使用 strace 调试

ps -ef

示例输出:

root         440       1  0 00:00 ?        00:00:00 /usr/lib/system/systemd-udevd

strace -p 440

示例输出:

root@iq-9075-evk:/# strace -p 440
strace: Process 440 attached
gettid()                                = 440
epoll_pwait(7, [{events=EPOLLIN, data=0xb}], 212, -1, NULL, 8) = 1
read(11, "\1\0\0\0\0\0\0\0", 8)         = 8
socket(AF_UNIX, SOCK_DGRAM|SOCK_CLOEXEC, 0) = 15
getsockopt(15, SOL_SOCKET, SO_SNDBUF, [212992], [4]) = 0
setsockopt(15, SOL_SOCKET, SO_SNDBUF, [8388608], 4) = 0
getsockopt(15, SOL_SOCKET, SO_SNDBUF, [8388608], [4]) = 0
setsockopt(15, SOL_SOCKET, SO_SNDBUFFORCE, [8388608], 4) = 0
getuid()                                = 0
geteuid()                               = 0
getgid()                                = 0
getegid()                               = 0
sendmsg(15, {msg_name={sa_family=AF_UNIX, sun_path="/run/systemd/notify"}, msg_namelen=22, msg_iov=[{iov_base="WATCHDOG=1", iov_len=10}], msg_iovlen=1, msg_controllen=0, msg_flags=0}, MSG_NOSIGNAL) = 10
close(15)                               = 0
timerfd_settime(11, TFD_TIMER_ABSTIME, {it_interval={tv_sec=0, tv_nsec=0}, it_value={tv_sec=1490, tv_nsec=794546000}}, NULL) = 0
gettid()                                = 440
epoll_pwait(7