Table des matières
Last updated on: 2020/01/30 03:28
File Hierarchy System
The Linux filesystem hierarchy starts with the root represented by a / character. Under the root can be found other directories containing task specific files. The hierarchy conforms to a standard called the Linux File Hierarchy System.
Before proceeding further, using putty or a terminal on your host system, connect to your virtual machine using the trainee account with a password of trainee via localhost and one of the following ports :
- Debian 8: 2022
- SLES 12: 3022
- Ubuntu 16.04: 4022
- CentOS 7: 5022
For example, using a terminal on a Linux host :
$ ssh -l trainee -p 5022 localhost The authenticity of host '[localhost]:5022 ([127.0.0.1]:6022)' can't be established. ECDSA key fingerprint is SHA256:RgOsp/XI7JHNq+oIfHKw+jkHdtTnBIh+Dd7kVmHRxtU. Are you sure you want to continue connecting (yes/no)? yes Warning: Permanently added '[localhost]:5022' (ECDSA) to the list of known hosts. trainee@localhost's password: trainee
Using putty on a Windows™ host :
(Click on image to enlarge - note that this does not work in PDF version)
Click on the Accept button:
(Click on image to enlarge - note that this does not work in PDF version)
Login as trainee with password trainee :
(Click on image to enlarge - note that this does not work in PDF version)
Once connected, when using either CentOS 7, Debian 8 or SLES 12, enter the su - command, hit the ↵ Enter key and use the password fenestros. When using Ubuntu 16.04, enter the sudo su - command, hit the ↵ Enter key and use the password trainee. You are now connected as the root user.
Directory Contents
| Directory | Contents |
|---|---|
| /bin | Contains user programs such as ls, cp e.t.c.. Note that under RHEL 7 / CentOS7, this is a soft link (shorcut) to /usr/bin. |
| /boot | Contains bootloader files, kernels and initrd (INItial Ram Disk) files. |
| /dev | Contains nodes for accessing all the peripherals and devices connected to the system. The udev binary takes care of dynamically creating and deleting the relevant nodes automatically. |
| /etc | Contains static configuration files. |
| /home | Contains a directory for each registered user of the system except for root. |
| /lib | Contains common 32 bit libraries for applications and modules. Note that under RHEL 7 / CentOS7, this is a soft link (shorcut) to /usr/lib. |
| /lib64 | Contains common 64 bit libraries for applications and modules. Note that under RHEL 7 / CentOS7, this is a soft link (shorcut) to /usr/lib64. |
| /lost+found | Contains damaged file fragments found by the fsck command. |
| /media | Contains a folder for each of the mounted external file systems (CDRom DVDRom, USB Key e.t.c.). |
| /misc | RHEL 5, 6 and CentOS 5, 6 only. Contains mount points for local directories mounted via the automounter. |
| /mnt | Contains a folder for each external file system mounted temporarily by root. |
| /net | RHEL 5, 6 and CentOS 5, 6 only. Contains mount points for network directories mounted via the automounter. |
| /opt | Contains optional application packages. |
| /proc | Contains a virtual file system that documents kernel and process status information as text files. |
| /root | The home directory of the root user. |
| /run | Replaces the /var/run directory. Note that under RHEL 7 / CentOS7, Debian 7, Debian 8 and SLES 12, /var/run is a soft link (shorcut) to /run. |
| /sbin | Contains essential system administration binaires. Note that under RHEL 7 / CentOS7, this is a soft link (shorcut) to /usr/sbin. |
| /selinux | Contains a virtual file system used by SELINUX. |
| /snap | Ubuntu 16.04 only. Used in conjunction with the new Snap packages. |
| /srv | Contains site specific data served by the system (www,ftp,databases e.t.c.). |
| /sys | Contains a virtual file system that describes devices for udev. |
| /tmp | Contains the temporary files created by the system and by applications. |
| /usr | Contains user commands in /usr/bin, HOWTOs in /usr/share/doc, manuals in /usr/share/man and is the Secondary Hierarchy for read-only user data. |
| /var | Contains variable files. i.e. files that continually change such as log files and spool files. |
Directory Structure
Debian
trainee@debian6:/$ ls -l total 92 drwxr-xr-x 2 root root 4096 6 déc. 2014 bin drwxr-xr-x 3 root root 4096 6 déc. 2014 boot drwxr-xr-x 15 root root 3120 25 août 16:51 dev drwxr-xr-x 121 root root 12288 4 juil. 15:05 etc drwxr-xr-x 3 root root 4096 24 avril 2011 home lrwxrwxrwx 1 root root 28 24 avril 2011 initrd.img -> boot/initrd.img-2.6.32-5-686 drwxr-xr-x 12 root root 12288 6 déc. 2014 lib drwx------ 2 root root 16384 24 avril 2011 lost+found drwxr-xr-x 3 root root 4096 24 avril 2011 media drwxr-xr-x 2 root root 4096 14 déc. 2010 mnt drwxr-xr-x 4 root root 4096 4 déc. 2011 opt dr-xr-xr-x 128 root root 0 4 juil. 14:34 proc drwx------ 11 root root 4096 7 déc. 2014 root drwxr-xr-x 2 root root 4096 6 déc. 2014 sbin drwxr-xr-x 2 root root 4096 21 juil. 2010 selinux drwxr-xr-x 2 root root 4096 24 avril 2011 srv drwxr-xr-x 12 root root 0 4 juil. 14:34 sys drwxrwxrwt 10 root root 4096 25 août 16:34 tmp drwxr-xr-x 10 root root 4096 24 avril 2011 usr drwxr-xr-x 14 root root 4096 24 avril 2011 var lrwxrwxrwx 1 root root 25 24 avril 2011 vmlinuz -> boot/vmlinuz-2.6.32-5-686
trainee@debian7:/$ ls -l total 84 drwxr-xr-x 2 root root 4096 juin 26 16:06 bin drwxr-xr-x 3 root root 4096 juin 26 16:09 boot drwxr-xr-x 14 root root 3160 juil. 4 16:36 dev drwxr-xr-x 133 root root 12288 juil. 4 16:36 etc drwxr-xr-x 3 root root 4096 juin 26 15:42 home lrwxrwxrwx 1 root root 32 juin 26 15:35 initrd.img -> /boot/initrd.img-3.2.0-4-686-pae lrwxrwxrwx 1 root root 28 juin 26 15:35 initrd.img.old -> /boot/initrd.img-3.2.0-4-486 drwxr-xr-x 15 root root 4096 juin 26 16:01 lib drwx------ 2 root root 16384 juin 26 15:35 lost+found drwxr-xr-x 3 root root 4096 juil. 15 2014 media drwxr-xr-x 2 root root 4096 juil. 7 2014 mnt drwxr-xr-x 2 root root 4096 juil. 15 2014 opt dr-xr-xr-x 131 root root 0 juin 26 16:17 proc drwx------ 4 root root 4096 juil. 4 15:14 root drwxr-xr-x 20 root root 880 juil. 4 16:36 run drwxr-xr-x 2 root root 4096 juin 26 16:07 sbin drwxr-xr-x 2 root root 4096 juin 10 2012 selinux drwxr-xr-x 2 root root 4096 juil. 15 2014 srv drwxr-xr-x 13 root root 0 juin 26 16:17 sys drwxrwxrwt 9 root root 4096 juil. 4 16:17 tmp drwxr-xr-x 10 root root 4096 juin 26 15:39 usr drwxr-xr-x 12 root root 4096 juin 26 15:39 var lrwxrwxrwx 1 root root 28 juin 26 15:39 vmlinuz -> boot/vmlinuz-3.2.0-4-686-pae lrwxrwxrwx 1 root root 24 juin 26 15:39 vmlinuz.old -> boot/vmlinuz-3.2.0-4-486
trainee@debian8:/$ ls -l total 84 drwxr-xr-x 2 root root 4096 juin 28 16:31 bin drwxr-xr-x 3 root root 4096 juin 28 16:31 boot drwxr-xr-x 17 root root 3080 juil. 23 17:04 dev drwxr-xr-x 125 root root 12288 août 27 12:18 etc drwxr-xr-x 3 root root 4096 juin 28 16:30 home lrwxrwxrwx 1 root root 33 juin 28 16:26 initrd.img -> /boot/initrd.img-3.16.0-4-686-pae lrwxrwxrwx 1 root root 29 juin 28 16:26 initrd.img.old -> /boot/initrd.img-3.16.0-4-586 drwxr-xr-x 18 root root 4096 juin 28 16:31 lib drwxr-xr-x 2 root root 4096 juin 6 17:07 live-build drwx------ 2 root root 16384 juin 28 16:26 lost+found drwxr-xr-x 3 root root 4096 juin 6 16:32 media drwxr-xr-x 2 root root 4096 juin 6 16:32 mnt drwxr-xr-x 3 root root 4096 juin 28 16:38 opt dr-xr-xr-x 138 root root 0 juin 28 16:41 proc drwx------ 2 root root 4096 juin 28 16:35 root drwxr-xr-x 24 root root 820 août 27 12:18 run drwxr-xr-x 2 root root 4096 juin 28 16:39 sbin drwxr-xr-x 2 root root 4096 juin 6 16:32 srv dr-xr-xr-x 13 root root 0 juin 28 16:41 sys drwxrwxrwt 12 root root 4096 juil. 23 16:17 tmp drwxr-xr-x 10 root root 4096 juin 28 16:29 usr drwxr-xr-x 11 root root 4096 juin 28 16:29 var lrwxrwxrwx 1 root root 29 juin 28 16:29 vmlinuz -> boot/vmlinuz-3.16.0-4-686-pae lrwxrwxrwx 1 root root 25 juin 28 16:29 vmlinuz.old -> boot/vmlinuz-3.16.0-4-586
