Unary Operator Expected in Bash
I've Seen Questions Regarding the Same Issue, but All of Them Are About Strings. How About Integers? Why Am I Getting the "Unary Operator Expected" Error? If [...
I've seen questions regarding the same issue, but all of them are about strings. How about integers? Why am I getting the "unary operator expected" error?
if [ $(date +%k%M) -ge ${!BLOCK1FRAN} ] ; then whatever ; fi
2 Answers
You are using indirection. If the variable ${BLOCK1FRAN} points to an empty variable, you'll get the error message. Make sure that the variable pointed by ${BLOCK1FRAN} contains a valid numeric value.
If you want an empty string and nonnumeric values to be evaluated as zero (0), use the following syntax.
if [[ $(date +%k%M) -ge ${!BLOCK1FRAN} ]]; then whatever ; fi
It looks good to me. Are you sure you've set BLOCK1FRAN correctly?
whatever() { echo "it works"; }
foo=42
BLOCK1FRAN=foo
if [ $(date +%k%M) -ge ${!BLOCK1FRAN} ] ; then whatever ; fi
it works
James Sterling reports on renewable energy developments, climate policy, ecological conservation, and green tech innovations around the globe.
