-----BEGIN PGP SIGNED MESSAGE----- Hash: SHA1 According to Chet Ramey on 2/23/2009 1:16 PM: > OK. Let me try to explain how the current behavior derives from Posix. > > It falls under two parts of the standard (section 1.4): > > 1. Unless otherwise stated in the utility description, when given an > option unrecognized by the implementation, or when a required > option-argument is not provided, standard utilities shall issue a > diagnostic message to standard error and exit with a non-zero exit > status. > > 2. Default Behavior: When this section is listed as "None.", it means > that the implementation need not support any options. [...] > > So return doesn't accept any options, and is required to exit when an > unrecognized option is seen.
However, there is nothing that *requires* that -1 be rejected as an unknown option. Consider the case of 'tail -1'. When textutils 2.0.21 made the change--quoting POSIX as the reason--that users *had* to type 'tail -n -1', there was enough of an uproar that the Austin group ended up issuing a clarification, making it explicit that while POSIX does not require support for 'tail -1', it also does not forbid implementations from providing it as an extension. Hence, coreutils 5.90 and later now support, as an extension, the older 'tail -1' syntax in addition to the POSIX-compliant 'tail -n -1'. The same argument is worthwhile for exit/return. Although POSIX does not require support for any options, neither does it forbid it. Thus, making 'return -1' behave like 'return 255', as an extension, is still permitted, and in the interest of backwards-compatibility, is probably also the nicest thing we can do. - -- Don't work too hard, make some time for fun as well! Eric Blake e...@byu.net -----BEGIN PGP SIGNATURE----- Version: GnuPG v1.4.9 (Cygwin) Comment: Public key at home.comcast.net/~ericblake/eblake.gpg Comment: Using GnuPG with Mozilla - http://enigmail.mozdev.org iEYEARECAAYFAkmjbmIACgkQ84KuGfSFAYDG5gCdFqvNRIGHubQsbsv7kZg7/bc1 3+EAnjSwa4lhCUjTBp5boWGf6nf569wJ =eQn6 -----END PGP SIGNATURE-----
