How to use df command to check disk space in Linux? (code example)

On Linux based systems, we can use the df command to get detailed information about the system disk space usage. So how to use the df command? The following article will show you how to use the df command to check disk space in Linux. I hope it will be helpful to you.

Linux df command

The df command can be used to check the disk space usage in the Linux file system , that is, disk usage. [Video tutorial recommendation: Linux tutorial]

If used without any parameters, the df command will display information about all mounted file systems:

# df

Output:

Filesystem     1K-blocks      Used Available Use% Mounted on
dev              8172848         0   8172848   0% /dev
run              8218640      1696   8216944   1% /run
/dev/nvme0n1p3 222284728 183057872  27865672  87% /
tmpfs            8218640    150256   8068384   2% /dev/shm
/dev/nvme0n1p1    523248    107912    415336  21% /boot
/dev/sda1      480588496 172832632 283320260  38% /data

Each line includes information about the file system name (Filesystem), size (1K-blocks), used space (Used), available space (Available), used space percentage (Use%) and The information file system of the directory is mounted (Mounted on).

How to display disk space usage in human readable format?

By default, the df command displays disk space in units of 1 KB and displays the size of used disk space and available disk space in kilobytes.

This is very inconvenient, how can I display disk space usage in human readable format (megabytes and gigabytes)?

To view the information in human-readable format (megabytes and gigabytes), pass the following -h option:

# df -h

Output:

Filesystem     1K-blocks      Used Available Use% Mounted on
Filesystem      Size  Used Avail Use% Mounted on
dev             7.8G     0  7.8G   0% /dev
run             7.9G  1.8M  7.9G   1% /run
/dev/nvme0n1p3  212G  176G   27G  88% /
tmpfs           7.9G  145M  7.7G   2% /dev/shm
/dev/nvme0n1p1  511M  106M  406M  21% /boot
/dev/sda1       459G  165G  271G  38% /data

How to display the file system type?

To display the file system type, you need to use the command after the df following -T option:

# df -t

Output:

Filesystem     Type     1K-blocks      Used Available Use% Mounted on
dev            devtmpfs   8172848         0   8172848   0% /dev
run            tmpfs      8218640      1744   8216896   1% /run
/dev/nvme0n1p3 ext4     222284728 183666100  27257444  88% /
tmpfs          tmpfs      8218640    383076   7835564   5% /dev/shm
/dev/nvme0n1p1 vfat        523248    107912    415336  21% /boot
/dev/sda1      ext4     480588496 172832632 283320260  38% /data

If you want To limit the list to a specific type of file system, use the -t option followed by the type. For example, to list all ext4 partitions to run:

# df -t vfat

Output:

Filesystem     1K-blocks      Used Available Use% Mounted on
/dev/nvme0n1p1    523248    107912    415336  21% /boot

Similar to above, use the -x option to limit the output to non-specific types of file systems.

How to display Inode usage?

When used with the -i option, the df command displays information about file system inode usage. For example, to display information about an inode on a file system mounted to the system root / in a human-readable format, one would use:

# df -ih /

Output:

Filesystem     Inodes IUsed IFree IUse% Mounted on
/dev/nvme0n1p3    14M  1.9M   12M   14% /

Explanation: The inode is Unix /A data structure in a Linux file system that contains information about a file or directory, such as its size, the owner's User ID, the file's read, write, and execute permissions, etc.

How to specify the output format?

The df command can specify the output format. If you want to limit the information fields displayed in the df output, you need to use the "--output[=FIELD_LIST]" option. where "FIELD_LIST" is a comma-separated list of columns to include in the output; each field may be used only once.

Valid field names are:

● source - file system source.

● fstype - file system type.

● ital - total number of inodes.

● iused - the number of inodes used.

● iavail - the number of available inodes.

● ipcent - the percentage of inodes used.

● size - total disk space.

● used - used disk space.

● available - Available disk space.

● pcent - The percentage of used space.

● file - if a filename is specified on the command line.

● target - the installation point.

For example, output showing all ext4 partitions in human-readable format, showing only the file system name and size and the percentage of used space that will be used:

# df -h -t ext4 --output=source,size,pcent

Output:

Filesystem      Size Use%
/dev/nvme0n1p3  212G  88%
/dev/sda1       459G  38%

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