procexec/t_system.c

This is procexec/t_system.c (Listing 27-7, page 581), an example from the book, The Linux Programming Interface.

The source code file is copyright 2024, Michael Kerrisk, and is licensed under the GNU General Public License, version 3.

This page shows the "distribution" or "book" version of the file (why are there two versions?), or the differences between the two versions. You can switch between the views using the tabs below.

In the listing below, the names of Linux system calls and C library functions are hyperlinked to manual pages from the Linux man-pages project, and the names of functions implemented in the book are hyperlinked to the implementations of those functions.

  Cover of The Linux Programming Interface
+/* t_system.c
+
+   Demonstrate the use of system(3) to execute a shell command.
+*/
 #include <sys/wait.h>
 #include "print_wait_status.h"
 #include "tlpi_hdr.h"
 
 #define MAX_CMD_LEN 200
 
 int
 main(int argc, char *argv[])
 {
     char str[MAX_CMD_LEN];      /* Command to be executed by system() */
     int status;                 /* Status return from system() */
 
     for (;;) {                  /* Read and execute a shell command */
         printf("Command: ");
         fflush(stdout);
         if (fgets(str, MAX_CMD_LEN, stdin) == NULL)
             break;              /* end-of-file */
 
         status = system(str);
         printf("system() returned: status=0x%04x (%d,%d)\n",
                 (unsigned int) status, status >> 8, status & 0xff);
 
         if (status == -1) {
             errExit("system");
         } else {
             if (WIFEXITED(status) && WEXITSTATUS(status) == 127)
                 printf("(Probably) could not invoke shell\n");
             else                /* Shell successfully executed command */
                 printWaitStatus(NULL, status);
         }
     }
 
     exit(EXIT_SUCCESS);
 }

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