In the world of Linux | Unix system administration one of our tasks is to perform Linux check disk space. Performing Linux check disk space operation makes us aware about the current utilisation of the mount point within the system.
Here is list of command for Linux check disk space. 
Linux check disk space commands
1. df command.
df is the major native command built inside the linux system used for linux check disk space. df stands for “disk free”. Meaning that, it displays utilization of the mount points in linux. There are various options available for df command. Without any option it displays information like file system , used space , how much space available and also the utilization in terms of percentages as below:
[root@rhel1 ~]# df
Filesystem 1K-blocks Used Available Use% Mounted on
/dev/mapper/vg_rhel1-lv_root
16070076 8763548 6490196 58% /
tmpfs 1960684 36 1960648 1% /dev/shm
/dev/sda1 495844 37181 433063 8% /boot
/dev/mapper/vg_uxtechno-lv_uxtechno
198337 5647 182450 4% /uxtechno
/dev/sde1 1233308 3356 1167304 1% /home
[root@rhel1 ~]#
There are different options within df commands, lets explore one by one.
a. Human readable format
In the sample output without any option displays the utilization in bytes. To make it more informatory use option “-h” along with df command which will display the utilization is Gb. Mb as below:
[root@rhel1 ~]# df -h
Filesystem Size Used Avail Use% Mounted on
/dev/mapper/vg_rhel1-lv_root
16G 8.4G 6.2G 58% /
tmpfs 1.9G 36K 1.9G 1% /dev/shm
/dev/sda1 485M 37M 423M 8% /boot
/dev/mapper/vg_uxtechno-lv_uxtechno
194M 5.6M 179M 4% /uxtechno
/dev/sde1 1.2G 3.3M 1.2G 1% /home
[root@rhel1 ~]#
b. Specific mount-point
In “1a” system displays information related to all the mount points within the system. What if you want information related to any specific mount point. Then you must give the mount point after the df command which will print information related that mount point only. eg. to display information related to /home mount point use below command:
[root@rhel1 ~]# df -h /home Filesystem Size Used Avail Use% Mounted on /dev/sde1 1.2G 3.3M 1.2G 1% /home [root@rhel1 ~]#
c. File system type
Let’s say you also need information related to filesystem type (ext2, ext3 or ext4) in the output. Then use option “-T” along with df command.
[root@rhel1 ~]# df -hT
Filesystem Type Size Used Avail Use% Mounted on
/dev/mapper/vg_rhel1-lv_root
ext4 16G 8.4G 6.2G 58% /
tmpfs tmpfs 1.9G 36K 1.9G 1% /dev/shm
/dev/sda1 ext4 485M 37M 423M 8% /boot
/dev/mapper/vg_uxtechno-lv_uxtechno
ext4 194M 5.6M 179M 4% /uxtechno
/dev/sde1 ext4 1.2G 3.3M 1.2G 1% /home
[root@rhel1 ~]#
d. Limiting the list as per the filesystem type
-
Including certain type of file system type.
In case you only want to (include) display filesystem of the type ext4. Then use “-t” option followed by “Filesystem type” as below:
[root@rhel1 ~]# df -hTt ext4 Filesystem Type Size Used Avail Use% Mounted on /dev/mapper/vg_rhel1-lv_root ext4 16G 8.4G 6.2G 58% / /dev/sda1 ext4 485M 37M 423M 8% /boot /dev/mapper/vg_uxtechno-lv_uxtechno ext4 194M 5.6M 179M 4% /uxtechno /dev/sde1 ext4 1.2G 3.3M 1.2G 1% /home [root@rhel1 ~]#
-
Excluding certain type of filesystem type
Let’s say, you don’t want filesystem type ext4 to be appeared in the output then you must use “-x” followed by type of filesystem.
[root@rhel1 ~]# df -hTx ext4 Filesystem Type Size Used Avail Use% Mounted on tmpfs tmpfs 1.9G 36K 1.9G 1% /dev/shm [root@rhel1 ~]#
The above output excluded all the filesystem with ext4 and only displayed information for the “tmpfs” type of filesystem.
e. inode information.
