A list of some of the problems of other #

1. centos7 and later modified hostname,  hostnamectl SEt- hostname centos7 
2. Before modifying hostname centos7,  VI / etc / sysconfig / Network; HOSTNAME = your_host_name 
3. linux mounted removable storage media,  Mount / dev / sdX_new / mnt / target_mount_point 
4. linux unload the mounted storage medium,  umount / dev / sdX_new # unloading equipment is, rather than mount point