Ubuntu
trainee@ubuntu1404:/$ ls -l total 92 drwxr-xr-x 2 root root 4096 sept. 27 2014 bin drwxr-xr-x 3 root root 4096 sept. 27 2014 boot drwxrwxr-x 2 root root 4096 sept. 27 2014 cdrom drwxr-xr-x 15 root root 4120 sept. 25 15:17 dev drwxr-xr-x 131 root root 12288 sept. 25 15:17 etc drwxr-xr-x 3 root root 4096 sept. 27 2014 home lrwxrwxrwx 1 root root 33 sept. 27 2014 initrd.img -> boot/initrd.img-3.13.0-32-generic drwxr-xr-x 23 root root 4096 sept. 27 2014 lib drwx------ 2 root root 16384 sept. 27 2014 lost+found drwxr-xr-x 3 root root 4096 sept. 28 2014 media drwxr-xr-x 2 root root 4096 avril 11 2014 mnt drwxr-xr-x 3 root root 4096 sept. 28 2014 opt dr-xr-xr-x 102 root root 0 sept. 25 15:17 proc drwx------ 2 root root 4096 oct. 14 2014 root drwxr-xr-x 20 root root 700 sept. 25 15:17 run drwxr-xr-x 2 root root 12288 sept. 28 2014 sbin drwxr-xr-x 2 root root 4096 juil. 22 2014 srv dr-xr-xr-x 13 root root 0 sept. 25 15:17 sys drwxrwxrwt 4 root root 4096 sept. 25 15:17 tmp drwxr-xr-x 10 root root 4096 juil. 22 2014 usr drwxr-xr-x 13 root root 4096 juil. 23 2014 var lrwxrwxrwx 1 root root 30 sept. 27 2014 vmlinuz -> boot/vmlinuz-3.13.0-32-generic
trainee@ubuntu1604:/$ ls -l total 100 drwxr-xr-x 2 root root 4096 mai 3 07:47 bin drwxr-xr-x 3 root root 4096 mai 3 07:49 boot drwxrwxr-x 2 root root 4096 mai 3 07:25 cdrom drwxr-xr-x 19 root root 4180 août 18 12:39 dev drwxr-xr-x 129 root root 12288 sept. 25 11:12 etc drwxr-xr-x 3 root root 4096 mai 3 07:27 home lrwxrwxrwx 1 root root 32 mai 3 07:31 initrd.img -> boot/initrd.img-4.4.0-21-generic drwxr-xr-x 22 root root 4096 mai 3 07:47 lib drwxr-xr-x 2 root root 4096 avril 21 00:07 lib64 drwx------ 2 root root 16384 mai 3 07:17 lost+found drwxr-xr-x 2 root root 4096 avril 21 00:07 media drwxr-xr-x 2 root root 4096 avril 21 00:07 mnt drwxr-xr-x 3 root root 4096 mai 3 08:14 opt dr-xr-xr-x 114 root root 0 août 18 12:39 proc drwx------ 4 root root 4096 mai 3 08:33 root drwxr-xr-x 24 root root 820 sept. 25 11:40 run drwxr-xr-x 2 root root 12288 mai 3 07:51 sbin drwxr-xr-x 2 root root 4096 avril 19 16:31 snap drwxr-xr-x 2 root root 4096 avril 21 00:07 srv dr-xr-xr-x 13 root root 0 août 18 12:38 sys drwxrwxrwt 9 root root 4096 sept. 25 11:17 tmp drwxr-xr-x 11 root root 4096 avril 21 00:13 usr drwxr-xr-x 14 root root 4096 avril 21 00:19 var lrwxrwxrwx 1 root root 29 mai 3 07:31 vmlinuz -> boot/vmlinuz-4.4.0-21-generic
Red Hat Enterprise Linux (RHEL)/CentOS
[trainee@centos5 /]$ ls -l total 138 drwxr-xr-x 2 root root 4096 août 25 13:27 bin drwxr-xr-x 4 root root 1024 août 25 14:03 boot drwxr-xr-x 11 root root 3800 août 25 14:06 dev drwxr-xr-x 102 root root 12288 août 25 14:06 etc drwxr-xr-x 3 root root 4096 août 25 13:36 home drwxr-xr-x 14 root root 4096 août 25 13:42 lib drwx------ 2 root root 16384 août 25 13:16 lost+found drwxr-xr-x 3 root root 4096 août 25 14:06 media drwxr-xr-x 2 root root 0 août 25 14:06 misc drwxr-xr-x 2 root root 4096 mai 11 2011 mnt drwxr-xr-x 2 root root 0 août 25 14:06 net drwxr-xr-x 4 root root 4096 août 25 13:44 opt dr-xr-xr-x 143 root root 0 août 25 14:05 proc drwxr-x--- 4 root root 4096 août 25 14:01 root drwxr-xr-x 2 root root 12288 août 25 14:03 sbin drwxr-xr-x 4 root root 0 août 25 14:05 selinux drwxr-xr-x 2 root root 4096 mai 11 2011 srv drwxr-xr-x 11 root root 0 août 25 14:05 sys drwxrwxrwt 14 root root 4096 août 25 14:09 tmp drwxr-xr-x 14 root root 4096 août 25 13:23 usr drwxr-xr-x 21 root root 4096 août 25 13:31 var
[trainee@centos6 /]$ ls -l total 98 dr-xr-xr-x. 2 root root 4096 9 août 12:52 bin dr-xr-xr-x. 5 root root 1024 7 déc. 2014 boot drwxr-xr-x. 19 root root 3820 25 août 11:29 dev drwxr-xr-x. 119 root root 12288 25 août 11:28 etc drwxr-xr-x. 3 root root 4096 3 mai 2013 home dr-xr-xr-x. 20 root root 12288 9 août 12:52 lib drwx------. 2 root root 16384 3 mai 2013 lost+found drwxr-xr-x. 2 root root 4096 7 déc. 2014 media drwxr-xr-x. 2 root root 0 25 août 11:28 misc drwxr-xr-x. 3 root root 4096 5 juil. 12:22 mnt drwxr-xr-x. 2 root root 0 25 août 11:28 net drwxr-xr-x. 6 root root 4096 7 déc. 2014 opt dr-xr-xr-x. 154 root root 0 25 août 11:27 proc dr-xr-x---. 10 root root 4096 9 août 12:58 root dr-xr-xr-x. 2 root root 12288 9 août 12:52 sbin drwxr-xr-x. 7 root root 0 25 août 11:27 selinux drwxr-xr-x. 2 root root 4096 23 sept. 2011 srv drwxr-xr-x. 13 root root 0 25 août 11:27 sys drwxrwxrwt. 16 root root 4096 25 août 11:30 tmp drwxr-xr-x. 13 root root 4096 3 mai 2013 usr drwxr-xr-x. 22 root root 4096 9 août 12:50 var
[trainee@centos7 /]$ ls -l total 32 lrwxrwxrwx. 1 root root 7 Mar 8 13:41 bin -> usr/bin dr-xr-xr-x. 4 root root 4096 Jun 4 15:00 boot drwxr-xr-x. 19 root root 3280 Jul 7 15:55 dev drwxr-xr-x. 131 root root 8192 Jul 23 17:05 etc drwxr-xr-x. 4 root root 47 Jul 5 14:11 home lrwxrwxrwx. 1 root root 7 Mar 8 13:41 lib -> usr/lib lrwxrwxrwx. 1 root root 9 Mar 8 13:41 lib64 -> usr/lib64 drwxr-xr-x. 2 root root 6 Jun 10 2014 media drwxr-xr-x. 3 root root 18 Jul 5 13:57 mnt drwxr-xr-x. 4 root root 47 Jun 4 09:36 opt dr-xr-xr-x. 177 root root 0 Jul 7 15:53 proc dr-xr-x---. 5 root root 4096 Aug 25 11:31 root drwxr-xr-x. 35 root root 1100 Jul 23 15:40 run lrwxrwxrwx. 1 root root 8 Mar 8 13:41 sbin -> usr/sbin drwxr-xr-x. 2 root root 6 Jun 10 2014 srv dr-xr-xr-x. 13 root root 0 Jul 7 15:53 sys drwxrwxrwt. 25 root root 4096 Jul 23 15:40 tmp drwxr-xr-x. 13 root root 4096 Mar 8 13:41 usr drwxr-xr-x. 22 root root 4096 Jul 7 15:53 var
SUSE Linux Enterprise Server (SLES)
trainee@SLES11SP1:/> ls -l total 101 drwxr-xr-x 2 root root 4096 25 sept. 15:48 bin drwxr-xr-x 4 root root 1024 25 sept. 17:08 boot drwxr-xr-x 16 root root 4020 25 sept. 17:08 dev drwxr-xr-x 88 root root 12288 25 sept. 17:14 etc drwxr-xr-x 3 root root 4096 25 sept. 15:55 home drwxr-xr-x 13 root root 4096 25 sept. 15:49 lib drwxr-xr-x 8 root root 12288 25 sept. 15:48 lib64 drwx------ 2 root root 16384 25 sept. 15:43 lost+found drwxr-xr-x 2 root root 4096 5 mai 2010 media drwxr-xr-x 2 root root 4096 5 mai 2010 mnt drwxr-xr-x 2 root root 4096 5 mai 2010 opt dr-xr-xr-x 88 root root 0 25 sept. 17:07 proc drwx------ 6 root root 4096 25 sept. 17:14 root drwxr-xr-x 3 root root 12288 25 sept. 15:50 sbin drwxr-xr-x 2 root root 4096 5 mai 2010 selinux drwxr-xr-x 4 root root 4096 25 sept. 15:43 srv drwxr-xr-x 12 root root 0 25 sept. 17:07 sys drwxrwxrwt 4 root root 4096 25 sept. 17:22 tmp drwxr-xr-x 13 root root 4096 25 sept. 15:43 usr drwxr-xr-x 15 root root 4096 25 sept. 15:44 var
trainee@SLES12SP1:/> ls -l total 0 drwxr-xr-x 1 root root 1810 20 sept. 13:33 bin drwxr-xr-x 1 root root 1096 21 sept. 04:19 boot drwxr-xr-x 16 root root 3620 21 sept. 04:18 dev drwxr-xr-x 1 root root 4746 21 sept. 04:18 etc drwxr-xr-x 1 root root 14 20 sept. 13:34 home drwxr-xr-x 1 root root 2906 20 sept. 13:32 lib drwxr-xr-x 1 root root 4998 20 sept. 13:31 lib64 drwxr-xr-x 1 root root 0 21 sept. 2014 mnt drwxr-xr-x 1 root root 0 21 sept. 2014 opt dr-xr-xr-x 100 root root 0 20 sept. 13:47 proc drwx------ 1 root root 112 20 sept. 14:00 root drwxr-xr-x 25 root root 640 21 sept. 04:18 run drwxr-xr-x 1 root root 5044 20 sept. 13:33 sbin drwxr-xr-x 1 root root 0 21 sept. 2014 selinux drwxr-xr-x 1 root root 12 20 sept. 13:29 srv dr-xr-xr-x 12 root root 0 20 sept. 13:47 sys drwxrwxrwt 1 root root 102 21 sept. 04:18 tmp drwxr-xr-x 1 root root 130 20 sept. 13:29 usr drwxr-xr-x 1 root root 108 20 sept. 13:33 var
File Types
The three major file types under Linux are :
- Ordinary files,
- Directories,
- Special files or Devices.
