

Otherwise use the old syntax:
Code:
if [ $x -gt 5 ]
then
    echo "hello"
fi

# 3  
Old 12-07-2011
The [[ ]] syntax is a Conditional Expression and is described in the "Conditonal Expressions" section of your Shell Manual.

The [ ] syntax is a Test and is described in the "test" Shell command which is usually a superset of the unix "test" command.

Though there is much overlap in the syntax, the two forms are not interchangeable.

Code:
Beware of this classic mistake:
a=1
b=2
if [ $a > $b ]
then
        echo ok
else
        echo not ok
fi

Replies "ok" and CREATES A FILE CALLED "2" !

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