Accepting Shabang Scripts (Quick & Easy Question, Just Can't Find Answer)

overbored · 03-24-2004, 04:12 PM

I'm interested in writing a program that I can use to run shabang scripts.

Here is the program, /home/joe/main.c:

Code:

int main(int argc, char** argv) {
        char blah[256];
        if (argc > 0) {
                printf("cmd: %s\n", argv[0]);
        }
        scanf("%s", blah);
        printf("stdin: %s\n", blah);
}

I compile it with "gcc -o /home/joe/main /home/joe/main.c".

Here's the script, /home/joe/tryme:

Code:

#!/home/joe/main
hubba hubba

But when I run /home/joe/tryme, it doesn't read the file into stdin (that was my guess), but instead waits for stdin from the prompt (i.e., exact same behavior as I get when running /home/joe/main).

I tried Googling for answers, but all I get (unsurprisingly) is material on the scripting side of things, not on the programming side. How do these scripts work, exactly? Thanks in advance.

ilikejam · 03-24-2004, 05:55 PM

Perhaps you would have more luck getting the program to invoke 'bash script_name'

I'm not entirely sure why you would want to write a program to do this, though.........

Dave

aluser · 03-24-2004, 05:56 PM

The #! gives the filename of the script to your program as the first argument, not through stdin. You then get to open the file yourself.

btw, argc is 1 when the program is called with no arguments: argv[0] is normally the program's name.

overbored · 03-24-2004, 06:41 PM

Ah, I see it - the first argument. Thanks!