Note that :
- Ordinary files can be anything from text files to binaries.
- The length of a file name is limited to 225 characters, including the file extension.
- Linux is case sensitive.
- If a file name starts with a dot (.), it is a hidden file.
The mount command
In order to be able to use external file systems, such as a CDRom or DVDRom, Linux needs to be informed of their availability. This is accomplished by using the mount command:
# mount /dev/<special_file> /mnt/<directory_name> [Enter]
where /dev/<special_file> is the file system to mount and /mnt/<directory_name> is the target directory where the mounted file system will be available to the system. The directory /mnt/<directory_name> must exist prior to using the mount command.
In the case where the mount command is used without options, the current mounted file systems are shown:
Debian
root@debian6:~# mount /dev/sda1 on / type ext3 (rw,errors=remount-ro) tmpfs on /lib/init/rw type tmpfs (rw,nosuid,mode=0755) proc on /proc type proc (rw,noexec,nosuid,nodev) sysfs on /sys type sysfs (rw,noexec,nosuid,nodev) udev on /dev type tmpfs (rw,mode=0755) tmpfs on /dev/shm type tmpfs (rw,nosuid,nodev) devpts on /dev/pts type devpts (rw,noexec,nosuid,gid=5,mode=620) fusectl on /sys/fs/fuse/connections type fusectl (rw) binfmt_misc on /proc/sys/fs/binfmt_misc type binfmt_misc (rw,noexec,nosuid,nodev)
root@debian7:~# mount sysfs on /sys type sysfs (rw,nosuid,nodev,noexec,relatime) proc on /proc type proc (rw,nosuid,nodev,noexec,relatime) udev on /dev type devtmpfs (rw,relatime,size=10240k,nr_inodes=127976,mode=755) devpts on /dev/pts type devpts (rw,nosuid,noexec,relatime,gid=5,mode=620,ptmxmode=000) tmpfs on /run type tmpfs (rw,nosuid,noexec,relatime,size=103420k,mode=755) /dev/disk/by-uuid/0f1cdb0c-8bd7-45ec-8d99-064292047bdb on / type ext4 (rw,relatime,errors=remount-ro,user_xattr,barrier=1,data=ordered) tmpfs on /run/lock type tmpfs (rw,nosuid,nodev,noexec,relatime,size=5120k) tmpfs on /run/shm type tmpfs (rw,nosuid,nodev,noexec,relatime,size=597180k) rpc_pipefs on /var/lib/nfs/rpc_pipefs type rpc_pipefs (rw,relatime) binfmt_misc on /proc/sys/fs/binfmt_misc type binfmt_misc (rw,nosuid,nodev,noexec,relatime)
root@debian8:~# mount sysfs on /sys type sysfs (rw,nosuid,nodev,noexec,relatime) proc on /proc type proc (rw,nosuid,nodev,noexec,relatime) udev on /dev type devtmpfs (rw,relatime,size=10240k,nr_inodes=126281,mode=755) devpts on /dev/pts type devpts (rw,nosuid,noexec,relatime,gid=5,mode=620,ptmxmode=000) tmpfs on /run type tmpfs (rw,nosuid,relatime,size=206376k,mode=755) /dev/sda1 on / type ext4 (rw,relatime,errors=remount-ro,data=ordered) securityfs on /sys/kernel/security type securityfs (rw,nosuid,nodev,noexec,relatime) tmpfs on /dev/shm type tmpfs (rw,nosuid,nodev) tmpfs on /run/lock type tmpfs (rw,nosuid,nodev,noexec,relatime,size=5120k) tmpfs on /sys/fs/cgroup type tmpfs (ro,nosuid,nodev,noexec,mode=755) cgroup on /sys/fs/cgroup/systemd type cgroup (rw,nosuid,nodev,noexec,relatime,xattr,release_agent=/lib/systemd/systemd-cgroups-agent,name=systemd) pstore on /sys/fs/pstore type pstore (rw,nosuid,nodev,noexec,relatime) cgroup on /sys/fs/cgroup/cpuset type cgroup (rw,nosuid,nodev,noexec,relatime,cpuset) cgroup on /sys/fs/cgroup/cpu,cpuacct type cgroup (rw,nosuid,nodev,noexec,relatime,cpu,cpuacct) cgroup on /sys/fs/cgroup/devices type cgroup (rw,nosuid,nodev,noexec,relatime,devices) cgroup on /sys/fs/cgroup/freezer type cgroup (rw,nosuid,nodev,noexec,relatime,freezer) cgroup on /sys/fs/cgroup/net_cls,net_prio type cgroup (rw,nosuid,nodev,noexec,relatime,net_cls,net_prio) cgroup on /sys/fs/cgroup/blkio type cgroup (rw,nosuid,nodev,noexec,relatime,blkio) cgroup on /sys/fs/cgroup/perf_event type cgroup (rw,nosuid,nodev,noexec,relatime,perf_event) tmpfs on /etc/machine-id type tmpfs (ro,relatime,size=206376k,mode=755) systemd-1 on /proc/sys/fs/binfmt_misc type autofs (rw,relatime,fd=22,pgrp=1,timeout=300,minproto=5,maxproto=5,direct) hugetlbfs on /dev/hugepages type hugetlbfs (rw,relatime) mqueue on /dev/mqueue type mqueue (rw,relatime) debugfs on /sys/kernel/debug type debugfs (rw,relatime) fusectl on /sys/fs/fuse/connections type fusectl (rw,relatime) rpc_pipefs on /run/rpc_pipefs type rpc_pipefs (rw,relatime) tmpfs on /run/user/119 type tmpfs (rw,nosuid,nodev,relatime,size=103188k,mode=700,uid=119,gid=127) tmpfs on /run/user/1000 type tmpfs (rw,nosuid,nodev,relatime,size=103188k,mode=700,uid=1000,gid=1000)
Ubuntu
trainee@ubuntu1404:/$ mount /dev/sda1 on / type ext4 (rw,errors=remount-ro) proc on /proc type proc (rw,noexec,nosuid,nodev) sysfs on /sys type sysfs (rw,noexec,nosuid,nodev) none on /sys/fs/cgroup type tmpfs (rw) none on /sys/fs/fuse/connections type fusectl (rw) none on /sys/kernel/debug type debugfs (rw) none on /sys/kernel/security type securityfs (rw) udev on /dev type devtmpfs (rw,mode=0755) devpts on /dev/pts type devpts (rw,noexec,nosuid,gid=5,mode=0620) tmpfs on /run type tmpfs (rw,noexec,nosuid,size=10%,mode=0755) none on /run/lock type tmpfs (rw,noexec,nosuid,nodev,size=5242880) none on /run/shm type tmpfs (rw,nosuid,nodev) none on /run/user type tmpfs (rw,noexec,nosuid,nodev,size=104857600,mode=0755) none on /sys/fs/pstore type pstore (rw) systemd on /sys/fs/cgroup/systemd type cgroup (rw,noexec,nosuid,nodev,none,name=systemd)
root@ubuntu1604:~# mount sysfs on /sys type sysfs (rw,nosuid,nodev,noexec,relatime) proc on /proc type proc (rw,nosuid,nodev,noexec,relatime) udev on /dev type devtmpfs (rw,nosuid,relatime,size=230832k,nr_inodes=57708,mode=755) devpts on /dev/pts type devpts (rw,nosuid,noexec,relatime,gid=5,mode=620,ptmxmode=000) tmpfs on /run type tmpfs (rw,nosuid,noexec,relatime,size=50028k,mode=755) /dev/sda1 on / type ext4 (rw,relatime,errors=remount-ro,data=ordered) securityfs on /sys/kernel/security type securityfs (rw,nosuid,nodev,noexec,relatime) tmpfs on /dev/shm type tmpfs (rw,nosuid,nodev) tmpfs on /run/lock type tmpfs (rw,nosuid,nodev,noexec,relatime,size=5120k) tmpfs on /sys/fs/cgroup type tmpfs (ro,nosuid,nodev,noexec,mode=755) cgroup on /sys/fs/cgroup/systemd type cgroup (rw,nosuid,nodev,noexec,relatime,xattr,release_agent=/lib/systemd/systemd-cgroups-agent,name=systemd,nsroot=/) pstore on /sys/fs/pstore type pstore (rw,nosuid,nodev,noexec,relatime) cgroup on /sys/fs/cgroup/hugetlb type cgroup (rw,nosuid,nodev,noexec,relatime,hugetlb,nsroot=/) cgroup on /sys/fs/cgroup/memory type cgroup (rw,nosuid,nodev,noexec,relatime,memory,nsroot=/) cgroup on /sys/fs/cgroup/freezer type cgroup (rw,nosuid,nodev,noexec,relatime,freezer,nsroot=/) cgroup on /sys/fs/cgroup/cpuset type cgroup (rw,nosuid,nodev,noexec,relatime,cpuset,nsroot=/) cgroup on /sys/fs/cgroup/pids type cgroup (rw,nosuid,nodev,noexec,relatime,pids,nsroot=/) cgroup on /sys/fs/cgroup/blkio type cgroup (rw,nosuid,nodev,noexec,relatime,blkio,nsroot=/) cgroup on /sys/fs/cgroup/net_cls,net_prio type cgroup (rw,nosuid,nodev,noexec,relatime,net_cls,net_prio,nsroot=/) cgroup on /sys/fs/cgroup/perf_event type cgroup (rw,nosuid,nodev,noexec,relatime,perf_event,nsroot=/) cgroup on /sys/fs/cgroup/devices type cgroup (rw,nosuid,nodev,noexec,relatime,devices,nsroot=/) cgroup on /sys/fs/cgroup/cpu,cpuacct type cgroup (rw,nosuid,nodev,noexec,relatime,cpu,cpuacct,nsroot=/) systemd-1 on /proc/sys/fs/binfmt_misc type autofs (rw,relatime,fd=22,pgrp=1,timeout=0,minproto=5,maxproto=5,direct) mqueue on /dev/mqueue type mqueue (rw,relatime) debugfs on /sys/kernel/debug type debugfs (rw,relatime) hugetlbfs on /dev/hugepages type hugetlbfs (rw,relatime) fusectl on /sys/fs/fuse/connections type fusectl (rw,relatime) tmpfs on /run/user/1000 type tmpfs (rw,nosuid,nodev,relatime,size=50028k,mode=700,uid=1000,gid=1000)
RHEL/CentOS
