See the exec family of functions, e.g. execl: int execl(const char *pathname, const char *arg, ...); Normally you would call it like execl("program", "progr

See the exec family of functions, e.g. execl: int execl(const char *pathname, const char *arg, ...); Normally you would call it like execl("program", "program", "argument", NULL), duplicating the program's name/path, but it's possible to set the 2nd argument, which corresponds to argv[0] (in the case of execl), to something different. This behaviour just isn't always exposed in the shell and other languages.