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I wanted to know what the unit (bytes, bits, kb) of the output of the ls -l command in Linux is.

Here is an example of what I've got:

-rw-rw-r--    1 guest    guest       39870 Feb 14 19:41 ser_cat
-rw-r--r--    1 guest    guest       19935 Feb 14 19:35 ser_cp
-rw-rw-r--    1 guest    guest       19935 Feb 14 19:29 ser_more

What is the unit of 39870 (the size of ser_cat)?

2 Answers 2

102

That size is in bytes.

You can use ls -lh to print the long listing with human readable file sizes.

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  • 22
    Just a note on the units: ls -h gives 1K (1024 bytes). ls --si gives 1k (1000 bytes). May 29, 2015 at 13:37
  • @ThomasBratt Are you sure? On Debian 10 here, -h seems to give decimal SI units (Gigabytes, Megabytes and Kilobytes). exa shows the same figures/units by default and I get the binary units (Gibibytes, Mebibytes and Kibibytes), resulting in smaller integers, using the -b switch.
    – paradroid
    May 12, 2020 at 13:18
4

We need to add l (long listing option) to show human-readable file sizes (ls -lh). In your case, size of file ser_cat is in 39870 bytes.

-rw-rw-r--    1 guest    guest       39870 Feb 14 19:41 ser_cat
-rw-r--r--    1 guest    guest       19935 Feb 14 19:35 ser_cp
-rw-rw-r--    1 guest    guest       19935 Feb 14 19:29 ser_more

ls -lh command shows all file size information as K for Kibibyte (KiB), M for Mebibyte (MiB) and so on. See this for the difference between kibi and kilo.

Instead of bits they show information in bytes.

ls -lh shows unit (size) information using single character instead of two characters. If no unit information is there, then it means bytes.

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  • 3
    The units for -h are actually Kibibytes and Mebibytes, not Kilobytes and Megabytes. If you want Kilobytes and Megabytes, use --si instead.
    – Ajedi32
    May 16, 2016 at 21:28
  • Updated post to reflect @Ajedi32 point. , Refer [superuser.com/questions/287498/… to understand Differences between KiB and KB
    – Baha
    Oct 4, 2016 at 7:41

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