Finding the path to a executable?

[Nick Sabalausky]

On Wed, 07 Aug 2013 09:13:03 +0200
"Tommi" <tommitissari at hotmail.com> wrote:

> On Wednesday, 7 August 2013 at 05:31:24 UTC, Alan wrote:
> > Hello!  This may seem like a simple question, maybe an 
> > embarassing question but how would I fetch the absolute path to 
> > the directory where my executable is located?  My wording is 
> > known to be confusing so I will give an example:
> >
> > cd ~/projects/program
> > dmd Program.d -ofProgram
> >
> > That executable would be located in /home/alan/projects/program 
> > for example.  SO my question is how would I fetch the absolute 
> > path to that directory?
> >
> > Thanks for any help!
> 
> This should work on at least couple of systems, but I haven't 
> tested this on other than Mac. Also, it's not completely robust, 
> because paths could be longer than 4096 chars.
> 
> version(Windows) {
>      import std.c.windows.windows;
> }
> else version(OSX) {
>      private extern(C) int _NSGetExecutablePath(char* buf, uint* 
> bufsize);
> }
> else version(linux) {
>      import std.c.linux.linux;
> }
> else {
>      static assert(0);
> }
> import std.conv;
> 
> // Returns the full path to the currently running executable
> string executablePath()
> {
>      static string cachedExecutablePath;
> 
>      if (!cachedExecutablePath) {
>          char[4096] buf;
>          uint filePathLength;
> 
>          version(Windows) {
>              filePathLength = GetModuleFileNameA(null, buf.ptr, 
> buf.length - 1);
>              assert(filePathLength != 0);
>          }
>          else version(OSX) {
>              filePathLength = cast(uint) (buf.length - 1);
>              int res = _NSGetExecutablePath(buf.ptr, 
> &filePathLength);
>              assert(res == 0);
>          }
>          else version(linux) {
>              filePathLength = readlink(toStringz(selfExeLink), 
> buf.ptr, buf.length - 1);
>          }
>          else {
>              static assert(0);
>          }
>          cachedExecutablePath = to!string(buf[0 .. 
> filePathLength]);
>      }
>      return cachedExecutablePath;
> }
> 
> // Returns the file name of the currently running executable
> string executableName()
> {
>      return executablePath().baseName();
> }
> 
> // Returns the path to the directory of the currently running 
> executable
> string executableDirPath()
> {
>      return executablePath().dirName();
> }

Yes, this is the way to do it. Never use args[0]: it's useless as it
doesn't follow symlinks (might not even follow aliases, though I'm
not certain), and strictly-speaking can't even be guaranteed to be
correct at all anyway. If it were up to me, args[0] would be eliminated
outright.