Device-to-time synchronization

#####################################
############## #设备 ###################
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1. Identification of equipment
/DEV/SDA # # #系统中的第一块串口硬盘
/dev/hda # # #系统中第一快并口硬盘
/DEV/HDB # # #系统中第二快并口硬盘
/dev/cdrom # # #系统光驱
/DEV/MAPPER/XXX # # #虚拟设备

2. Use of the device
Mount device Mount point # # #挂载
MOUNT/DEV/SDA1/MNT # # #把系统中的第一快硬盘的第一个分区挂载到/mnt
Umount Equipment | mount point # # #卸载设备
Blkid # # #显示所有可用设备的id信息
Df-h (2 of the N-square)-H (10 of N This party) # # # #查看挂载信息
Du-h (display unit)-s (only statistics directory itself) File|dir # # # #统计文件大小

3. When the following problem occurs when the device is uninstalled
[Email protected] ~]# umount/mnt/
Umount:/mnt:target is busy.
(In some cases useful info about processes
The device is found by lsof (8) or fuser (1))

Use
Fuser Equipment | mount point
Lsof Equipment | mount point
To find the process that consumes the device

4. How to find files in the system
Find command
Find path Condition Condition value
Find/mnt-name file
Find/mnt-name "file*"
Find/etc-name "*.conf"
-user # #用户
-group # #组
Condition 1-o Condition 2 # #或者
-type # #类型
-mmin +|-Number # #时间

DD If=/dev/zero of=/mnt/file bs=1024 count=10
DD # #数据截取
If # #数据模板
of # #数据存放文件
BS # #数据快大小
Count # #数据快个数

--size Numbers |-Digital |+ NUMBER # # #查找大小符合条件的文件

--perm 444 # # #文件全权必须时rrr
--perm-444 # # #文件每一位都要含有r权限
--perm/444 # # #文件任意一位含有r权限

-maxdepth Number # # #最深目录层
-mindepth Number # # #最小目录层
-exec command {} \; # # #对查找出的结果做相应处理

####### #locate #########
Locate + conditions # #在数据库中查找符合条件的文加
UpdateDB # #更新数据库

5. Links
###### #硬链接 #########
A hard link is a copy of the file in order to save the device node number
ln file links

##### #软链接 ############
Soft links When file shortcuts, in order to save device storage fast
Ln-s File Links

Ls-i # #查看一个文件节点号

Time synchronization
1. Service-side
Yum Install chrony-y chrony software
vim/etc/chrony.conf Editing a configuration file
Modify the 23 line allow IP (allows synchronized IP)
30 Row Uncomment
Exit Save
Systemctl Restart Chronyd.service
Systemctl Stop Firewalld

2 Client
vim/etc/chrony.conf Editing a configuration file
Delete Rows 3 to 6
Server IP iburst.
Exit Save
Systemctl Restart Chronyd.service

3. Testing
CHRONY.C sources-v

Device-to-time synchronization