[root@centos5 ~]# mount /dev/sda2 on / type ext3 (rw) proc on /proc type proc (rw) sysfs on /sys type sysfs (rw) devpts on /dev/pts type devpts (rw,gid=5,mode=620) /dev/sda1 on /boot type ext3 (rw) tmpfs on /dev/shm type tmpfs (rw) none on /proc/sys/fs/binfmt_misc type binfmt_misc (rw) sunrpc on /var/lib/nfs/rpc_pipefs type rpc_pipefs (rw)
[root@centos6 /]# mount /dev/sda2 on / type ext4 (rw) proc on /proc type proc (rw) sysfs on /sys type sysfs (rw) devpts on /dev/pts type devpts (rw,gid=5,mode=620) tmpfs on /dev/shm type tmpfs (rw) /dev/sda1 on /boot type ext3 (rw) none on /proc/sys/fs/binfmt_misc type binfmt_misc (rw) sunrpc on /var/lib/nfs/rpc_pipefs type rpc_pipefs (rw)
[root@centos7 ~]# mount proc on /proc type proc (rw,nosuid,nodev,noexec,relatime) sysfs on /sys type sysfs (rw,nosuid,nodev,noexec,relatime,seclabel) devtmpfs on /dev type devtmpfs (rw,nosuid,seclabel,size=1449668k,nr_inodes=362417,mode=755) securityfs on /sys/kernel/security type securityfs (rw,nosuid,nodev,noexec,relatime) tmpfs on /dev/shm type tmpfs (rw,nosuid,nodev,seclabel) devpts on /dev/pts type devpts (rw,nosuid,noexec,relatime,seclabel,gid=5,mode=620,ptmxmode=000) tmpfs on /run type tmpfs (rw,nosuid,nodev,seclabel,mode=755) tmpfs on /sys/fs/cgroup type tmpfs (rw,nosuid,nodev,noexec,seclabel,mode=755) cgroup on /sys/fs/cgroup/systemd type cgroup (rw,nosuid,nodev,noexec,relatime,xattr,release_agent=/usr/lib/systemd/systemd-cgroups-agent,name=systemd) pstore on /sys/fs/pstore type pstore (rw,nosuid,nodev,noexec,relatime) cgroup on /sys/fs/cgroup/cpuset type cgroup (rw,nosuid,nodev,noexec,relatime,cpuset) cgroup on /sys/fs/cgroup/cpu,cpuacct type cgroup (rw,nosuid,nodev,noexec,relatime,cpuacct,cpu) cgroup on /sys/fs/cgroup/memory type cgroup (rw,nosuid,nodev,noexec,relatime,memory) cgroup on /sys/fs/cgroup/devices type cgroup (rw,nosuid,nodev,noexec,relatime,devices) cgroup on /sys/fs/cgroup/freezer type cgroup (rw,nosuid,nodev,noexec,relatime,freezer) cgroup on /sys/fs/cgroup/net_cls type cgroup (rw,nosuid,nodev,noexec,relatime,net_cls) cgroup on /sys/fs/cgroup/blkio type cgroup (rw,nosuid,nodev,noexec,relatime,blkio) cgroup on /sys/fs/cgroup/perf_event type cgroup (rw,nosuid,nodev,noexec,relatime,perf_event) cgroup on /sys/fs/cgroup/hugetlb type cgroup (rw,nosuid,nodev,noexec,relatime,hugetlb) configfs on /sys/kernel/config type configfs (rw,relatime) /dev/sda2 on / type xfs (rw,relatime,seclabel,attr2,inode64,noquota) selinuxfs on /sys/fs/selinux type selinuxfs (rw,relatime) systemd-1 on /proc/sys/fs/binfmt_misc type autofs (rw,relatime,fd=32,pgrp=1,timeout=300,minproto=5,maxproto=5,direct) debugfs on /sys/kernel/debug type debugfs (rw,relatime) hugetlbfs on /dev/hugepages type hugetlbfs (rw,relatime,seclabel) mqueue on /dev/mqueue type mqueue (rw,relatime,seclabel) sunrpc on /var/lib/nfs/rpc_pipefs type rpc_pipefs (rw,relatime) nfsd on /proc/fs/nfsd type nfsd (rw,relatime) /dev/sda1 on /boot type xfs (rw,relatime,seclabel,attr2,inode64,noquota) fusectl on /sys/fs/fuse/connections type fusectl (rw,relatime) gvfsd-fuse on /run/user/1000/gvfs type fuse.gvfsd-fuse (rw,nosuid,nodev,relatime,user_id=1000,group_id=1000)
SLES
SLES11SP1:~ # mount /dev/sda2 on / type ext3 (rw,acl,user_xattr) proc on /proc type proc (rw) sysfs on /sys type sysfs (rw) debugfs on /sys/kernel/debug type debugfs (rw) udev on /dev type tmpfs (rw,mode=0755) tmpfs on /dev/shm type tmpfs (rw,mode=1777) devpts on /dev/pts type devpts (rw,mode=0620,gid=5) /dev/sda1 on /boot type ext3 (rw,acl,user_xattr) fusectl on /sys/fs/fuse/connections type fusectl (rw) securityfs on /sys/kernel/security type securityfs (rw)
SLES12SP1:~ # mount sysfs on /sys type sysfs (rw,nosuid,nodev,noexec,relatime) proc on /proc type proc (rw,nosuid,nodev,noexec,relatime) devtmpfs on /dev type devtmpfs (rw,nosuid,size=1931968k,nr_inodes=482992,mode=755) securityfs on /sys/kernel/security type securityfs (rw,nosuid,nodev,noexec,relatime) tmpfs on /dev/shm type tmpfs (rw,nosuid,nodev) devpts on /dev/pts type devpts (rw,nosuid,noexec,relatime,gid=5,mode=620,ptmxmode=000) tmpfs on /run type tmpfs (rw,nosuid,nodev,mode=755) tmpfs on /sys/fs/cgroup type tmpfs (rw,nosuid,nodev,noexec,mode=755) cgroup on /sys/fs/cgroup/systemd type cgroup (rw,nosuid,nodev,noexec,relatime,xattr,release_agent=/usr/lib/systemd/systemd-cgroups-agent,name=systemd) pstore on /sys/fs/pstore type pstore (rw,nosuid,nodev,noexec,relatime) cgroup on /sys/fs/cgroup/cpuset type cgroup (rw,nosuid,nodev,noexec,relatime,cpuset) cgroup on /sys/fs/cgroup/cpu,cpuacct type cgroup (rw,nosuid,nodev,noexec,relatime,cpuacct,cpu) cgroup on /sys/fs/cgroup/memory type cgroup (rw,nosuid,nodev,noexec,relatime,memory) cgroup on /sys/fs/cgroup/devices type cgroup (rw,nosuid,nodev,noexec,relatime,devices) cgroup on /sys/fs/cgroup/freezer type cgroup (rw,nosuid,nodev,noexec,relatime,freezer) cgroup on /sys/fs/cgroup/blkio type cgroup (rw,nosuid,nodev,noexec,relatime,blkio) cgroup on /sys/fs/cgroup/perf_event type cgroup (rw,nosuid,nodev,noexec,relatime,perf_event) cgroup on /sys/fs/cgroup/hugetlb type cgroup (rw,nosuid,nodev,noexec,relatime,hugetlb) /dev/sda2 on / type btrfs (rw,relatime,space_cache,subvolid=259,subvol=/@/.snapshots/1/snapshot) systemd-1 on /proc/sys/fs/binfmt_misc type autofs (rw,relatime,fd=31,pgrp=1,timeout=300,minproto=5,maxproto=5,direct) mqueue on /dev/mqueue type mqueue (rw,relatime) debugfs on /sys/kernel/debug type debugfs (rw,relatime) hugetlbfs on /dev/hugepages type hugetlbfs (rw,relatime) /dev/sda2 on /.snapshots type btrfs (rw,relatime,space_cache,subvolid=258,subvol=/@/.snapshots) /dev/sda2 on /var/lib/mailman type btrfs (rw,relatime,space_cache,subvolid=269,subvol=/@/var/lib/mailman) /dev/sda2 on /var/lib/mariadb type btrfs (rw,relatime,space_cache,subvolid=270,subvol=/@/var/lib/mariadb) /dev/sda2 on /var/log type btrfs (rw,relatime,space_cache,subvolid=274,subvol=/@/var/log) /dev/sda2 on /tmp type btrfs (rw,relatime,space_cache,subvolid=265,subvol=/@/tmp) /dev/sda2 on /var/spool type btrfs (rw,relatime,space_cache,subvolid=276,subvol=/@/var/spool) /dev/sda2 on /var/lib/named type btrfs (rw,relatime,space_cache,subvolid=272,subvol=/@/var/lib/named) /dev/sda2 on /srv type btrfs (rw,relatime,space_cache,subvolid=264,subvol=/@/srv) /dev/sda2 on /usr/local type btrfs (rw,relatime,space_cache,subvolid=266,subvol=/@/usr/local) /dev/sda2 on /var/opt type btrfs (rw,relatime,space_cache,subvolid=275,subvol=/@/var/opt) /dev/sda2 on /var/lib/pgsql type btrfs (rw,relatime,space_cache,subvolid=273,subvol=/@/var/lib/pgsql) /dev/sda2 on /opt type btrfs (rw,relatime,space_cache,subvolid=263,subvol=/@/opt) /dev/sda2 on /var/tmp type btrfs (rw,relatime,space_cache,subvolid=277,subvol=/@/var/tmp) /dev/sda2 on /var/lib/mysql type btrfs (rw,relatime,space_cache,subvolid=271,subvol=/@/var/lib/mysql) /dev/sda2 on /var/lib/libvirt/images type btrfs (rw,relatime,space_cache,subvolid=268,subvol=/@/var/lib/libvirt/images) /dev/sda2 on /var/crash type btrfs (rw,relatime,space_cache,subvolid=267,subvol=/@/var/crash) /dev/sda2 on /home type btrfs (rw,relatime,space_cache,subvolid=262,subvol=/@/home) /dev/sda2 on /boot/grub2/x86_64-efi type btrfs (rw,relatime,space_cache,subvolid=261,subvol=/@/boot/grub2/x86_64-efi) /dev/sda2 on /boot/grub2/i386-pc type btrfs (rw,relatime,space_cache,subvolid=260,subvol=/@/boot/grub2/i386-pc)
Important : Note that under RHEL 5 / CentOS 5, Debian 6 and SLES 11, the default filesystem is ext3, under RHEL 6 / CentOS 6, Debian 7, Debian 8, Ubuntu 14.04 and Ubuntu 16.04, the default filesystem is ext4, under RHEL 7 / CentOS the default filesystem is xfs whilst under SLES 12, the default filesystem is btrfs. Please see the unit Managing Disks, Swap Space and Filesystems for further coursework concerning ext3, ext4, xfs and btrfs filesystems.
