Strace 的初步使用, 结合nginx

目录

• Strace 的初步使用, 结合nginx
  • 一，安装
  • 二，使用

Strace 的初步使用, 结合nginx

一，安装

sudo apt-get install strace

测试中可能用到的命令
ps -ef | grep nginx
ps -eo pid,ppid,sid,tty,pgrp,comm | grep -E 'bash|PID|nginx'

二，使用

我首先进入到nginx目录下

cwl@cwl-PC:/usr/local/nginx$ pwd
/usr/local/nginx
cwl@cwl-PC:/usr/local/nginx$ ls
client_body_temp  conf  fastcgi_temp  html  logs  proxy_temp  sbin  scgi_temp  uwsgi_temp

启动nginx

咱们启动nginx, 拉起了四个进程

cwl@cwl-PC:/usr/local/nginx/sbin$ sudo ./nginx 
cwl@cwl-PC:/usr/local/nginx/sbin$ ps -ef | grep nginx
root      9761     1  0 19:55 ?        00:00:00 nginx: master process ./nginx
nobody    9762  9761  0 19:55 ?        00:00:00 nginx: worker process
nobody    9763  9761  0 19:55 ?        00:00:00 nginx: worker process
nobody    9764  9761  0 19:55 ?        00:00:00 nginx: worker process
nobody    9765  9761  0 19:55 ?        00:00:00 nginx: worker process
cwl       9778 15969  0 19:56 pts/0    00:00:00 grep nginx

cwl@cwl-PC:/usr/local/nginx/sbin$ ps -eo pid,ppid,sid,tty,pgrp,comm | grep -E 'bash|PID|nginx'
  PID  PPID   SID TT        PGRP COMMAND
 9761     1  9761 ?         9761 nginx
 9762  9761  9761 ?         9761 nginx
 9763  9761  9761 ?         9761 nginx
 9764  9761  9761 ?         9761 nginx
 9765  9761  9761 ?         9761 nginx
11165 11135 11165 pts/2    11165 bash
15969 15947 15969 pts/0    15969 bash
16497 16476 16497 pts/1    16497 bash

strace追踪进程信号

命令格式

sudo strace -e trace=signal -p {pid}

终端一，贴上strace

cwl@cwl-PC:~$ sudo strace -e trace=signal -p 9761
[sudo] cwl 的密码：
strace: Process 9761 attached
rt_sigsuspend([], 8

终端二，断开nginx

cwl@cwl-PC:/usr/local/nginx/sbin$ sudo ./nginx -s quit

终端一，接收到信号

strace: Process 9761 attached
rt_sigsuspend([], 8)                    = ? ERESTARTNOHAND (To be restarted if no handler)
--- SIGQUIT {si_signo=SIGQUIT, si_code=SI_USER, si_pid=12201, si_uid=0} ---
rt_sigreturn({mask=[HUP INT QUIT USR1 USR2 ALRM TERM CHLD WINCH IO]}) = -1 EINTR (Interrupted system call)
rt_sigsuspend([], 8)                    = ? ERESTARTNOHAND (To be restarted if no handler)
--- SIGCHLD {si_signo=SIGCHLD, si_code=CLD_EXITED, si_pid=9762, si_uid=65534, si_status=0, si_utime=0, si_stime=0} ---
rt_sigreturn({mask=[HUP INT QUIT USR1 USR2 ALRM TERM CHLD WINCH IO]}) = -1 EINTR (Interrupted system call)
rt_sigsuspend([], 8)                    = ? ERESTARTNOHAND (To be restarted if no handler)
--- SIGIO {si_signo=SIGIO, si_code=SI_KERNEL} ---
rt_sigreturn({mask=[HUP INT QUIT USR1 USR2 ALRM TERM CHLD WINCH IO]}) = -1 EINTR (Interrupted system call)
rt_sigsuspend([], 8)                    = ? ERESTARTNOHAND (To be restarted if no handler)
--- SIGCHLD {si_signo=SIGCHLD, si_code=CLD_EXITED, si_pid=9763, si_uid=65534, si_status=0, si_utime=0, si_stime=0} ---
rt_sigreturn({mask=[HUP INT QUIT USR1 USR2 ALRM TERM CHLD WINCH IO]}) = -1 EINTR (Interrupted system call)
rt_sigsuspend([], 8)                    = ? ERESTARTNOHAND (To be restarted if no handler)
--- SIGCHLD {si_signo=SIGCHLD, si_code=CLD_EXITED, si_pid=9764, si_uid=65534, si_status=0, si_utime=0, si_stime=0} ---
--- SIGIO {si_signo=SIGIO, si_code=SI_KERNEL} ---
rt_sigreturn({mask=[CHLD]})             = 0
rt_sigreturn({mask=[HUP INT QUIT USR1 USR2 ALRM TERM CHLD WINCH IO]}) = -1 EINTR (Interrupted system call)
+++ exited with 0 +++

strace是一个最终信号的工具。扩展一下。如何关闭终端进程不退出呢？

方法：

• 拦截SIGHUP，而后本身处理
• 与bash进程不在同一个sesion中