# [ > Evaluate condition. > Returns 0 if the condition evaluates to true, 1 if it evaluates to false. > More information: . - Test if a given variable is equal to a given string: `[ "{{$VARIABLE}}" == "{{/bin/zsh}}" ]` - Test if a given variable is empty: `[ -z "{{$GIT_BRANCH}}" ]` - Test if a file exists: `[ -f "{{path/to/file}}" ]` - Test if a directory does not exist: `[ ! -d "{{path/to/directory}}" ]` - If-else statement: `[ {{condition}} ] && {{echo "true"}} || {{echo "false"}}`