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wenjun1055wenjun1055
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study
1 parent 5284a2c commit 96f33a1

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6 files changed

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lines changed

6 files changed

+315
-0
lines changed

‎8.13.c

Lines changed: 77 additions & 0 deletions
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#include <stdio.h>
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#include <stdlib.h>
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#include <errno.h>
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#include <unistd.h>
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#include <sys/wait.h>
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int system(const char *cmdstring)
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{
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pid_t pid;
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int status;
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if (NULL == cmdstring) {
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return 1;
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}
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if ((pid = fork()) < 0) {
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status = -1;
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} else if (0 == pid) {
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execl("/bin", "sh", "-C", cmdstring, (char *)0);
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_exit(127);
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} else {
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while (waitpid(pid, &status, 0) < 0) {
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if (errno != EINTR) {
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status = -1;
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break;
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}
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}
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}
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return status;
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}
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void pr_exit(int status)
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{
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if (WIFEXITED(status)) {
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printf("normal termination, exit status = %d\n", WEXITSTATUS(status));
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} else if (WIFSIGNALED(status)) {
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printf("abnormal termination, signal number = %d%s\n",-
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WTERMSIG(status),
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#ifdef WCOREDUMP
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WCOREDUMP(status) ? " (core file generated)" : ""
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#else-
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""
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#endif
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);
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} else if (WIFSTOPPED(status)) {
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printf("child stopped, signal number = %d\n", WSTOPSIG(status));
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}
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}
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int main(void)
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{
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int status;
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if ((status = system("date")) < 0) {
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printf("system() error\n");
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exit(-1);
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}
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pr_exit(status);
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if ((status = system("nosuchcommand")) < 0) {
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printf("system() error\n");
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exit(-1);
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}
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pr_exit(status);
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if ((status = system("who; exit 44")) < 0) {
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printf("system() error\n");
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exit(-1);
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}
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pr_exit(status);
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return 0;
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}

‎8.18.c

Lines changed: 62 additions & 0 deletions
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#include <stdio.h>
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#include <stdlib.h>
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#include <unistd.h>
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#include <sys/times.h>
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static void pr_times(clock_t, struct tms *, struct tms *);
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static void do_cmd(char *);
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int main(int argc, char **argv)
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{
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int i;
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setbuf(stdout, NULL);
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for (i = 1; i < argc; i++) {
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//printf("%s\n", *(argv + i));
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do_cmd(*(argv + i));
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}
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return 0;
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}
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static void do_cmd(char *cmd)
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{
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struct tms tmsstart, tmsend;
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clock_t start, end;
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int status;
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printf("\ncommand: %s\n", cmd);
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if ((start = time(&tmsstart)) == -1) {
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printf("times error\n");
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exit(-1);
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}
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if ((status = system(cmd)) < 0) {
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printf("system() error\n");
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exit(-1);
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}
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if ((end = times(&tmsend)) == -1) {
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printf("times error\n");
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exit(-1);
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}
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pr_times(end - start, &tmsstart, &tmsend);
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}
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static void pr_times(clock_t real, struct tms *tmsstart, struct tms *tmsend)
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{
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static long clktck = 0;
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if (0 == clktck) {
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if (0 > (clktck = sysconf(_SC_CLK_TCK))) {
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printf("sysconf error\n");
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exit(-1);
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}
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}
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printf("\t real: %7.2f\n", real / (double) clktck);
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printf("\t user: %7.2f\n", (tmsend->tms_utime - tmsstart->tms_utime) / (double) clktck);
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printf("\t sys: %7.2f\n", (tmsend->tms_stime - tmsstart->tms_stime) / (double) clktck);
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printf("\t child user: %7.2f\n", (tmsend->tms_cutime - tmsstart->tms_cutime) / (double) clktck);
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printf("\t child sys: %7.2f\n", (tmsend->tms_cstime - tmsstart->tms_cstime) / (double) clktck);
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}

