Question

I’m attempting to find out how to use sh -c or bash -c properly.

I can easily run a simple command like "sh -c ls" without arguments.

The problem comes when I’m trying to add in arguments.
To do ls -ltga, I’ve had to do:

sh -c "ls -ltga"

This wouldn’t be a big issue, except I’m attempting to write my own small shell program,
and when I use execve I try:

Argument #:  string
         0:  sh
         1:  -c
         2:  "ls
         3:  -ltga"

And it gives me an error, saying that it reached an EOF before finding the next '"'

I’ve also tried:

         0:  sh
         1:  -c
         2:  "ls -ltga"

and it returned to me saying that it couldn’t find the file/script named "ls -ltga"

Does anybody know what I am doing wrong?

Answer 1

You shouldn’t put quotes inside arguments of execve(). It should be called like this:

char *args = { "sh", "-c", "ls -ltga", 0};
execve("/bin/sh", args);

The first argument to execve() must be the path to the executable (usually a full path).