Linux / Unix: Checking Free Disk Space

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How do I check free disk space in Linux or UNIX operating system? I’ve migrated from Windows NT to Linux and looking forward to get more information about free disk space on a Unix-like systems using command line.

Both Linux and UNIX-like systems offers two commands for checking out free disk space:

(a) df command : Report file system disk space usage.

(b) du command : Estimate file space usage.

df command examples – to check free disk space

Type df -h or df -k to list free disk space:
$ df -h
OR
$ df -k
Outputs:

Filesystem             Size   Used  Avail Use% Mounted on
/dev/sdb1               20G   9.2G   9.6G  49% /
varrun                 393M   144k   393M   1% /var/run
varlock                393M      0   393M   0% /var/lock
procbususb             393M   123k   393M   1% /proc/bus/usb
udev                   393M   123k   393M   1% /dev
devshm                 393M      0   393M   0% /dev/shm
lrm                    393M    35M   359M   9% /lib/modules/2.6.20-15-generic/volatile
/dev/sdb5               29G   5.4G    22G  20% /media/docs
/dev/sdb3               30G   5.9G    23G  21% /media/isomp3s
/dev/sda1              8.5G   4.3G   4.3G  51% /media/xp1
/dev/sda2               12G   6.5G   5.2G  56% /media/xp2
/dev/sdc1               40G   3.1G    35G   9% /media/backup

The df utility displays statistics about the amount of free disk space on the specified file system or on the file system of which file is a part. Values are displayed in 512-byte per block counts. -H option is called as “Human-readable” output. It use unit suffixes: Byte, Kilobyte, Megabyte, Gigabyte, Terabyte and Petabyte in order to reduce the number of digits to four or fewer using base 10 for sizes i.e. you see 30G (30 Gigabyte).

du command examples

du shows how much space one ore more files or directories is using, enter:
$ du -sh
Sample outputs:

Fig.01: Unix df and du command outputs from my FreeBSD server
Fig.01: Unix df and du command outputs from my FreeBSD server

The -s option summarize the space a directory is using and -h option provides “Human-readable” output.

GUI program

Above programs are good if GUI is not installed or you are working with remote system over the ssh based session. Linux and UNIX-like oses comes with KDE and Gnome desktop system. You will find Free Disk Space Applet located under GUI menus. Here is a sample from Fedora Linux version 22 system:


(click to enlarge)

See also

  1. Shell script to watch the disk space
  2. Why command df and du reports different output?

Posted by: Vivek Gite

The author is the creator of nixCraft and a seasoned sysadmin and a trainer for the Linux operating system/Unix shell scripting. He has worked with global clients and in various industries, including IT, education, defense and space research, and the nonprofit sector. Follow him on Twitter, Facebook, Google+.

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