Command Line Switches
The following switches can be used with the mount command:
root@debian8:~# mount --help
Usage:
mount [-lhV]
mount -a [options]
mount [options] [--source] <source> | [--target] <directory>
mount [options] <source> <directory>
mount <operation> <mountpoint> [<target>]
Options:
-a, --all mount all filesystems mentioned in fstab
-c, --no-canonicalize don't canonicalize paths
-f, --fake dry run; skip the mount(2) syscall
-F, --fork fork off for each device (use with -a)
-T, --fstab <path> alternative file to /etc/fstab
-h, --help display this help text and exit
-i, --internal-only don't call the mount.<type> helpers
-l, --show-labels lists all mounts with LABELs
-n, --no-mtab don't write to /etc/mtab
-o, --options <list> comma-separated list of mount options
-O, --test-opts <list> limit the set of filesystems (use with -a)
-r, --read-only mount the filesystem read-only (same as -o ro)
-t, --types <list> limit the set of filesystem types
--source <src> explicitly specifies source (path, label, uuid)
--target <target> explicitly specifies mountpoint
-v, --verbose say what is being done
-V, --version display version information and exit
-w, --rw, --read-write mount the filesystem read-write (default)
-h, --help display this help and exit
-V, --version output version information and exit
Source:
-L, --label <label> synonym for LABEL=<label>
-U, --uuid <uuid> synonym for UUID=<uuid>
LABEL=<label> specifies device by filesystem label
UUID=<uuid> specifies device by filesystem UUID
PARTLABEL=<label> specifies device by partition label
PARTUUID=<uuid> specifies device by partition UUID
<device> specifies device by path
<directory> mountpoint for bind mounts (see --bind/rbind)
<file> regular file for loopdev setup
Operations:
-B, --bind mount a subtree somewhere else (same as -o bind)
-M, --move move a subtree to some other place
-R, --rbind mount a subtree and all submounts somewhere else
--make-shared mark a subtree as shared
--make-slave mark a subtree as slave
--make-private mark a subtree as private
--make-unbindable mark a subtree as unbindable
--make-rshared recursively mark a whole subtree as shared
--make-rslave recursively mark a whole subtree as slave
--make-rprivate recursively mark a whole subtree as private
--make-runbindable recursively mark a whole subtree as unbindable
For more details see mount(8).
root@ubuntu1604:~# mount --help
Usage:
mount [-lhV]
mount -a [options]
mount [options] [--source] <source> | [--target] <directory>
mount [options] <source> <directory>
mount <operation> <mountpoint> [<target>]
Mount a filesystem.
Options:
-a, --all mount all filesystems mentioned in fstab
-c, --no-canonicalize don't canonicalize paths
-f, --fake dry run; skip the mount(2) syscall
-F, --fork fork off for each device (use with -a)
-T, --fstab <path> alternative file to /etc/fstab
-i, --internal-only don't call the mount.<type> helpers
-l, --show-labels show also filesystem labels
-n, --no-mtab don't write to /etc/mtab
-o, --options <list> comma-separated list of mount options
-O, --test-opts <list> limit the set of filesystems (use with -a)
-r, --read-only mount the filesystem read-only (same as -o ro)
-t, --types <list> limit the set of filesystem types
--source <src> explicitly specifies source (path, label, uuid)
--target <target> explicitly specifies mountpoint
-v, --verbose say what is being done
-w, --rw, --read-write mount the filesystem read-write (default)
-h, --help display this help and exit
-V, --version output version information and exit
Source:
-L, --label <label> synonym for LABEL=<label>
-U, --uuid <uuid> synonym for UUID=<uuid>
LABEL=<label> specifies device by filesystem label
UUID=<uuid> specifies device by filesystem UUID
PARTLABEL=<label> specifies device by partition label
PARTUUID=<uuid> specifies device by partition UUID
<device> specifies device by path
<directory> mountpoint for bind mounts (see --bind/rbind)
<file> regular file for loopdev setup
Operations:
-B, --bind mount a subtree somewhere else (same as -o bind)
-M, --move move a subtree to some other place
-R, --rbind mount a subtree and all submounts somewhere else
--make-shared mark a subtree as shared
--make-slave mark a subtree as slave
--make-private mark a subtree as private
--make-unbindable mark a subtree as unbindable
--make-rshared recursively mark a whole subtree as shared
--make-rslave recursively mark a whole subtree as slave
--make-rprivate recursively mark a whole subtree as private
--make-runbindable recursively mark a whole subtree as unbindable
For more details see mount(8).
[root@centos7 ~]# mount --help
Usage:
mount [-lhV]
mount -a [options]
mount [options] [--source] <source> | [--target] <directory>
mount [options] <source> <directory>
mount <operation> <mountpoint> [<target>]
Options:
-a, --all mount all filesystems mentioned in fstab
-c, --no-canonicalize don't canonicalize paths
-f, --fake dry run; skip the mount(2) syscall
-F, --fork fork off for each device (use with -a)
-T, --fstab <path> alternative file to /etc/fstab
-h, --help display this help text and exit
-i, --internal-only don't call the mount.<type> helpers
-l, --show-labels lists all mounts with LABELs
-n, --no-mtab don't write to /etc/mtab
-o, --options <list> comma-separated list of mount options
-O, --test-opts <list> limit the set of filesystems (use with -a)
-r, --read-only mount the filesystem read-only (same as -o ro)
-t, --types <list> limit the set of filesystem types
--source <src> explicitly specifies source (path, label, uuid)
--target <target> explicitly specifies mountpoint
-v, --verbose say what is being done
-V, --version display version information and exit
-w, --rw, --read-write mount the filesystem read-write (default)
-h, --help display this help and exit
-V, --version output version information and exit
Source:
-L, --label <label> synonym for LABEL=<label>
-U, --uuid <uuid> synonym for UUID=<uuid>
LABEL=<label> specifies device by filesystem label
UUID=<uuid> specifies device by filesystem UUID
PARTLABEL=<label> specifies device by partition label
PARTUUID=<uuid> specifies device by partition UUID
<device> specifies device by path
<directory> mountpoint for bind mounts (see --bind/rbind)
<file> regular file for loopdev setup
Operations:
-B, --bind mount a subtree somewhere else (same as -o bind)
-M, --move move a subtree to some other place
-R, --rbind mount a subtree and all submounts somewhere else
--make-shared mark a subtree as shared
--make-slave mark a subtree as slave
--make-private mark a subtree as private
--make-unbindable mark a subtree as unbindable
--make-rshared recursively mark a whole subtree as shared
--make-rslave recursively mark a whole subtree as slave
--make-rprivate recursively mark a whole subtree as private
--make-runbindable recursively mark a whole subtree as unbindable
For more details see mount(8).
SLES12SP1:~ # mount --help
Usage:
mount [-lhV]
mount -a [options]
mount [options] [--source] <source> | [--target] <directory>
mount [options] <source> <directory>
mount <operation> <mountpoint> [<target>]
Options:
-a, --all mount all filesystems mentioned in fstab
-c, --no-canonicalize don't canonicalize paths
-f, --fake dry run; skip the mount(2) syscall
-F, --fork fork off for each device (use with -a)
-T, --fstab <path> alternative file to /etc/fstab
-h, --help display this help text and exit
-i, --internal-only don't call the mount.<type> helpers
-l, --show-labels lists all mounts with LABELs
-n, --no-mtab don't write to /etc/mtab
-o, --options <list> comma-separated list of mount options
-O, --test-opts <list> limit the set of filesystems (use with -a)
-r, --read-only mount the filesystem read-only (same as -o ro)
-t, --types <list> limit the set of filesystem types
--source <src> explicitly specifies source (path, label, uuid)
--target <target> explicitly specifies mountpoint
-v, --verbose say what is being done
-V, --version display version information and exit
-w, --rw, --read-write mount the filesystem read-write (default)
-h, --help display this help and exit
-V, --version output version information and exit
Source:
-L, --label <label> synonym for LABEL=<label>
-U, --uuid <uuid> synonym for UUID=<uuid>
LABEL=<label> specifies device by filesystem label
UUID=<uuid> specifies device by filesystem UUID
PARTLABEL=<label> specifies device by partition label
PARTUUID=<uuid> specifies device by partition UUID
<device> specifies device by path
<directory> mountpoint for bind mounts (see --bind/rbind)
<file> regular file for loopdev setup
Operations:
-B, --bind mount a subtree somewhere else (same as -o bind)
-M, --move move a subtree to some other place
-R, --rbind mount a subtree and all submounts somewhere else
--make-shared mark a subtree as shared
--make-slave mark a subtree as slave
--make-private mark a subtree as private
--make-unbindable mark a subtree as unbindable
--make-rshared recursively mark a whole subtree as shared
--make-rslave recursively mark a whole subtree as slave
--make-rprivate recursively mark a whole subtree as private
--make-runbindable recursively mark a whole subtree as unbindable
For more details see mount(8).
