#挂载报错 [root@ yjc ~ ] # mount /dev/cdrom /mnt mount: no medium found on /dev/sr0 原因:设备文件是空的,里面没有任何内容,光驱没有连接
#卸载语法 umount 目标路径
#示例 [root@localhost ~]# umount /mnt
#卸载报错 [root@localhost mnt]# umount /mnt umount: /mnt: target is busy. (In some cases useful info about processes that use the device is found by lsof(8) or fuser(1)) [root@localhost mnt]# cd [root@localhost ~]# umount /mnt 原因:设备繁忙
#第一个端口 [root@localhost ~]# yum install -y python36-devel #第二个端口 [root@localhost ~]# yum remove -y tree Loaded plugins: fastestmirror Existing lock /var/run/yum.pid: another copy is running as pid 7387. Another app is currently holding the yum lock; waiting for it to exit... The other application is: yum Memory : 24 M RSS (419 MB VSZ) Started: Sat Apr 23 13:54:25 2022 - 00:05 ago State : Sleeping, pid: 7387 原因:另一个yum进程正在启动 #查看yum进程 [root@localhost ~]# /var/run/yum.pid 37494 #中止进程 [root@localhost ~]# kill 进程号
#显示Command line(一次性) [root@localhost ~]# yum --setopt=history_list_view=commands history list all ------------------------------------------------------------------------------- [root@localhost ~]# vim /etc/yum.conf # edit file "/etc/yum.conf" ==>>> and add this line somewhere in it history_list_view=cmds #查看yum的历史操作 [root@localhost ~]# yum history 命令的ID 执行的命令 执行的时间 动作 操作几个包 ID | Command line | Date and time | Action(s) | Altered ------------------------------------------------------------------------------- 55 | install -y tree | 2022-04-22 00:10 | Install | 1 54 | install -y yum-utils | 2022-04-21 23:44 | I, U | 5
#查看某个历史操作的详细信息 yum history info ID [root@localhost ~]# yum history info 46 [root@localhost ~]# yum history package-list tree
#撤销历史操作:一般撤销更新操作 [root@localhost ~]# yum history undo ID [root@localhost ~]# yum history undo 55