procexec/t_system.c

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

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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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