linux中ps命令

[root@centos7 ~]# ps -C nginx -o user,pid,comm
USER        PID COMMAND
root       2697 nginx
nginx      2698 nginx
nginx      2699 nginx
[root@centos7 ~]# ps aux|grep nginx
root       2697  0.0  0.1  45944  1136 ?        Ss   18:02   0:00 nginx: master process nginx
nginx      2698  0.0  0.1  48484  1980 ?        S    18:02   0:00 nginx: worker process
nginx      2699  0.0  0.1  48484  1980 ?        S    18:02   0:00 nginx: worker process
root       2702  0.0  0.0 112624   680 pts/0    R+   18:02   0:00 grep --color=auto nginx