Contents of argv[0]

[Oliver Laumann]

In article <1017 at virtech.UUCP> cpcahil at virtech.UUCP (Conor P. Cahill) writes:
> On most, if not all, unix systems argv[0] will contain the path used to 
> execute the program (i.e. the first argument to an execl()).  This may be
> a relative path, a full path and/or a simple name.  Your code should handle
> all cases.

You should also anticipate the case that argv[0] is not there (i.e. argc
is zero).   It is perfectly valid to execute a program like this:

    execl (your_program, (char *)0);

The manual only says that ``by convention'' at least one argument must
be passed to the program.  However, this is not enforced.  For a good
laugh compile the following program:

    main (ac, av) char **av; {
	execl (av[1], (char *)0);
	perror ("exec");
    }

and then try, for instance,

    % a.out /bin/ls
    % a.out /usr/ucb/mail
    % a.out /bin/csh
    % a.out /usr/ucb/vi
    % a.out /bin/size

Regards,
--
Oliver Laumann              net at TUB.BITNET              net at tub.UUCP