Special test condition which inhibits code execution unless the script being executed is the top-level script. This is useful for adding special self-test conditions to libraries so that they can be executed directly.
Example:
#!/usr/bin/env shlib
__shlib_hello() { printf 'Hello World\n'; }
alias shlib.hello='__shlib_hello '
shlib.main { shlib.hello; }In this example the contents of the shlib.main block will not be executed
during import shlib.hello, but instead will only be executed if the
hello.shlib file is executed directly.