Propagate exit value, xterm

eddchr · 10-20-2008, 08:05 AM

Hi,

We have a little scenario regarding how exit/return values gets propagated when executing a command via, for example, xterm.

Example program:

Code:

int main(){ return 123;}

What we need is to receive the return value above (123) when running the following command:

Code:

xterm -e ./example_program

The actual value we receive is the return value from xterm, which in the most cases are zero, and not 123..

Any ideas?

Hko · 10-20-2008, 08:51 AM

As w workaround you could save the exit code of your program to a temp file:

Code:

bash:/tmp$ cat eksit.c
int main()
{
    return 67;
}
bash:/tmp$ gcc -o eksit eksit.c
bash:/tmp$ xterm -e '/tmp/eksit ; echo $? >/tmp/exitcode'
bash:/tmp$ cat /tmp/exitcode 
67

ta0kira · 10-20-2008, 03:34 PM

This might be a start, if you really need it to be inlined.

Code:

//outer.c


#include <unistd.h>
#include <sys/types.h>


int main(int argc, char *argv[])
{
    int pipes[2] = { -1, -1 };
    pipe(pipes);

    pid_t new_process = fork();


    if (new_process < 0) return 1;


    if (new_process == 0)
    {
    dup2(pipes[1], 3);

    if (pipes[0] != 3) close(pipes[0]);
    if (pipes[1] != 3) close(pipes[1]);

    execvp(argv[1], argv + 1);
    }


    else
    {
    close(pipes[1]);

    waitpid(new_process, NULL, 0x00);

    int outcome = 0;
    read(pipes[0], &outcome, sizeof(outcome));

    return outcome;
    }


    return 1;
}

Code:

//inner.c


#include <unistd.h>
#include <sys/wait.h>


int main(int argc, char *argv[])
{
    int outcome = WEXITSTATUS( system(argv[1]) );
    write(3, &outcome, sizeof(outcome));
    return 0;
}

Code:

bash> gcc outer.c -o outer
bash> gcc inner.c -o inner
bash> ./outer xterm -e "./inner 'ls nothere'" || echo "'nothere' isn't here"
'nothere' isn't here
bash> ./outer xterm -e "./inner 'ls outer'" && echo "'outer' is here"
'outer' is here

It doesn't have the normal error checks, but it's a general idea of how you might do it.
ta0kira