How To In Unix:String Comparison In Unix...

Today I learnt another important thing in Unix shell scripts.Till today I just used variables to store integer.And wil the same blur idea I was vainly trying to compare strings.My script was like :

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LATESTLOG="anything";
LATESTLOG=`ls -lrt $SCRIPT_NAME.*.log|tail -1|cut -d":" -f2|cut -d" " -f2`;
if [ $LATESTLOG -ne "anything" ];
then
echo "Do something";
else
echo "Do nothing";
fi
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And the error was coming like:
<-----bad number----->

Later I understood that string comparison is different in shell script and integer comparison is different.
As we know in integer comparison

-eq

is equal to

if [ "$a" -eq "$b" ]

-ne
is not equal to

if [ "$a" -ne "$b" ]

-gt
is greater than

if [ "$a" -gt "$b" ]

-ge
is greater than or equal to

if [ "$a" -ge "$b" ]

-lt
is less than

if [ "$a" -lt "$b" ]

-le
is less than or equal to

if [ "$a" -le "$b" ]


So here the comparison was wrong.I was to compare strings which I was performing like integer comparison.
In string conparison,there are a lots of things,I will put down all those things slowly.For now the basic string comparison is like:

is equal to

if [ "$a" = "$b" ]

is not equal to

if [ "$a" != "$b" ]

So the rectified portion of my script became:

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LATESTLOG="anything";
LATESTLOG=`ls -lrt $SCRIPT_NAME.*.log|tail -1|cut -d":" -f2|cut -d" " -f2`;
if [ $LATESTLOG != "anything" ];
then
echo "Do something";
else
echo "Do nothing";
fi
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