If you want to print information related to inodes then use option “-i” along with the df command.
[root@rhel1 ~]# df -hi
Filesystem Inodes IUsed IFree IUse% Mounted on
/dev/mapper/vg_rhel1-lv_root
999K 90K 909K 9% /
tmpfs 479K 4 479K 1% /dev/shm
/dev/sda1 126K 39 125K 1% /boot
/dev/mapper/vg_uxtechno-lv_uxtechno
50K 12 50K 1% /uxtechno
/dev/sde1 77K 294 77K 1% /home
[root@rhel1 ~]#
f. All filesystem
In case you want to print information related to all file system which includes dummy filesystem also. Then “-a” option after df command as below:
[root@rhel1 ~]# df -ha
Filesystem Size Used Avail Use% Mounted on
/dev/mapper/vg_rhel1-lv_root
16G 8.4G 6.2G 58% /
proc 0 0 0 - /proc
sysfs 0 0 0 - /sys
devpts 0 0 0 - /dev/pts
tmpfs 1.9G 36K 1.9G 1% /dev/shm
/dev/sda1 485M 37M 423M 8% /boot
none 0 0 0 - /proc/sys/fs/binfmt_misc
sunrpc 0 0 0 - /var/lib/nfs/rpc_pipefs
/dev/mapper/vg_uxtechno-lv_uxtechno
194M 5.6M 179M 4% /uxtechno
/dev/sde1 1.2G 3.3M 1.2G 1% /home
gvfs-fuse-daemon 0 0 0 - /root/.gvfs
[root@rhel1 ~]#
2. du command
“du” command also displays utilization related to file or directory in linux. du stands for “disk usage”.
Basic syntax of du command:
du [options] [<file location> or <dir location>]
a. Human readable
To display output in human readable format ie in terms of Gb or Mb instead of Kb use “-h” option.
[root@rhel1 tmp]# du -h 148K ./orbit-user1 4.0K ./ssh-LFeSg17790 4.0K ./mann 4.0K ./mannu 4.0K ./.esd-0 4.0K ./ssh-PYFhE19514 4.0K ./pulse-BIXXUmlVMfbC 4.0K ./.esd-513 4.0K ./.X11-unix 4.0K ./.ICE-unix 4.0K ./keyring-qO7Ako 4.0K ./pulse-WR3BqwGvaoeJ 84K ./orbit-user2 4.0K ./.esd-514 4.0K ./keyring-N0Gi7c 4.0K ./pulse-0lGpGWbHcush 12K ./orbit-root 492K . [root@rhel1 tmp]#
b. Specific file or directory
To display information specific to any directory or file, use that file or dir followed by du command as below:
E.g. for tmp dir use below command.
[root@rhel1 tmp]# du -h /tmp 148K /tmp/orbit-user1 4.0K /tmp/ssh-LFeSg17790 4.0K /tmp/mann 4.0K /tmp/mannu 4.0K /tmp/.esd-0 4.0K /tmp/ssh-PYFhE19514 4.0K /tmp/pulse-BIXXUmlVMfbC 4.0K /tmp/.esd-513 4.0K /tmp/.X11-unix 4.0K /tmp/.ICE-unix 4.0K /tmp/keyring-qO7Ako 4.0K /tmp/pulse-WR3BqwGvaoeJ 84K /tmp/orbit-user2 4.0K /tmp/.esd-514 4.0K /tmp/keyring-N0Gi7c 4.0K /tmp/pulse-0lGpGWbHcush 12K /tmp/orbit-root 492K /tmp [root@rhel1 tmp]#
c. Summarise output.
In the output 2b you have seen that, all the files or directories utilization have been shown. However, if you don’t want to show this all directories instead you just want information related to that directory only in the output then use “-s” option.
[root@rhel1 ~]# du -sh /tmp 492K /tmp [root@rhel1 ~]#
Please check guide on extending mount point in case your utilization reached threshold.
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