"Richard L. Hamilton" <rlhamil at smart.net> wrote:
> Is there any firm guidance on the use of long options (or the addition of
> them to commands with short options, esp. in the case where there
> might be more long options than short options)? Because whether it is this
Let me continue my last reply with some rules for commands that seem to be
needed in case long options are added:
- Every program needs to implement a "-help" option.
The program also needs to recognoze "--help" for the same purpose
to avoid confusion for GNU users.
- As there is an officiel long option called "-help", any combination of
valid single char options that result in the string "-help" is not
recognized as combination of single char options.
- If the program (before the convertion for long options) did implement
"program -h" as a way to get help, "program -help" should become an
alias.
- "program -unonkwn-option" prints at least a short syntax and a hint that
"program -help" should be used for more information.
- "program -help" or "program --help" prints an overview for all options,
one line per option.
Here is an example for this kind of online help:
mkisofs -help
Usage: mkisofs [options] [-find] file... [find expression]
Options:
-find file... [find expr.] Option separator: Use find command line
to the right
-posix-H Follow symbolic links encountered on
command line
-posix-L Follow all symbolic links
-posix-P Do not follow symbolic links (default)
-abstract FILE Set Abstract filename
-A ID, -appid ID Set Application ID
-biblio FILE Set Bibliographic filename
-cache-inodes Cache inodes (needed to detect hard links)
-rrip110 Create old Rock Ridge V 1.10
-rrip112 Create new Rock Ridge V 1.12 (default)
If the function getargs() is used instead of getopt(), command line
parsing becomes reentrant and thread safe as there are no global variables.
Options between file names may be implemented by not using a for() loop to
scan the file type arguments but alternatingly calling getargs() and getfiles()
until the return is NOARGS. In this case, "--" is only valid for the next
argument.
A simple program that implements long options (but otherwise is 100% POSIX
compliant) may look this way:
#include <stdio.h>
#include <stdlib.h>
#include <schily/schily.h>
#include <schily/getargs.h>
void
usage(int ex)
{
fprintf(stderr, "Usage: myprog [options] file...\n");
fprintf(stderr, "Options:\n");
fprintf(stderr, "-help print this help\n");
fprintf(stderr, "-verbose, -v increment verbose level\n");
fprintf(stderr, "-repeat # repeat it # of times\n");
exit(ex);
}
void
doit(int i, char *name)
{
printf("Arg %d is '%s'\n", i, name);
}
int
main(int ac, char *av[])
{
int cac = ac;
char *const *cav = av;
BOOL help = FALSE;
int verbose = 0;
int repeat = 0;
int i;
save_args(ac, av);
cac--, cav++; /* Skip av[0] */
ret = getargs(&cac, &cav, "help,verbose+,v+,repeat#",
&help,
&verbose, &verbose,
&repeat);
if (ret < 0) {
fprintf(stderr, "Bad Option '%s' (%s).\n",
cav[0], getargerror(ret));
usage(1);
}
if (help)
usage(0);
if (verbose > 1)
printf("repeating %d times\n", repeat);
for (i = 0; i < cac; i++) {
doit(i, cav[i]);
}
return (0);
}
J?rg
--
EMail:joerg at schily.isdn.cs.tu-berlin.de (home) J?rg Schilling D-13353 Berlin
js at cs.tu-berlin.de (uni)
schilling at fokus.fraunhofer.de (work) Blog:
http://schily.blogspot.com/
URL: http://cdrecord.berlios.de/old/private/ ftp://ftp.berlios.de/pub/schily
