Support - in optstring for getopt
POSIX states that implementations may support other characters than those specified in "Utility Syntax Guideline 3" as option arguments for
getopt. One common extension which I have verified in glibc, FreeBSD's libc, and macOS's libc, is to support
-. This allows for an interesting trick if
-: is supplied in
opstring, allowing for emulation of long options without needing
getopt_long (which is not in POSIX), though without easy support for arguments (some
optind hacking could allow for arguments, though).
At the moment, Sortix rejects
getopt calls with
optstring, so a program attempting to use this trick is unable to accept any arguments.