system() Statuscode

[Frank Liebelt]

Hi

I am a beginner in c++.

In my little program i would unpack a tar file with a system call.
system("tar -xfv unpack.tar");

Is it possible to check that the tar command was successfull or not?
I know system() gives -1 on error, 0 on OK but how to check tar was
successfull?

I thought about if (access(... but i hope there is a better way to do this.

Frank

[Phlip]

Frank Liebelt wrote:

In my little program i would unpack a tar file with a system call.
system("tar -xfv unpack.tar");

Is it possible to check that the tar command was successfull or not?
I know system() gives -1 on error, 0 on OK but how to check tar was
successfull?

Use popen (or _popen), and read each line returned from the call. Parse the
line to find success or failure indicators. Then use pclose to get the final
return value.

--
Phlip
http://www.greencheese.org/ZeekLand <-- NOT a blog!!!

[Frank Liebelt]

Phlip wrote:

Frank Liebelt wrote:

In my little program i would unpack a tar file with a system call.
system("tar -xfv unpack.tar");

Is it possible to check that the tar command was successfull or not?
I know system() gives -1 on error, 0 on OK but how to check tar was
successfull?

Use popen (or _popen), and read each line returned from the call. Parse the
line to find success or failure indicators. Then use pclose to get the final
return value.

I tried this but it wont work:

bool unpack(int value)
{
FILE *tar;
char buf[128];

switch (value)
{
case 1:
if ((tar = popen("tar -xf /tmp/mytar.tar -C /home/user1", "rt")) == NULL)
return false

if (pclose(tar) == 0)
return true;

return false;
break;
}
case 2:
if ((tar = popen("tar -xf /tmp/mytar.tar -C /home/user2", "rt")) == NULL)
return false

if (pclose(tar) == 0)
return true;

return false;
break;
}

}

It doesnt work cause this gives allways false
if ((tar = popen("tar -xf /tmp/mytar.tar -C /home/user", "rt")) == NULL)

tar is installed an this command works in the console with no probs.

Frank

[Aaron Isotton]

Frank Liebelt wrote:

It doesnt work cause this gives allways false
if ((tar = popen("tar -xf /tmp/mytar.tar -C /home/user", "rt")) == NULL)

tar is installed an this command works in the console with no probs.

Maybe you need to give the full path of tar. Anyway, that's rather a
question for comp.unix.programmer.

Greetings,
Aaron