diplodocus.org Git - nmh/blob - docs/historical/mh-jun-1982/Extras/libh/subshell.c

   1 #ifdef COMMENT
   2         Proprietary Rand Corporation, 1981.
   3         Further distribution of this software
   4         subject to the terms of the Rand
   5         license agreement.
   6 #endif
   7
   8 #include "../h/errors.h"
   9
  10 subshell(str)
  11 char *str;
  12 {
  13         register s2, s3;
  14         char *a2, *a3;
  15         register pid;
  16         char st[2];
  17         /* if str is non null, exec it as a command to the shell */
  18         /* and return immediately */
  19         /* if str is the null string, simply spawn a sub-shell */
  20
  21         if (str == 0 || *str == 0) {
  22                 a2 = 0;
  23                 a3 = 0;
  24         } else {
  25                 a2 = "-c";
  26                 a3 = str;
  27         }
  28         pid = fork();
  29         if (pid == 0) {
  30                 execl("/bin/sh", "-", a2, a3, 0);
  31                 error("no shell!");
  32         }
  33         if (pid == -1) {
  34                 type(2, errno == EAGAIN? "system": "your");
  35                 type(2, " process limit reached\n");
  36                 return(-1);
  37         }
  38         s2 = signal(2,1);
  39         s3 = signal(3,1);
  40         while(pid != wait(&st));
  41         signal(2,s2);
  42         signal(3,s3);
  43         return(st[1]);
  44 }