The /etc/fstab file
In the case where the mount command is used with the -a option, all mount points specified in the /etc/fstab file are mounted:
Debian
root@debian6:~# cat /etc/fstab # /etc/fstab: static file system information. # # Use 'blkid' to print the universally unique identifier for a # device; this may be used with UUID= as a more robust way to name devices # that works even if disks are added and removed. See fstab(5). # # <file system> <mount point> <type> <options> <dump> <pass> proc /proc proc defaults 0 0 # / was on /dev/sda1 during installation UUID=a42a1ddd-14bc-4dde-a537-e6c1b984a782 / ext3 errors=remount-ro 0 1 # swap was on /dev/sda5 during installation UUID=e21d8931-21ca-4ab3-9fbb-bd71657b312e none swap sw 0 0
root@debian7:~# cat /etc/fstab # /etc/fstab: static file system information. # # Use 'blkid' to print the universally unique identifier for a # device; this may be used with UUID= as a more robust way to name devices # that works even if disks are added and removed. See fstab(5). # # <file system> <mount point> <type> <options> <dump> <pass> # / was on /dev/sda1 during installation UUID=0f1cdb0c-8bd7-45ec-8d99-064292047bdb / ext4 errors=remount-ro 0 1 # swap was on /dev/sda5 during installation UUID=ae5f67d1-6fad-487e-ad41-d53992a75755 none swap sw 0 0
root@debian8:~# cat /etc/fstab # /etc/fstab: static file system information. # # Use 'blkid' to print the universally unique identifier for a # device; this may be used with UUID= as a more robust way to name devices # that works even if disks are added and removed. See fstab(5). # # <file system> <mount point> <type> <options> <dump> <pass> # / was on /dev/sda1 during installation UUID=0ac29bda-b6bb-41c2-b47a-03fecb95bc87 / ext4 errors=remount-ro 0 1 # swap was on /dev/sda5 during installation UUID=fa3153a5-5ef4-46fe-9115-d3773a06d283 none swap sw 0 0
Ubuntu
root@ubuntu1404:~# cat /etc/fstab # /etc/fstab: static file system information. # # Use 'blkid' to print the universally unique identifier for a # device; this may be used with UUID= as a more robust way to name devices # that works even if disks are added and removed. See fstab(5). # # <file system> <mount point> <type> <options> <dump> <pass> # / was on /dev/sda1 during installation UUID=70eb8bc5-1759-433d-9797-9342a7b82cb2 / ext4 errors=remount-ro 0 1 # swap was on /dev/sda5 during installation UUID=85017f2f-081d-464e-ad83-52c3c895a113 none swap sw 0 0
root@ubuntu1604:~# cat /etc/fstab # /etc/fstab: static file system information. # # Use 'blkid' to print the universally unique identifier for a # device; this may be used with UUID= as a more robust way to name devices # that works even if disks are added and removed. See fstab(5). # # <file system> <mount point> <type> <options> <dump> <pass> # / was on /dev/sda1 during installation UUID=c27fce7f-cc8a-4c6f-b19b-d929a4d570f2 / ext4 errors=remount-ro 0 1 # swap was on /dev/sda5 during installation UUID=68f67549-63f1-4833-b792-3566455bbe95 none swap sw 0 0
[root@centos5 ~]# cat /etc/fstab LABEL=/ / ext3 defaults 1 1 LABEL=/boot /boot ext3 defaults 1 2 tmpfs /dev/shm tmpfs defaults 0 0 devpts /dev/pts devpts gid=5,mode=620 0 0 sysfs /sys sysfs defaults 0 0 proc /proc proc defaults 0 0 LABEL=SWAP-sda3 swap swap defaults 0 0
RHEL/CentOS
[root@centos6 ~]# cat /etc/fstab # # /etc/fstab # Created by anaconda on Fri May 3 13:33:42 2013 # # Accessible filesystems, by reference, are maintained under '/dev/disk' # See man pages fstab(5), findfs(8), mount(8) and/or blkid(8) for more info # UUID=b9f29672-c84e-4d3b-b132-189758a084eb / ext4 defaults 1 1 UUID=01baf03d-df0d-479b-b3e4-81ce63b8dec3 /boot ext4 defaults 1 2 UUID=2646a33a-65f3-4501-9ced-9459435fd774 swap swap defaults 0 0 tmpfs /dev/shm tmpfs defaults 0 0 devpts /dev/pts devpts gid=5,mode=620 0 0 sysfs /sys sysfs defaults 0 0 proc /proc proc defaults 0 0
[root@centos7 ~]# cat /etc/fstab # # /etc/fstab # Created by anaconda on Sun Mar 8 12:38:10 2015 # # Accessible filesystems, by reference, are maintained under '/dev/disk' # See man pages fstab(5), findfs(8), mount(8) and/or blkid(8) for more info # UUID=b35de665-5ec8-4226-a533-58a1b567ac91 / xfs defaults 1 1 UUID=e8d3bd48-1386-411c-9675-41c3f8f1a309 /boot xfs defaults 1 2 UUID=11a4d11d-81e4-46a7-82e0-7796cd597dc9 swap swap defaults 0 0
SLES
SLES11SP1:~ # cat /etc/fstab /dev/disk/by-id/ata-VBOX_HARDDISK_VB62af9a29-d9a982d5-part3 swap swap defaults 0 0 /dev/disk/by-id/ata-VBOX_HARDDISK_VB62af9a29-d9a982d5-part2 / ext3 acl,user_xattr 1 1 /dev/disk/by-id/ata-VBOX_HARDDISK_VB62af9a29-d9a982d5-part1 /boot ext3 acl,user_xattr 1 2 proc /proc proc defaults 0 0 sysfs /sys sysfs noauto 0 0 debugfs /sys/kernel/debug debugfs noauto 0 0 usbfs /proc/bus/usb usbfs noauto 0 0 devpts /dev/pts devpts mode=0620,gid=5 0 0
SLES12SP1:~ # cat /etc/fstab UUID=db743358-c2d6-47f6-97d7-e7a9c650f0c5 swap swap defaults 0 0 UUID=6b7e374a-ae42-4f93-b6aa-d288dfbbb74b / btrfs defaults 0 0 UUID=6b7e374a-ae42-4f93-b6aa-d288dfbbb74b /boot/grub2/i386-pc btrfs subvol=@/boot/grub2/i386-pc 0 0 UUID=6b7e374a-ae42-4f93-b6aa-d288dfbbb74b /boot/grub2/x86_64-efi btrfs subvol=@/boot/grub2/x86_64-efi 0 0 UUID=6b7e374a-ae42-4f93-b6aa-d288dfbbb74b /home btrfs subvol=@/home 0 0 UUID=6b7e374a-ae42-4f93-b6aa-d288dfbbb74b /opt btrfs subvol=@/opt 0 0 UUID=6b7e374a-ae42-4f93-b6aa-d288dfbbb74b /srv btrfs subvol=@/srv 0 0 UUID=6b7e374a-ae42-4f93-b6aa-d288dfbbb74b /tmp btrfs subvol=@/tmp 0 0 UUID=6b7e374a-ae42-4f93-b6aa-d288dfbbb74b /usr/local btrfs subvol=@/usr/local 0 0 UUID=6b7e374a-ae42-4f93-b6aa-d288dfbbb74b /var/crash btrfs subvol=@/var/crash 0 0 UUID=6b7e374a-ae42-4f93-b6aa-d288dfbbb74b /var/lib/libvirt/images btrfs subvol=@/var/lib/libvirt/images 0 0 UUID=6b7e374a-ae42-4f93-b6aa-d288dfbbb74b /var/lib/mailman btrfs subvol=@/var/lib/mailman 0 0 UUID=6b7e374a-ae42-4f93-b6aa-d288dfbbb74b /var/lib/mariadb btrfs subvol=@/var/lib/mariadb 0 0 UUID=6b7e374a-ae42-4f93-b6aa-d288dfbbb74b /var/lib/mysql btrfs subvol=@/var/lib/mysql 0 0 UUID=6b7e374a-ae42-4f93-b6aa-d288dfbbb74b /var/lib/named btrfs subvol=@/var/lib/named 0 0 UUID=6b7e374a-ae42-4f93-b6aa-d288dfbbb74b /var/lib/pgsql btrfs subvol=@/var/lib/pgsql 0 0 UUID=6b7e374a-ae42-4f93-b6aa-d288dfbbb74b /var/log btrfs subvol=@/var/log 0 0 UUID=6b7e374a-ae42-4f93-b6aa-d288dfbbb74b /var/opt btrfs subvol=@/var/opt 0 0 UUID=6b7e374a-ae42-4f93-b6aa-d288dfbbb74b /var/spool btrfs subvol=@/var/spool 0 0 UUID=6b7e374a-ae42-4f93-b6aa-d288dfbbb74b /var/tmp btrfs subvol=@/var/tmp 0 0 UUID=6b7e374a-ae42-4f93-b6aa-d288dfbbb74b /.snapshots btrfs subvol=@/.snapshots 0 0
Understanding the /etc/fstab file
Each line in /etc/fstab has 6 fields :
| Field 1 | Field 2 | Field 3 | Field 4 | Field 5 | Field 6 |
|---|---|---|---|---|---|
| Special file or UUID or Virtual File System | Mount Point | Filesystem Type | Comma separated list of options | Used by the dump command ( 1 = dump, 0 or empty = do not dump ) | The order in which the fsck command checks the disks/partitions at boot time |
The UUID ( Universally Unique Identifier ) is a randomly generated 128 bit string that is automatically generated by the system when a filesystem is created on the partition.
