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From: gt0178a@prism.gatech.EDU (BURNS)
Newsgroups: comp.unix.questions
Subject: Re: How to issue a C SHELL command with
Message-ID: <12585@hydra.gatech.EDU>
Date: 15 Aug 90 07:04:54 GMT
References: <22000008@ux1.cso.uiuc.edu>
Organization: Georgia Institute of Technology
Lines: 40

in article <22000008@ux1.cso.uiuc.edu>, kahlers@ux1.cso.uiuc.edu says:
  Nf-ID: #R:<25279:26:ux1.cso.uiuc.edu:22000008:000:429
  Nf-From: ux1.cso.uiuc.edu!kahlers    Aug 14 16:42:00 1990
>> How can I issue a statment that executes a C SHELL command within a C program?
>> I would appreciate any helps.
> 
> You can use the "system" call.  Use "man system" for more info.

The system call uses bourne sh, so this won't work unless the command you
pass to system is 'csh mycommand', which would be inefficient (sh calls
csh calls mycommand). Probably a skeleton like the following is needed:

#include <stdio.h>
#include <sys/wait.h>
char mycommand[] = "history";
main() {
   union wait status;
   int pid,some_status=1,some_other_status=2;
/*   char mycommand[10] = "history";*/

   fflush(0);             /* optional - check syntax on your system */
   switch (fork()) {
      case -1: perror();
	       exit(some_status);         /* fork failed */
	       break;
      case 0:                             /* child proc */
	       execlp("/bin/csh","csh","-c",mycommand,(char *) 0);
	       /* the -c is used when mycommand is a builtin */
	       exit(some_other_status);   /* exec failed */
	       break;
      default:            /* parent */
	       pid=wait(status);
	       break;
   }
}
-- 
BURNS,JIM
Georgia Institute of Technology, Box 30178, Atlanta Georgia, 30332
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