List of articles
- 1. Allow executable and non executable permissions
- 2.sync && async Synchronous write and asynchronous write
- 3.acl Use
- 4. Use UUID Mount
- 1） effect ： The command to mount the file system
- 2） The basic format is ：
- 3） Common file system types are ：
- 4） Check which operating systems are supported by the current system
- 5） Details of Mount options
- 6） And mount Related documents
- 7） And mount Related parameters
Hello everyone , I am Gao Shenghan , This article is about Linux Operation and maintenance - Step by step - The second part of the basic part 48 Original articles .
Let's talk today mount Use
Mount options -t File system type -o Options 1, Options 2…
mount -t ext4 -o acl /dev/sdb1 /mnt/
It doesn't matter if you can't understand it for the time being , We'll talk about it later .
at present centos7 The system of is XFS
About the above -t Parameters , We don't write a lot of time , however -t Parameter specifies the file system type, which is very important . We can check filesystems The configuration file , To see which file systems are supported by the current system
The second parameter in the above example -o
-o The mount options are specified later , There are many mount options
|rw||Reading and writing|
|dev||Support device files|
|nodev||Device files are not supported|
|noexec||Binary execution is not allowed|
|exec||Allow binary execution|
|auto||mount -a Power on auto mount|
|noauto||mount -a It doesn't mount automatically when the machine is turned on|
|noatime||Do not update access time atime|
|usrquota||Support user level disk quota function|
|grpquota||Support group level disk quota function|
|acl||Support acl function （ Access control list ）|
So in this example mount -t ext4 -o acl /dev/sdb1 /mnt/, -o hinder acl It supports access control lists .
Come here , I believe you can understand this example command , But understanding is just the beginning , Next , Let's talk about it in detail mount The past and this life .
- /etc/fstab ( Set up auto mount files ）
|-w||Reading and writing Default|
|-F||This order usually goes with -a Use it together , It will be for each mount The action of generating a journey is responsible for the execution of|
|-v||Show more information , Usually and -f Used to get rid of mistakes .|
|-L||Put the hard disk partition with a specific label on it .|
|-U||Divide the file into Our file system is down .-L and -U Must be in /proc/partition This kind of file is meaningful only when it exists .|
|-t||Specifies the type of the file system , It is usually not necessary to specify .mount The correct type will be selected automatically .|
|-a||take /etc/fstab All file systems defined in , This operation can realize the requirement of auto mount when starting up . When writing /etc/fstab After the document , The mount operation can also specify only the mount source or mount point|
[root@gaosh-1 ~]# ll /dev/sdb* Now there's a piece of sdb1 Disk brw-rw----. 1 root disk 8, 16 6 month 25 17:01 /dev/sdb brw-rw----. 1 root disk 8, 17 6 month 25 17:31 /dev/sdb1[root@gaosh-1 ~]#
Create two directories , A directory for mounting executable permissions , A directory for mounting non executable permissions
Mount and test ：
[root@gaosh-1 ~]# mount /dev/sdb1 /mnt/gexec Mount to executable binary Directory gexec[root@gaosh-1 ~]# cp -rf /bin/date /mnt/gexec # Copy a binary to test [root@gaosh-1 ~]# /mnt/gexec/date # Execute command discovery can be executed successfully 2020 year 06 month 25 Japan Thursday 21:13:51 CST[root@gaosh-1 ~]#
The above example proves that , After mounting, you can execute binary Directory , But there's no proof that if you add parameters noexec, You can't execute binary , Let's try
[root@gaosh-1 ~]# df -h Filesystem Size Used Avail Use% Mounted on /dev/sda2 20G 3.8G 15G 21% / tmpfs 1.8G 228K 1.8G 1% /dev/shm /dev/sda1 190M 40M 141M 22% /boot /dev/sdb1 4.9G 11M 4.6G 1% /mnt/gexec[root@gaosh-1 ~]# umount /mnt/gexec/ First unload it and mount it to another directory nexec[root@gaosh-1 ~]#
Next, we use a mount method that does not support executable permissions ,noexec, And test the
[root@gaosh-1 ~]# mount -o noexec /dev/sdb1 /mnt/nexec/ # Use here -o noexec Parameters
You can see , It's also copying past binaries , But when executing, it prompts that the permission is not enough .
[root@gaosh-1 ~]# mkdir /mnt/test1[root@gaosh-1 ~]# mount /dev/sdb1 /mnt/test1/[root@gaosh-1 ~]# mount/dev/sdb1 on /mnt/test1 type ext4 (rw)
Without parameters , The default is asynchronous write , You can see ,rw jurisdiction
[root@gaosh-1 test1]# time cp -rf /etc/ /mnt/test1 # Look at the write time real 0m0.112s user 0m0.000s sys 0m0.111s
If you add -o sync Let's take a look ：
[root@gaosh-1 ~]# umount /mnt/test1/ # Unload test1[root@gaosh-1 ~]# mkdir /mnt/test2 # establish test2 Catalog [root@gaosh-1 ~]# mount -o sync /dev/sdb1 /mnt/test2 Use sync Synchronous write mount /dev/sdb1 on /mnt/test2 type ext4 (rw,sync) # You can see rw, There are more synchronous writes in the back
[root@gaosh-1 ~]# time cp -rf /etc/ /mnt/test2 Look at the write time real 0m5.267s user 0m0.004s sys 0m1.322s
It's obvious that the synchronization time is longer ： Because when you synchronize client It takes time to get the response . But not in all cases is asynchrony faster than synchronization .
So here Shenghan means ： The speed of time is only valid in this experiment .
Set up auto mount
Check it out. , There is no mount at present ：
perform mount -a Automatically mount
[root@gaosh-1 ~]# mount/dev/sdb1 on /mnt/test1 type ext4 (rw,acl)
[root@gaosh-1 ~]# blkid /dev/sdb1/dev/sdb1: UUID="37c948a1-d0b9-49ff-923c-f3eac30eb0f3" TYPE="ext4"
Save and exit ： And then use mount -a
although mount There are many parameters for , But not every parameter needs to be mastered , Learn how to use /etc/fstab, Set up auto mount .
I am Gao Shenghan , A person who never forgets his original intention in the teaching and training industry , Welcome to my collection , See you next time ！
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