Mountpoint Options
The most important mount point options are as follows:
| Option | Filesystem | Description | Default Value |
|---|---|---|---|
| defaults | All | Use default options: rw, suid, dev, exec, auto, nouser, and async. | N/A 1) |
| auto/noauto | All | Do or do not mount when “mount -a” is given. | auto |
| rw/ro | All | Mount the filesystem read-write/read-only. | rw |
| suid/nosuid | All | Allow/disallow set-user-identifier or set-group-identifier bits to take effect. | suid |
| dev/nodev | All | Interpret/do not interpret character or block special devices on the filesystem. | dev |
| exec/noexec | All | Permit/do not permit execution of binaries. | exec |
| sync/async | All | All I/O to the filesystem should be done synchronously/asynchronously. | async |
| user/nouser | All | Allow/disallow a user to mount. The mount point is read from the /etc/fstab file. Only the user that mounted the filesystem can unmount it. | N/A |
| users | All | Allow every user to mount and unmount the filesystem. | N/A |
| owner | All | Allow device owner to mount. | N/A |
| atime/noatime | POSIX | Do not use noatime feature, then the inode access time is controlled by kernel defaults/Do not update inode access times on this filesystem | atime |
| uid=value | Non-Linux filesystems | Set the owner of the root of the filesystem. | root |
| gid=value | Non-Linux filesystems | Set the group of the root of the filesystem. | N/A |
| umask=value | Non-Linux filesystems | Set the umask. The default is the umask of the current process. The value is given in octal. | N/A |
| dmask=value | Non-Linux filesystems | Set the umask applied to directories only. The value is given in octal. | Current processes' umask |
| fmask=value | Non-Linux filesystems | Set the umask applied to regular files only. The value is given in octal. | Current processes' umask |
The umount command
To unmount a file system, you need to use the umount command. For example:
# umount /mnt/target_directory [Entrée]
Command Line Switches
The following switches can be used with the umount command:
trainee@debian8:~$ umount --help
Usage:
umount [-hV]
umount -a [options]
umount [options] <source> | <directory>
Options:
-a, --all unmount all filesystems
-A, --all-targets unmount all mountpoints for the given device in the
current namespace
-c, --no-canonicalize don't canonicalize paths
-d, --detach-loop if mounted loop device, also free this loop device
--fake dry run; skip the umount(2) syscall
-f, --force force unmount (in case of an unreachable NFS system)
-i, --internal-only don't call the umount.<type> helpers
-n, --no-mtab don't write to /etc/mtab
-l, --lazy detach the filesystem now, clean up things later
-O, --test-opts <list> limit the set of filesystems (use with -a)
-R, --recursive recursively unmount a target with all its children
-r, --read-only in case unmounting fails, try to remount read-only
-t, --types <list> limit the set of filesystem types
-v, --verbose say what is being done
-h, --help display this help and exit
-V, --version output version information and exit
For more details see umount(8).
root@ubuntu1604:~# umount --help
Usage:
umount [-hV]
umount -a [options]
umount [options] <source> | <directory>
Unmount filesystems.
Options:
-a, --all unmount all filesystems
-A, --all-targets unmount all mountpoints for the given device in the
current namespace
-c, --no-canonicalize don't canonicalize paths
-d, --detach-loop if mounted loop device, also free this loop device
--fake dry run; skip the umount(2) syscall
-f, --force force unmount (in case of an unreachable NFS system)
-i, --internal-only don't call the umount.<type> helpers
-n, --no-mtab don't write to /etc/mtab
-l, --lazy detach the filesystem now, clean up things later
-O, --test-opts <list> limit the set of filesystems (use with -a)
-R, --recursive recursively unmount a target with all its children
-r, --read-only in case unmounting fails, try to remount read-only
-t, --types <list> limit the set of filesystem types
-v, --verbose say what is being done
-h, --help display this help and exit
-V, --version output version information and exit
For more details see umount(8).
[root@centos7 ~]# umount --help
Usage:
umount [-hV]
umount -a [options]
umount [options] <source> | <directory>
Options:
-a, --all unmount all filesystems
-A, --all-targets unmount all mountpoins for the given device
in the current namespace
-c, --no-canonicalize don't canonicalize paths
-d, --detach-loop if mounted loop device, also free this loop device
--fake dry run; skip the umount(2) syscall
-f, --force force unmount (in case of an unreachable NFS system)
-i, --internal-only don't call the umount.<type> helpers
-n, --no-mtab don't write to /etc/mtab
-l, --lazy detach the filesystem now, and cleanup all later
-O, --test-opts <list> limit the set of filesystems (use with -a)
-R, --recursive recursively unmount a target with all its children
-r, --read-only In case unmounting fails, try to remount read-only
-t, --types <list> limit the set of filesystem types
-v, --verbose say what is being done
-h, --help display this help and exit
-V, --version output version information and exit
For more details see umount(8).
SLES12SP1:~ # umount --help
Usage:
umount [-hV]
umount -a [options]
umount [options] <source> | <directory>
Options:
-a, --all unmount all filesystems
-A, --all-targets unmount all mountpoints for the given device in the
current namespace
-c, --no-canonicalize don't canonicalize paths
-d, --detach-loop if mounted loop device, also free this loop device
--fake dry run; skip the umount(2) syscall
-f, --force force unmount (in case of an unreachable NFS system)
-i, --internal-only don't call the umount.<type> helpers
-n, --no-mtab don't write to /etc/mtab
-l, --lazy detach the filesystem now, clean up things later
-O, --test-opts <list> limit the set of filesystems (use with -a)
-R, --recursive recursively unmount a target with all its children
-r, --read-only in case unmounting fails, try to remount read-only
-t, --types <list> limit the set of filesystem types
-v, --verbose say what is being done
-h, --help display this help and exit
-V, --version output version information and exit
For more details see umount(8).
Unix File Systems
Each file system contains the following :
- superblock
- inodes
- data blocks
Superblock
The superblock contains :
- the block size,
- the size of the file system,
- the number of mounts for the file system,
- a pointer to the root of the file system,
- pointers to the free inodes,
- pointers to free data blocks.
Linux maintains multiple redundant copies of the superblock in every file system.
For example, to view the primary and backup superblock locations on ext filesystems, use the following command:
root@debian8:~# mount | grep ext /dev/sda1 on / type ext4 (rw,relatime,errors=remount-ro,data=ordered) root@debian8:~# dumpe2fs /dev/sda1 | grep -i superblock dumpe2fs 1.42.12 (29-Aug-2014) Primary superblock at 0, Group descriptors at 1-1 Backup superblock at 32768, Group descriptors at 32769-32769 Backup superblock at 98304, Group descriptors at 98305-98305 Backup superblock at 163840, Group descriptors at 163841-163841 Backup superblock at 229376, Group descriptors at 229377-229377 Backup superblock at 294912, Group descriptors at 294913-294913 Backup superblock at 819200, Group descriptors at 819201-819201 Backup superblock at 884736, Group descriptors at 884737-884737 Backup superblock at 1605632, Group descriptors at 1605633-1605633
root@ubuntu1604:~# mount | grep ext /dev/sda1 on / type ext4 (rw,relatime,errors=remount-ro,data=ordered) root@ubuntu1604:~# dumpe2fs /dev/sda1 | grep -i superblock dumpe2fs 1.42.13 (17-May-2015) Primary superblock at 0, Group descriptors at 1-1 Backup superblock at 32768, Group descriptors at 32769-32769 Backup superblock at 98304, Group descriptors at 98305-98305 Backup superblock at 163840, Group descriptors at 163841-163841 Backup superblock at 229376, Group descriptors at 229377-229377 Backup superblock at 294912, Group descriptors at 294913-294913 Backup superblock at 819200, Group descriptors at 819201-819201 Backup superblock at 884736, Group descriptors at 884737-884737 Backup superblock at 1605632, Group descriptors at 1605633-1605633
SLES11SP1:~ # mount | grep ext /dev/sda2 on / type ext3 (rw,acl,user_xattr) /dev/sda1 on /boot type ext3 (rw,acl,user_xattr) SLES11SP1:~ # dumpe2fs /dev/sda1 | grep -i superblock dumpe2fs 1.41.9 (22-Aug-2009) Primary superblock at 1, Group descriptors at 2-2 Backup superblock at 8193, Group descriptors at 8194-8194 Backup superblock at 24577, Group descriptors at 24578-24578 Backup superblock at 40961, Group descriptors at 40962-40962 Backup superblock at 57345, Group descriptors at 57346-57346 Backup superblock at 73729, Group descriptors at 73730-73730
To repair an ext file system using a backup superblock use the following command :
# e2fsck -f -b 32768 /dev/sda1 [Enter]
or
# e2fsck -f -b 8193 /dev/sda1 [Enter]
dependant upon which distribution you are using.
Inodes
Each file is represented by an inode. An inode contains the following information:
- the file type : -, d, l, b, c, p, s,
- file permissions, for example : rwx rw- r–,
- the number of hard links,
- the UID of the file creator or the current UID attributed by the chown command,
- the GID of the creating process or the current GID attributed by the chgrp command,
- the file size in bytes,
- the date of the last modification of the file's inode content : ctime,
- the date of the last modification of the file contents : mtime,
- the date of the last access : atime,
- allocation addresses that point to the data blocks used by the file.
For example:
Execute the following command:
root@debian8:~# ls -ld /dev/console /dev/sda1 /etc /etc/passwd crw------- 1 root root 5, 1 Aug 18 11:29 /dev/console brw-rw---- 1 root disk 8, 1 Aug 18 11:29 /dev/sda1 drwxr-xr-x 121 root root 12288 Aug 18 11:29 /etc -rw-r--r-- 1 root root 2094 May 1 20:32 /etc/passwd
root@ubuntu1604:~# ls -ld /dev/console /dev/sda1 /etc /etc/passwd crw------- 1 root root 5, 1 sept. 28 10:31 /dev/console brw-rw---- 1 root disk 8, 1 sept. 28 10:31 /dev/sda1 drwxr-xr-x 129 root root 12288 sept. 28 10:41 /etc -rw-r--r-- 1 root root 2296 mai 3 08:08 /etc/passwd
[root@centos7 ~]# ls -ld /dev/console /dev/sda1 /etc /etc/passwd crw-------. 1 root root 5, 1 Sep 28 10:48 /dev/console brw-rw----. 1 root disk 8, 1 Sep 28 10:48 /dev/sda1 drwxr-xr-x. 136 root root 8192 Sep 28 10:57 /etc -rw-r--r--. 1 root root 2267 Sep 22 14:29 /etc/passwd
SLES12SP1:~ # ls -ld /dev/console /dev/sda1 /etc /etc/passwd crw------- 1 root root 5, 1 Sep 28 10:37 /dev/console brw-rw---- 1 root disk 8, 1 Sep 28 10:37 /dev/sda1 drwxr-xr-x 1 root root 4746 Sep 28 10:38 /etc -rw-r--r-- 1 root root 1335 Sep 20 13:34 /etc/passwd
The first character of each line indicates the file type:
- - - an ordinary file,
- d - a directory,
- l - a symbolic link,
- b - a bloc type peripheral,
- c - a character type peripheral,
- p - a named pipe for communication between processes,
- s - a network socket.
