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/manual/html_node/test-invocation.html.

• 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"