Describe the bug

The section String Expression showcases an example with -v to check if a shell variable is set that I think is used incorrectly.

For the -v condition to work as expected it should be used as

[[ -v VARNAME ]] 

rather than the current

[[ -v ${varname} ]] 

But I could be mistaken or misunderstood something.

To Reproduce

1. Create the following bash script test_string_expressions.sh:

#!/bin/bash VARNAME="Test" if [[ -v ${VARNAME} ]]; then echo "Shell variable is set. Value: ${VARNAME}" else echo "Shell variable is not set" fi 

2. Execute the script
3. See script output: Shell variable is not set. But the variable is set.

Expected behavior

The script should output: Shell variable is set. Value: Test.

The -v operator in Bash checks if a variable name exists, not its value. Specifically, one should pass the name of the variable directly to -v, not its dereferenced value (${VARNAME}). Here's how i think it should be:

[[ -v VARNAME ]]