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 getting more information about free disk space on Unix-like systems using the command line. Can you tell me the Linux command to check the free disk space?

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
Sample outputs that show disk space utilization:

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. The -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).

How to check free disk space in Linux

To see the file system’s complete disk usage pass the -a option:
df -a
Find out disk usage and filesystem type by passing the -T option:
df -T
Want to get used and free inodes information on Linux? Try:
df -i
Linux Checking Free Disk Space Command

du command examples for checking free and used disk space

The du command 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.

Say hello to ncdu command

ncdu (NCurses Disk Usage) is a curses-based version of the well-known ‘du’, and provides a fast way to see what directories are using your disk space. One can install with the following apt command/apt-get command:
sudo apt install ncdu
For RHEL/CentOS, first enable EPEL repo (see CentOS 8 turn on EPEL repo and RHEL 8 enable epel repo) and type the following yum command:
sudo yum install ncdu
Now just type:
ncdu
ncdu [dir]
ncdu /etc/
Linux command to check disk space

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)

Conclusion

You learned how to keep track of disk utilization, and disk space with various Linux and Unix commands.

Posted by: Vivek Gite

The author is the creator of nixCraft and a seasoned sysadmin, DevOps engineer, and a trainer for the Linux operating system/Unix shell scripting. Get the latest tutorials on SysAdmin, Linux/Unix and open source topics via RSS/XML feed or weekly email newsletter.

Join the discussion at www.nixcraft.com

Historical Comment Archive

59 comment

  17. How do i check the total size of the disk on HP ES45 server, not free space, what i mean is the total size of the disk on the said server.

  18. yes, Its helpful, but I have a directory called /dev/sda5

    and its using 40% space, and I can’t identify, what is there in it, can you tell me how to look into it.

  38. Hi when I give command df -h output shows tmpfs contains 4 gigs space. Is it possible and harmless to free-up this space?

  44. Thank You. Just needed info for every one to simply find what they usual need in unix

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