a problem in using system()

[13sio]

hello,

i'm writing a interface by gtk+2.0 (a c based language) in linux. it's a window and have some buttons inside. when click a button, the program will call another software by system() command. if i do so, the interface window will halt. i wanna call another software and the window works normally.

thank you for your helping.

 

[newmangj]

The behaviour you observe is valid, the system() call doesn't return until the called application terminates.

You need to look at forking off a separate thread to do the work and examine it's return code when it finally completes. This allows your main GUI thread to continue to run.

You could fork off a new "worker" thread every time you need to run a system() command and have a reaping process to monitor the exit codes from these threads.

 

[13sio]

hi,

thx newmangj.

running the following code under RedHat 8.0,

----------------
#include <pthread.h>
#include <stdio.h>

void cb(void)
{
printf(&quot;%s&quot;, &quot;hi&quot;
}

int main (int argc, char *argv[])
{
pthread_t threads;
int rc;
rc = pthread_create(&threads, NULL, (void *)cb, NULL);
if (rc) {
printf(&quot;ERROR; return code from pthread_create() is %d\n&quot;, rc);
}
return 0;
}
----------------

there are statements as follows

/thread.o In function `main':
/thread.o(.text+0x3c): undefined reference to `pthread_create'
collect2: ld returned 1 exit status

 

[newmangj]

Are you linking the pthreads library? - try adding
-lpthread to you gcc command line

Cheers - Gavin

 

[13sio]

thx newmangj again. but i don't know how to add -lpthread in my makefile. the manual of gcc is hard to understand for me. here is my makefile.

------------
CC = gcc

app: window.o dialog.o callback.o simset.o filesel.o
$(CC) window.o dialog.o callback.o simset.o filesel.o -o app -lpthread `pkg-config --libs gtk+-2.0`

window.o: window.c dialog.h callback.h filesel.h
$(CC) -c window.c -o window.o `pkg-config gtk+-2.0 --cflags`

dialog.o: dialog.c dialog.h
$(CC) -c dialog.c -o dialog.o `pkg-config gtk+-2.0 --cflags`

callback.o: callback.c callback.h simset.h filesel.h
$(CC) -c callback.c -o callback.o -lpthread `pkg-config gtk+-2.0 --cflags`

simset.o: simset.c simset.h callback.h filesel.h
$(CC) -c simset.c -o simset.o `pkg-config gtk+-2.0 --cflags`

filesel.o: filesel.c filesel.h
$(CC) -c filesel.c -o filesel.o `pkg-config gtk+-2.0 --cflags`

clean:
rm -f *.o
------------

and the results are shown below.

gcc -c callback.c -o callback.o -lpthread `pkg-config gtk+-2.0 --cflags`
gcc: -lpthread: linker input file unused because linking not done
gcc -c simset.c -o simset.o `pkg-config gtk+-2.0 --cflags`
gcc -c filesel.c -o filesel.o `pkg-config gtk+-2.0 --cflags`
gcc window.o dialog.o callback.o simset.o filesel.o -o app -lpthread `pkg-config --libs gtk+-2.0`

another, sorry for the last question...it was raised and solved several days ago.