To see the inode numbers, execute the previous command with, in addition, the -i option:
root@debian8:~# ls -ldi /dev/console /dev/sda1 /etc /etc/passwd 5601 crw------- 1 root root 5, 1 Aug 18 11:29 /dev/console 6890 brw-rw---- 1 root disk 8, 1 Aug 18 11:29 /dev/sda1 38995 drwxr-xr-x 121 root root 12288 Aug 18 11:29 /etc 52831 -rw-r--r-- 1 root root 2094 May 1 20:32 /etc/passwd
root@ubuntu1604:~# ls -ldi /dev/console /dev/sda1 /etc /etc/passwd
14 crw------- 1 root root 5, 1 sept. 28 10:31 /dev/console
376 brw-rw---- 1 root disk 8, 1 sept. 28 10:31 /dev/sda1
390913 drwxr-xr-x 129 root root 12288 sept. 28 10:41 /etc
396002 -rw-r--r-- 1 root root 2296 mai 3 08:08 /etc/passwd
[root@centos7 ~]# ls -ldi /dev/console /dev/sda1 /etc /etc/passwd
4683 crw-------. 1 root root 5, 1 Sep 28 10:48 /dev/console
8107 brw-rw----. 1 root disk 8, 1 Sep 28 10:48 /dev/sda1
33595521 drwxr-xr-x. 136 root root 8192 Sep 28 10:57 /etc
35670335 -rw-r--r--. 1 root root 2267 Sep 22 14:29 /etc/passwd
SLES12SP1:~ # ls -ldi /dev/console /dev/sda1 /etc /etc/passwd 4306 crw------- 1 root root 5, 1 Sep 28 10:37 /dev/console 6871 brw-rw---- 1 root disk 8, 1 Sep 28 10:37 /dev/sda1 257 drwxr-xr-x 1 root root 4746 Sep 28 12:02 /etc 58930 -rw-r--r-- 1 root root 1335 Sep 20 13:34 /etc/passwd
Data Blocks
File data is stored in data blocks. In the case of a directory, the data block contains a table referencing the inodes and the names of the contents of the directory.
The name of the file is stored in the parent directory's data block and not in the inode. This means that a file can be referenced by one or more different names. To add a name to a data block, you need to create what is called a hard link.
Hard (Physical) Links
A hard link is created by using the ln command.
Debian
root@debian8:~# cd /tmp; mkdir inode; cd inode; touch file1; ls -ali total 8 140612 drwxr-xr-x 2 root root 4096 Aug 18 13:28 . 130564 drwxrwxrwt 10 root root 4096 Aug 18 13:28 .. 140613 -rw-r--r-- 1 root root 0 Aug 18 13:28 file1
file1 shows an inode number of 140613 and a single name, indicated by the number 1 in the third column:
140613 -rw-r--r-- 1 root root 0 Aug 18 13:28 file1
now create the hard link and check the result:
root@debian8:/tmp/inode# ln file1 file2 root@debian8:/tmp/inode# ls -ali total 8 140612 drwxr-xr-x 2 root root 4096 Aug 18 13:29 . 130564 drwxrwxrwt 10 root root 4096 Aug 18 13:28 .. 140613 -rw-r--r-- 2 root root 0 Aug 18 13:28 file1 140613 -rw-r--r-- 2 root root 0 Aug 18 13:28 file2
Now you can see two lines, one for file1 and a second for file2:
140613 -rw-r--r-- 2 root root 0 Aug 18 13:28 file1 140613 -rw-r--r-- 2 root root 0 Aug 18 13:28 file2
file1 and file2 are referenced by the same inode. As a result the number of names has been increased to two in the thrid column.
Ubuntu
root@ubuntu1604:~# cd /tmp; mkdir inode; cd inode; touch file1; ls -ali total 8 521308 drwxr-xr-x 2 root root 4096 sept. 29 10:26 . 390918 drwxrwxrwt 10 root root 4096 sept. 29 10:26 .. 521340 -rw-r--r-- 1 root root 0 sept. 29 10:26 file1
file1 shows an inode number of 521340 and a single name, indicated by the number 1 in the third column:
521340 -rw-r--r-- 1 root root 0 sept. 29 10:26 file1
now create the hard link and check the result:
root@ubuntu1604:/tmp/inode# ln file1 file2 root@ubuntu1604:/tmp/inode# ls -ali total 8 521308 drwxr-xr-x 2 root root 4096 sept. 29 10:27 . 390918 drwxrwxrwt 10 root root 4096 sept. 29 10:26 .. 521340 -rw-r--r-- 2 root root 0 sept. 29 10:26 file1 521340 -rw-r--r-- 2 root root 0 sept. 29 10:26 file2
Now you can see two lines, one for file1 and a second for file2:
521340 -rw-r--r-- 2 root root 0 sept. 29 10:26 file1 521340 -rw-r--r-- 2 root root 0 sept. 29 10:26 file2
file1 and file2 are referenced by the same inode. As a result the number of names has been increased to two in the thrid column.
RHEL/CentOS
[root@centos7 ~]# cd /tmp; mkdir inode; cd inode; touch file1; ls -ali total 0 287056 drwxr-xr-x. 2 root root 60 Sep 28 12:16 . 11071 drwxrwxrwt. 10 root root 240 Sep 28 12:16 .. 287058 -rw-r--r--. 1 root root 0 Sep 28 12:16 file1
file1 shows an inode number of 287058 and a single name, indicated by the number 1 in the third column:
287058 -rw-r--r--. 1 root root 0 Sep 28 12:16 file1
now create the hard link and check the result:
[root@centos7 inode]# ln file1 file2 [root@centos7 inode]# ls -ali total 0 287056 drwxr-xr-x. 2 root root 80 Sep 28 12:18 . 11071 drwxrwxrwt. 10 root root 240 Sep 28 12:16 .. 287058 -rw-r--r--. 2 root root 0 Sep 28 12:16 file1 287058 -rw-r--r--. 2 root root 0 Sep 28 12:16 file2
Now you can see two lines, one for file1 and a second for file2:
287058 -rw-r--r--. 2 root root 0 Sep 28 12:16 file1 287058 -rw-r--r--. 2 root root 0 Sep 28 12:16 file2
file1 and file2 are referenced by the same inode. As a result the number of names has been increased to two in the thrid column.
SLES
SLES12SP1:~ # cd /tmp; mkdir inode; cd inode; touch file1; ls -ali total 0 442 drwxr-xr-x 1 root root 10 Sep 28 12:23 . 256 drwxrwxrwt 1 root root 112 Sep 28 12:23 .. 443 -rw-r--r-- 1 root root 0 Sep 28 12:23 file1
file1 shows an inode number of 443 and a single name, indicated by the number 1 in the third column:
443 -rw-r--r-- 1 root root 0 Sep 28 12:23 file1
now create the hard link and check the result:
SLES12SP1:/tmp/inode # ln file1 file2 SLES12SP1:/tmp/inode # ls -ali total 0 442 drwxr-xr-x 1 root root 20 Sep 28 12:24 . 256 drwxrwxrwt 1 root root 112 Sep 28 12:23 .. 443 -rw-r--r-- 2 root root 0 Sep 28 12:23 file1 443 -rw-r--r-- 2 root root 0 Sep 28 12:23 file2
Now you can see two lines, one for file1 and a second for file2:
443 -rw-r--r-- 2 root root 0 Sep 28 12:23 file1 443 -rw-r--r-- 2 root root 0 Sep 28 12:23 file2
file1 and file2 are referenced by the same inode. As a result the number of names has been increased to two in the thrid column.
Important - Hard links cannot be created across file system boundaries. A hard link can only be created if the source file exists.
Soft (Symbolic) Links
A soft link is a shortcut to a file or directory. A soft link is created using the same ln command with the -s option.
Debian
root@debian8:/tmp/inode# ln -s file1 file3 root@debian8:/tmp/inode# ls -ali total 8 140612 drwxr-xr-x 2 root root 4096 Aug 18 13:36 . 130564 drwxrwxrwt 10 root root 4096 Aug 18 13:28 .. 140613 -rw-r--r-- 2 root root 0 Aug 18 13:28 file1 140613 -rw-r--r-- 2 root root 0 Aug 18 13:28 file2 140614 lrwxrwxrwx 1 root root 5 Aug 18 13:36 file3 -> file1
Ubuntu
root@ubuntu1604:/tmp/inode# ln -s file1 file3 root@ubuntu1604:/tmp/inode# ls -ali total 8 521308 drwxr-xr-x 2 root root 4096 sept. 29 10:32 . 390918 drwxrwxrwt 10 root root 4096 sept. 29 10:26 .. 521340 -rw-r--r-- 2 root root 0 sept. 29 10:26 file1 521340 -rw-r--r-- 2 root root 0 sept. 29 10:26 file2 521342 lrwxrwxrwx 1 root root 5 sept. 29 10:32 file3 -> file1
RHEL/CentOS
[root@centos7 inode]# ln -s file1 file3 [root@centos7 inode]# ls -ali total 0 287056 drwxr-xr-x. 2 root root 100 Sep 28 12:30 . 11071 drwxrwxrwt. 10 root root 240 Sep 28 12:16 .. 287058 -rw-r--r--. 2 root root 0 Sep 28 12:16 file1 287058 -rw-r--r--. 2 root root 0 Sep 28 12:16 file2 333487 lrwxrwxrwx. 1 root root 5 Sep 28 12:30 file3 -> file1
SLES
SLES12SP1:/tmp/inode # ln -s file1 file3 SLES12SP1:/tmp/inode # ls -ali total 4 442 drwxr-xr-x 1 root root 30 Sep 28 12:26 . 256 drwxrwxrwt 1 root root 112 Sep 28 12:23 .. 443 -rw-r--r-- 2 root root 0 Sep 28 12:23 file1 443 -rw-r--r-- 2 root root 0 Sep 28 12:23 file2 444 lrwxrwxrwx 1 root root 5 Sep 28 12:26 file3 -> file1
Note here that the soft link is referenced by a separate inode.
Important - A soft link can be created across file system boundaries and can be created even when the source file does not exist.
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1)
Not Applicable
