Question

I need to have an input that looks like

./a.out <exe> <arg1> ... <argn> <others_stuff>

where <exe> <arg1> ... <argn> is the input that I must execute as a separate process (the objective is to save the exe’s output into a txt).

Saving output into a txt file isn’t a problem, I just have to redirect stdout (using dup2, freopen, or something similar).

The problem is to execute just a portion of argv! Because exec’s family functions (they are so many!) let to give as input whole argv, or specifying each arg.
I’m writing over here because I can’t solve the problem, so I hope you’re going to help me (I googled everywhere with no success).

EDIT: I forgot to say that i cannot use system for execute the command!

Answer 1

Since exec accepts an argv argument as a char* array terminated by a NULL pointer, you can just use the existing argv and set the member after the last one you want to pass to NULL.

This does destroy argv – if that’s a problem, you can copy it first (you’ll have to allocate some memory for the new copy…)