ipc/popen_ls.c

   1 #include <stdio.h>
   2 #include <stdlib.h>
   3 #include <sys/wait.h>    /* for waitpid() macros */
   4
   5 #define MAX_STR 100
   6
   7 int main(void)
   8 {
   9     char str[MAX_STR];
  10     int ret;
  11     FILE *fp;
  12
  13     /* Initiate pipe stream to ls(1) */
  14     fp = popen("ls", "r");
  15     if (fp == NULL) {
  16         perror("popen()");
  17         exit(EXIT_FAILURE);
  18     }
  19
  20     /* Read from stream */
  21     while (fgets(str, MAX_STR, fp) != NULL)
  22         printf("%s", str);
  23
  24     /* Close pipe stream */
  25     ret = pclose(fp);
  26     if  (ret == -1) {
  27         perror("pclose()");
  28         exit(EXIT_FAILURE);
  29     }
  30     else {
  31         /*
  32          * Use macros described under wait() to inspect the return value
  33          * of pclose() in order to determine success/failure of command
  34          * executed by popen().
  35          */
  36
  37         if (WIFEXITED(ret)) {
  38             printf("Child exited, ret = %d\n", WEXITSTATUS(ret));
  39         } else if (WIFSIGNALED(ret)) {
  40             printf("Child killed, signal %d\n", WTERMSIG(ret));
  41         } else if (WIFSTOPPED(ret)) {
  42             printf("Child stopped, signal %d\n", WSTOPSIG(ret));
  43         }
  44         /* Not all implementations support this */
  45 #ifdef WIFCONTINUED
  46         else if (WIFCONTINUED(ret)) {
  47             printf("Child continued\n");
  48         }
  49 #endif
  50         /* Non standard case -- may never happen */
  51         else {
  52             printf("Unexpected return value, ret = 0x%x\n", ret);
  53         }
  54     }
  55
  56     return EXIT_SUCCESS;
  57 }