File: coreutils.info, Node: true invocation, Next: test invocation, Prev: false invocation, Up: Conditions 16.2 `true': Do nothing, successfully ===================================== `true' does nothing except return an exit status of 0, meaning "success". It can be used as a place holder in shell scripts where a successful command is needed, although the shell built-in command `:' (colon) may do the same thing faster. In most modern shells, `true' is a built-in command, so when you use `true' in a script, you're probably using the built-in command, not the one documented here. `true' honors the `--help' and `--version' options. Note, however, that it is possible to cause `true' to exit with nonzero status: with the `--help' or `--version' option, and with standard output already closed or redirected to a file that evokes an I/O error. For example, using a Bourne-compatible shell: $ ./true --version >&- ./true: write error: Bad file number $ ./true --version > /dev/full ./true: write error: No space left on device This version of `true' is implemented as a C program, and is thus more secure and faster than a shell script implementation, and may safely be used as a dummy shell for the purpose of disabling accounts.