signals/t_kill.c

This is signals/t_kill.c (Listing 20-3, page 405), an example from the book, The Linux Programming Interface.

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Cover of The Linux Programming Interface

+/* t_kill.c
+
+   Send a signal using kill(2) and analyze the return status of the call.
+*/
 #include <signal.h>
 #include "tlpi_hdr.h"
 
 int
 main(int argc, char *argv[])
 {
     int s, sig;
 
     if (argc != 3 || strcmp(argv[1], "--help") == 0)
         usageErr("%s pid sig-num\n", argv[0]);
 
     sig = getInt(argv[2], 0, "sig-num");
 
     s = kill(getLong(argv[1], 0, "pid"), sig);
 
     if (sig != 0) {
         if (s == -1)
             errExit("kill");
 
     } else {                    /* Null signal: process existence check */
         if (s == 0) {
             printf("Process exists and we can send it a signal\n");
         } else {
             if (errno == EPERM)
                 printf("Process exists, but we don't have "
                        "permission to send it a signal\n");
             else if (errno == ESRCH)
                 printf("Process does not exist\n");
             else
                 errExit("kill");
         }
     }
 
     exit(EXIT_SUCCESS);
 }

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