，安装strace
sudo apt-get install strace
2，查看php-fpm进程
vagrant@vagrant-ubuntu-precise-64:~$ ps -ef | grep php-fpm
root 2105 1 0 04:02 ? 00:00:02 php-fpm: master process (/etc/php5/fpm/php-fpm.conf)
www-data 2113 2105 0 04:02 ? 00:00:02 php-fpm: pool www
www-data 18481 2105 0 07:05 ? 00:00:01 php-fpm: pool www
www-data 18513 2105 0 07:06 ? 00:00:03 php-fpm: pool www
vagrant 19312 6379 0 10:14 pts/4 00:00:00 grep --color=auto php-fpm
3，调试进程输出日志到文件
vagrant@vagrant-ubuntu-precise-64:~$ sudo strace -f -p 2105 -e trace=file -o /temp/trace.log
Process 2105 attached - interrupt to quit
Process 19349 attached
Process 19350 attached
4，查看日志文件
tail -f /temp/trace.log
