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df command

df - report file system disk space usage​

The df command in Linux is a utility used to display disk space usage for mounted filesystems. It’s essential for checking how much space is available, used, or free on your drives.

Usage: df [OPTION]... [FILE]...

  • FILE: Optional path to a file or directory to report its filesystem (if omitted, shows all mounted filesystems).
  • OPTION: Flags to modify output format or content.

Common Options

OptionDescription
-hHuman-readable sizes (e.g., GB, MB)
-TShow filesystem type
--totalAdd a total summary row
-tInclude only specific types
-xExclude specific types
-iShow inode usage instead of blocks

Examples​

  • Basic Usage

    Run df without options to see disk usage for all mounted filesystems in 512-byte blocks.

    df
    • Output (example): 
      Filesystem     1K-blocks    Used Available Use% Mounted on
      /dev/sda1      104857600 52428800 52428800  50% /
      /dev/sdb1       20971520  1048576 19922944   5% /mnt/data
    • Explanation:
      • Filesystem: Device or mount point.
      • 1K-blocks: Total size in kilobytes.
      • Used: Space used.
      • Available: Space free.
      • Use%: Percentage used.
      • Mounted on: Mount point.

  • Human-Readable Output

    Use -h to display sizes in a more readable format (e.g., GB, MB).

    df -h
    • Output: 
      Filesystem      Size  Used Avail Use% Mounted on
      /dev/sda1      100G   50G   50G  50% /
      /dev/sdb1       20G  1.0G   19G   5% /mnt/data
    • Sizes are shown as G (gigabytes), M (megabytes), etc.

  • Specific Filesystem

    Pass a file or directory to see only its filesystem.

    df -h /mnt/data
    • Output: 
      Filesystem      Size  Used Avail Use% Mounted on
      /dev/sdb1       20G  1.0G   19G   5% /mnt/data

  • Show Filesystem Type

    Use -T to include the filesystem type (e.g., ext4, ntfs).

    df -hT
    • Output: 
      Filesystem     Type      Size  Used Avail Use% Mounted on
      /dev/sda1      ext4      100G   50G   50G  50% /
      /dev/sdb1      ntfs       20G  1.0G   19G   5% /mnt/data

  • Total Summary

    Use --total to add a summary row with totals.

    df -h --total
    • Output: 
      Filesystem      Size  Used Avail Use% Mounted on
      /dev/sda1      100G   50G   50G  50% /
      /dev/sdb1       20G  1.0G   19G   5% /mnt/data
      total          120G   51G   69G  43% -

  • Filtering by Type

    Use -t to show only specific filesystem types.

    df -h -t ext4
    • Output: 
      Filesystem      Size  Used Avail Use% Mounted on
      /dev/sda1      100G   50G   50G  50% /

  • Excluding Types

    Use -x to exclude specific filesystem types (e.g., temporary filesystems like tmpfs).

    df -h -x tmpfs
    • Omits tmpfs entries often used for memory-based mounts.

To get help related to the df command use --help option​

$ df --help
Usage: df [OPTION]... [FILE]...
Show information about the file system on which each FILE resides,
or all file systems by default.

Mandatory arguments to long options are mandatory for short options too.
  -a, --all             include pseudo, duplicate, inaccessible file systems
  -B, --block-size=SIZE  scale sizes by SIZE before printing them; e.g.,
                           '-BM' prints sizes in units of 1,048,576 bytes;
                           see SIZE format below
  -h, --human-readable  print sizes in powers of 1024 (e.g., 1023M)
  -H, --si              print sizes in powers of 1000 (e.g., 1.1G)
  -i, --inodes          list inode information instead of block usage
  -k                    like --block-size=1K
  -l, --local           limit listing to local file systems
      --no-sync         do not invoke sync before getting usage info (default)
      --output[=FIELD_LIST]  use the output format defined by FIELD_LIST,
                               or print all fields if FIELD_LIST is omitted.
  -P, --portability     use the POSIX output format
      --sync            invoke sync before getting usage info
      --total           elide all entries insignificant to available space,
                          and produce a grand total
  -t, --type=TYPE       limit listing to file systems of type TYPE
  -T, --print-type      print file system type
  -x, --exclude-type=TYPE   limit listing to file systems not of type TYPE
  -v                    (ignored)
      --help     display this help and exit
      --version  output version information and exit

Display values are in units of the first available SIZE from --block-size,
and the DF_BLOCK_SIZE, BLOCK_SIZE and BLOCKSIZE environment variables.
Otherwise, units default to 1024 bytes (or 512 if POSIXLY_CORRECT is set).

The SIZE argument is an integer and optional unit (example: 10K is 10*1024).
Units are K,M,G,T,P,E,Z,Y (powers of 1024) or KB,MB,... (powers of 1000).
Binary prefixes can be used, too: KiB=K, MiB=M, and so on.

FIELD_LIST is a comma-separated list of columns to be included.  Valid
field names are: 'source', 'fstype', 'itotal', 'iused', 'iavail', 'ipcent',
'size', 'used', 'avail', 'pcent', 'file' and 'target' (see info page).

For more details, check the manual with man df

Last updated on by AB