‎8.4.c

Lines changed: 73 additions & 0 deletions
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#include <stdio.h>
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#include <stdlib.h>
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#include <sys/wait.h>
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void pr_exit(int status)
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{
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if (WIFEXITED(status)) {
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printf("normal termination, exit status = %d\n", WEXITSTATUS(status));
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} else if (WIFSIGNALED(status)) {
10+
printf("abnormal termination, signal number = %d%s\n",
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WTERMSIG(status),
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#ifdef WCOREDUMP
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WCOREDUMP(status) ? " (core file generated)" : ""
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#else
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""
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#endif
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);
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} else if (WIFSTOPPED(status)) {
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printf("child stopped, signal number = %d\n", WSTOPSIG(status));
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}
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}
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int main(void)
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{
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pid_t pid;
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int status;
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if (0 > (pid = fork())) {
30+
printf("fork error\n");
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exit(-1);
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} else if (0 == pid) {
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exit(7);
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}
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if (pid != wait(&status)) {
37+
printf("wait error\n");
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exit(-1);
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}
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pr_exit(status);
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if (0 > (pid = fork())) {
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printf("fork error\n");
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exit(-1);
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} else if (0 == pid) {
47+
abort();
48+
}
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if (pid != wait(&status)) {
51+
printf("wait error\n");
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exit(-1);
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}
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pr_exit(status);
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if (0 > (pid = fork())) {
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printf("fork error\n");
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exit(-1);
61+
} else if (0 == pid) {
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status /= 0;
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}
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if (pid != wait(&status)) {
66+
printf("wait error\n");
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exit(-1);
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}
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pr_exit(status);
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return 0;
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}

‎8.5.c

Lines changed: 30 additions & 0 deletions
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#include <stdio.h>
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#include <stdlib.h>
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#include <sys/wait.h>
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int main(void)
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{
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pid_t pid;
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if (0 > (pid = fork())) {
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printf("fork error\n");
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exit(-1);
12+
} else if (0 == pid) {
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if (0 > (pid = fork())) {
14+
printf("fork error\n");
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exit(-1);
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} else if (pid > 0) {
17+
exit(0);
18+
}
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sleep(2);
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printf("second child, parent pid = %d\n", getppid());
22+
exit(0);
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}
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25+
if (pid != waitpid(pid, NULL, 0)) {
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printf("waitpid error\n");
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}
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exit(0);
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}

‎8.6.c

Lines changed: 31 additions & 0 deletions
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#include <stdio.h>
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#include <stdlib.h>
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static void charatatime(char *str)
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{
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char *ptr;
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int c;
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setbuf(stdout, NULL);
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for (ptr = str; (c = *ptr++) != 0;) {
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putc(c, stdout);
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}
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}
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int main(void)
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{
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pid_t pid;
20+
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if ((pid = fork()) < 0) {
22+
printf("fork error\n");
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exit(-1);
24+
} else if (0 == pid) {
25+
charatatime("output from child\n");
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} else {
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charatatime("output from parent\n");
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}
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return 0;
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}

‎apue.9.1.c

Lines changed: 42 additions & 0 deletions
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#include <stdio.h>
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#include <stdlib.h>
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#include <errno.h>
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#include <signal.h>
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#include <unistd.h>
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7+
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static void sig_hup(int signo)
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{
10+
printf("SIGHUP received, pid = %d\n", getpid());
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}
12+
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static void pr_ids(char *name)
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{
15+
printf("%s: pid = %d, ppid = %d, pgrd = %d, tpgrd = %d\n", name, getpid(), getppid(), getpgrp(), tcgetpgrp(STDIN_FILENO));
16+
fflush(stdout);
17+
}
18+
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int main(void)
20+
{
21+
char c;
22+
pid_t pid;
23+
24+
pr_ids("parent");
25+
if ((pid = fork()) < 0) {
26+
printf("fork error\n");
27+
exit(-1);
28+
} else if (pid > 0) {
29+
sleep(5);
30+
exit(0);
31+
} else {
32+
pr_ids("child");
33+
signal(SIGHUP, sig_hup);
34+
kill(getpid(), SIGTSTP);
35+
pr_ids("child");
36+
if (read(STDIN_FILENO, &c, 1) != 1 ) {
37+
printf("read error from controlling TTY, errno = %d\n", errno);
38+
}
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exit(0);
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}
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}

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