Testing : sh -u : Unbound variable

Today came across a good feature "-u" in shell. This will make the script to error when it comes across a undefined variable. If otherwise ,the undefined variable will expanded to nothing,

Running the script with "-u" option checks for the variables is not defined then throws the error "unbound variable"

Lets do it with a example,


$ cat t.sh
TEST=""
echo "Test"
echo $TEST

Running the script with "-u" option,

$ sh -u t.sh
Test

Now removing the Variable assignment and running the script,

$ cat t.sh
echo "Test"
echo $TEST

$ sh -u t.sh

Test

t.sh: line 5: TEST: unbound variable