Re: How to find directory where the program is?

[Thierry Lelegard <thierry.lelegard@canal-plus.fr>]

Preben Randhol wrote :
> 
> How can one in Ada95 find out from which directory the Ada program is
> stored in.  I mean I need to find out if my program is stored in
> /usr/bin/ or /usr/local/bin or some other directory. Does anybody know
> how I can do this. Note that current directory is not equal to the
> directory the program is stored in. I use GNAT so if GNAT has some
> routines for this that I have missed, please tell me. I'll make it
> portable later if needed.

It entirely depends on the operating system. On UNIX, getting argv[0]
is not reliable since there are some flavors of exec (such as execve)
which allow the caller to set argv[0] to something different from the
program name (see a login shell: argv[0] is "-sh" while the program name
is "sh" without leading dash).

To get the full path name, we use system-dependent techniques,
usually using the /proc filesystem on UNIX. However, the usage
of the the /proc filesystem depends on the UNIX flavor.

It works fine on Solaris and Linux (enter "man proc"). On HP-UX,
there is no /proc file system and we use pstat_getproc. HOwever,
it returns the basename only.

On the other OS we use (OpenVMS and Windows, although Windows can hardly
be considered as an OS :-(), there are dedicated system calls to get
the full pathname of the program.

-Thierry
____________________________________________________________________________

Thierry Lelegard, "The Jazzing Troll", CANAL+ Technologies
____________________________________________________________________________