command line options

[Doug Gwyn]

In article <8040 at elsie.UUCP> ado at elsie.UUCP (Arthur David Olson) writes:
>> > I want some uniform way of getting programs to output their usage messages.
>> Under the existing getopts scheme, typing
>> 	command -?
>> is guaranteed to get the usage message.
>A problem and a two questions.  First, the problem:
>		No manual entry for getopts.

"getopts" is a builtin in the SVR3 and later shells; it is also built
into the current BRL version of the SVR2 shell.

I was actually referring to the getopt() library function, since that's
what the ongoing discussion was about.  A command that uses getopt()
will branch to the "error case" if you use the ? flag option.  The
normal response in the error case is to print a usage message.

>Second, the questions.  Is a public-domain implementation of "the existing
>getopts scheme," or at least a public-domain manual page, available?

AT&T placed the getopt() source code, its manual page, the now-obsolete
"getopt" utility, and its manual page into the public domain a few years
ago.  You can get this free from the AT&T UNIX System ToolChest, and I
believe it was posted to one of the sources newsgroups.

I typed up a "getopts" shell builtin manual page that I can send you,
if you can't find it in UNIX System V Release 3 documentation.

>is the scheme idiot-proof enough to work when executed in directories with
>files named, for example, "-l"?

If you have reason to believe that your command may have to handle
non-option arguments with names starting with -, then follow the
options with the -- option, which causes getopt() to stop interpreting
arguments as options.