[KraziKid]

I was wondering if it is possible for my C++ program to read the output of a system call. For instance, say I use the stdlib function system() to call "ls ~/" how can I read this in to a string, or an array, or anything? I need to keep track of the output of some other programs. Is there any other way to do this without using system?

[Angus_D]

Not using system(), but using popen().

[samm]

here is some quick C code using popen:

Code:
#include <stdio.h>
#include <stdlib.h>

int main() {
    FILE* foo = popen("ls -l", "r");
    if (foo == NULL) return -1;

        char fooBuffer[128];
        while(!feof(foo)) {
            if (fgets(fooBuffer, 128, foo) != NULL) {
                printf( "%s", fooBuffer);
            }
        }

        pclose(foo);

        return 0;
}

[KraziKid]

Originally Posted by samm

here is some quick C code using popen:

Code:
#include <stdio.h>
#include <stdlib.h>

int main() {
    FILE* foo = popen("ls -l", "r");
    if (foo == NULL) return -1;

        char fooBuffer[128];
        while(!feof(foo)) {
            if (fgets(fooBuffer, 128, foo) != NULL) {
                printf( "%s", fooBuffer);
            }
        }

        pclose(foo);

        return 0;
}

Thanks for the help. Is there any way to do this using C++ and streams?

[samm]

Originally Posted by KraziKid

Thanks for the help. Is there any way to do this using C++ and streams?

There is no portable way to convert the FILE pointer to a C++ istream. There are some gnu extensions to g++ that may do this, but I am not sure. The C code I posted above should work just fine in a C++ compiler, why do you want to use streams?

[KraziKid]

Originally Posted by samm

There is no portable way to convert the FILE pointer to a C++ istream. There are some gnu extensions to g++ that may do this, but I am not sure. The C code I posted above should work just fine in a C++ compiler, why do you want to use streams?

I'm more comfortable working in C++ code rather than a mixture of C and C++. I do not know "pure" C.

I am also only going to be working with Darwin based systems for this.

[Chuckit]

Originally Posted by KraziKid

Thanks for the help. Is there any way to do this using C++ and streams?

This seems to be what you want.

[Angus_D]

Originally Posted by KraziKid

I'm more comfortable working in C++ code rather than a mixture of C and C++. I do not know "pure" C.

If you don't know "pure" C, then you don't know C++, period. C++ is a superset of C.

[fortezza]

What if you want to start a process and then exit immediately without terminating the process you started? Say you have a program that checks to make sure important system processes are running, starts any that are not running, and then exits?

[parallax]

fortezza: check out the man pages for fork and execvp...