How to import arguments to system() function

skie_knite007 · 03-24-2005, 11:47 PM

I need to create a iso fs using a C pgm. I can do it juz by calling system("mkisofs ---"); but how I can make it user interactive by providing arguments(variables) to this function

nixcraft · 03-25-2005, 12:33 AM

Try something as follows:

Code:

char s[100];
char cmd[200];

...
gets(s);
....
fprintf(cmd,"mkisofs %s",s);
...
system(cmd);

skie_knite007 · 03-25-2005, 06:35 AM

Thanx nixcraft,

But I 've got a problem.
A warning message like
" passing arg 1 of fprintf from incompatible pointer type " is displayed and the pgm problably is not working.
How to fix it out.

TheLinuxDuck · 03-25-2005, 08:05 AM

Actually, you'd want to use sprintf, not fprintf. fprintf is for printing to file handles/streams. Secondly, when getting user input, one should never use an input routine that does not restrict the # of chars the user is allowed to enter.

Code:

  char s[100];
  
  gets(s);  // WRONG
  fgets(s, 99, stdin); // RIGHT

And finally, don't use system. Use popen.

One reason for this is in the system man page:

Quote:

During execution of the command, SIGCHLD will be blocked, and SIGINT and SIGQUIT will be ignored.

nixcraft · 03-25-2005, 08:12 AM

Opps

it should be sprintf and not fprintf sorry...
here is the right one

Code:

#include<stdio.h>
main()
{
   char s[100];
   char cmd[200];
   printf("Enter arg : ");
   fgets(s,100,stdin);
   sprintf(cmd,"ls %s",s);
   system(cmd);
}

skie_knite007 · 03-25-2005, 08:49 PM

Thanx for u all,

It did really work