对已安装的包
which  systemctl
rpm -ql  /usr/bin/systemctl

对没有安装的包
rpm -qlp  net-tools-xxxx.x86_64.rpm   


# 对于没有安装的包，可以查询   已知"命令" ==>>  “对应的安装包”
yum provides  *systemctl
yum provides  *netstat

启用			禁用
enable    disable
enabled		disabled


[root@localhost ~]#systemctl enable  sshd
[root@localhost ~]#systemctl disable   sshd

cat  /etc/yum.repos.d/CentOS-Media.repo
cat  /etc/selinux/config  -n

history  | tail

rm  -rf /mnt/test/    #删除test目录
rm  -rf /mnt/test/*   # 清空test目录，保留test目录本身


yum  search  

find
cat   ifcfg-ens33  |grep yes
#粒度 颗粒度
grep -ir yes  .
grep -irl yes  .