# test
# Check file types and compare values.
# Returns 0 if the condition evaluates to true, 1 if it evaluates to false.
# More information: <https://www.gnu.org/software/coreutils/test>.
# Test if a given variable is equal to a given string:
test "$MY_VAR" == "/bin/zsh"
# Test if a given variable is empty:
test -z "$GIT_BRANCH"
# Test if a file exists:
test -f "path/to/file_or_directory"
# Test if a directory does not exist:
test ! -d "path/to/directory"
# If A is true, then do B, or C in the case of an error (notice that C may run even if A fails):
test condition && echo "true" || echo "false"
$
cheat.sh
tldr