bash: unbound variable

[Greg B_1]

when I execute a shell script containing:
(and expecting to get one of the two statements echoed)

if [ $greg = "test" ]; then
echo "greg equal to test"
else
echo "greg not equal to test"
fi

I get:
bash: greg: unbound variable

Can anyone explain what's the deal there?

[RAC_1]

how shell is supposed to find greg? you are defining it anywhere in the script.

It should be
grep=test
if [ $greg = "test" ]; then
echo "greg equal to test"
else
echo "greg not equal to test"
fi

This will give greg eqal to test

[Deepak Extross]

An unbound variable is one that has not been defined.

Try checking for existence of the variable using the test -z option before doing any comparison:
if [ -z $greg ]; then
....

[T G Manikandan]

///define greg//

greg=test
or
greg=test1


if [ $greg = "test" ]
then
echo "greg equal to test"
else
echo "greg not equal to test"
fi