How can an executing program determine its own pathname?
Your program can look at argv[0]; if it begins with a “/”, it is probably the absolute pathname to your program, otherwise your program can look at every directory named in the environment variable PATH and try to find the first one that contains an executable file whose name matches your program’s argv[0] (which by convention is the name of the file being executed). By concatenating that directory and the value of argv[0] you’d probably have the right name. You can’t really be sure though, since it is quite legal for one program to exec() another with any value of argv[0] it desires. It is merely a convention that new programs are exec’d with the executable file name in argv[0]. For instance, purely a hypothetical example: #include main() { execl(“/usr/games/rogue”, “vi Thesis”, (char *)NULL); } The executed program thinks its name (its argv[0] value) is “vi Thesis”.
