Check a value of a variable 2

[Autosys]

Hi,

I'm farely new to Unix and was wondering if you could tell me how to check that a variable $TEST has a value assigned to it?

Do I do something like:

if [ $TEST = "" ] then
$EXITVAL=100
exit $EXITVAL

or is there a better way? Your help will be very much appreciated!

S

 

[columb]

if [ -z "$TEST" ]
then
  EXITVAL=100
fi
exit $EXITVAL

or

[[ -z "$TEST" ]] && EXITVAL=100
exit $EXITVAL

 

[mrjazz]

Hi Autosys,

Your script is syntactically wrong. The "if" command has to be closed with a "fi".
Using the Korn shell you can use the following command to check whether a variable is or is not assigned: [[...]].
If the expression in the brackets is true, you will get an exit status of zero, otherwise a non-zero exit status.

In your case you can use:

[[ -z $TEST ]] && print "Variable is not assigned" || print "Variable is assigned"

[[ -z $TEST ]] checks for a zero string. The following output from the print commands are depending on the exit status of the [[...]] expression.

HTH

mrjazz

 

[Ygor]

In ksh you also have another option:

[ ${TEST:?} ]

If the variable is not set it will abort the script with an error.

 

[dchoulette]

if [[ -z "$TEST" ]]

will check if $TEST is unassigned or assigned an empty value.

If you really want to check that no value was assigned, even an empty one:

if [[ -z "${TEST+assigned}" ]]; then
   echo "TEST is unassigned"
fi

--------------------

Denis