如何获取linux下的进程pid列表

用管道：
通过fgets(buf, n, ptr）buf就可以得到命令“ps -ef"一样的信息，
读帮助”man popen":

char *cmd = "ps -ef";

FILE *ptr;

if ((ptr = popen(cmd, "r")) != NULL)

while (fgets(buf, n, ptr) != NULL)

(void) printf("%s ",buf);

UID PID PPID C STIME TTY TIME CMD
root 0 0 0 Sep-30 ? 00:00:01 sched
root 1 0 0 Sep-30 ? 00:00:06 /etc/init -a
root 2 0 0 Sep-30 ? 00:00:00 vhand
root 3 0 0 Sep-30 ? 00:00:27 bdflush
root 4 0 0 Sep-30 ? 00:00:00 kmdaemon
root 5 1 0 Sep-30 ? 00:00:50 htepi_daemon /
root 6 0 0 Sep-30 ? 00:00:00 strd
root 2941 1 0 Oct-08 tty01 00:00:00 /bin/login ccb
root 43 1 0 Oct-08 ? 00:00:02 /etc/syslogd
root 47 1 0 Oct-08 ? 00:00:00 /etc/ifor_pmd
root 48 47 0 Oct-08 ? 00:00:13 /etc/ifor_pmd
root 36 1 0 Oct-08 ? 00:00:00

直接ps -fe就可以看到所有的进程PID信息了