Bash - exec family function to launch programs

Question

I am interested in finding which variant of the exec*() family of functions does the Bash shell use in order to launch programs. For example, the system() function uses execl(), but what does Bash use?

I did some investigation, but I want to double check with everyone if this is the right place in the Bash source code where a command entered from the terminal is executed.

I investigated Bash version 4.2.53, and found a file called execute_cmd.c. In there I observe the following chain of calls:

1. execute_disk_command()

// I think this is where bash forks a child
pid = make_child (savestring (command_line), async); 
...
exit (shell_execve (command, args, export_env)); 

2. shell_execve (command, args, env)

// I think this is where the child invokes the new program
execve (command, args, env);

Is the control flow above the right one?

Answer 1

I am not sure why you like to know that, but:

There is only one exec call that is really a syscall: execve()

All other exec*() functions are just library functions that act as frontend to execve(). Using truss(1) or clones will only show you the syscalls unless you use truss -u libc::