Question

I know that argv[0] represents the executable file name, but I don’t understand how it is implemented — how it gets the filename and options at the source code level. At first I thought it was dependent on built-in functions in linux, but then found out that windows also supports it, leading me to believe that it may be done by the compiler?

Answer 1

It’s actually part of the C99 standard, hence the same implementation across compilers and operating systems. From 5.1.2.2.1 Program startup (page 12):

If the value of argc is greater than zero, the string pointed to by argv[0] represents the program name; argv[0][0] shall be the null character if the program name is not available from the host environment. If the value of argc is greater than one, the strings pointed to by argv[1] through argv[argc-1] represent the program parameters.

Edit: Following up on Waleed Khan’s comment, you can retrieve these values via:

• Linux – /proc/self/cmdline
• OSX – _NSGetArgc / _NSGetArgv or [NSProcessInfo arguments]
• Windows – GetCommandLine() with CommandLineToArgvW()