Directory Listings: The ls Command

Basic Usage

  • Displays directory content

  • Without any options ⟶ names only

  • No metadata, no nothing

    • When terminal supports color output, different file types are colored differently ⟶ minimal file type hintingx

  • No further arguments ⟶ current working directory (CWD)

    $ pwd
/home/jfasch
$ ls
Documents  Downloads  Homebrain  Pictures  tmp  venv  work

  • Displaying non CWD directory:

    $ ls Documents/
Buchhaltung.csv  python-3.10.0-docs-html  python-doc.zip  Umsatzsteuerbescheid1.pdf

Many Options

Option

Description

-l

Long listing ⟶ show metadata

-a

Show hidden files

-d

Show directory, not its content (ls /etc would show /etc’s content)

-h

File sizes (and possibly others) in human readable form (e.g., 1.0M instead of 1048576)

-t

Sort by timestamp

-R

Recurse into directories

…

man -s 1 ls

Metadata

  • Showing names only is rarely sufficient

  • ⟶ file type, timestamp, owner, group owner, permissions, …

$ ls -l /etc/passwd
-rw-r--r-- 1 root root 2746 Mar  3 14:12 /etc/passwd

-

File type (-: regular file)

rw-r--r--

Permissions

1

Reference count (⟶ Symbolic Links, Hard Links)

root

Owner

root

Group owner

2746

File size

Mar 3 14:12

Last modification timestamp

/etc/passwd

Entry name

Hidden Files

  • Per convention: all names starting with a dot (“.”) are not shown

  • ⟶ “hidden” files

  • … unless -a is given

$ ls -a
.   .bash_history  .bash_profile  .bashrc~  .config  .dia       Downloads  .emacs.d    .gnupg     .ipython  .lesshst  .mozilla  .pki             .ssh         .thunderbird  .var  .vscode  .zoom
..  .bash_logout   .bashrc        .cache    Desktop  Documents  .emacs     .gitconfig  Homebrain  .jupyter  .local    Pictures  .python_history  .subversion  tmp           venv  work

  • Best combined with -al

$ ls -al
total 68
drwx------. 1 jfasch jfasch   490 Mar  9 17:51 .
drwxr-xr-x. 1 root   root      36 Mar  3 14:12 ..
-rw-------. 1 jfasch jfasch 36817 Mar  9 17:31 .bash_history
-rw-r--r--. 1 jfasch jfasch    18 Jan 26  2021 .bash_logout
-rw-r--r--. 1 jfasch jfasch   141 Jan 26  2021 .bash_profile
-rw-r--r--. 1 jfasch jfasch   610 Oct 28 12:43 .bashrc
drwx------. 1 jfasch jfasch   910 Mar  7 16:20 .cache
drwxr-xr-x. 1 jfasch jfasch   682 Mar  3 16:21 .config
drwxr-xr-x. 1 jfasch jfasch     0 Mar  9 16:11 Desktop
drwxr-xr-x. 1 jfasch jfasch   112 Feb 12 16:26 .dia
drwxr-xr-x. 1 jfasch jfasch   154 Mar  9 17:22 Documents
drwxr-xr-x. 1 jfasch jfasch  2332 Mar  9 12:31 Downloads
lrwxrwxrwx. 1 jfasch jfasch    42 Sep 27 12:16 .emacs -> /home/jfasch/Homebrain/local-config/.emacs
drwx------. 1 jfasch jfasch  5080 Mar  7 12:09 .emacs.d
lrwxrwxrwx. 1 jfasch jfasch    46 Sep 27 19:21 .gitconfig -> /home/jfasch/Homebrain/local-config/.gitconfig
lrwxrwxrwx. 1 jfasch jfasch    43 Sep 27 18:41 .gnupg -> /home/jfasch/Homebrain/local-config/.gnupg/
drwxrwxr-x. 1 jfasch jfasch   536 Feb 25 18:32 Homebrain
drwxr-xr-x. 1 jfasch jfasch    74 Nov 16 21:53 .ipython
drwxrwxr-x. 1 jfasch jfasch    16 Nov 16 21:54 .jupyter
-rw-------. 1 jfasch jfasch    20 Mar  8 14:00 .lesshst
drwx------. 1 jfasch jfasch    32 Oct 18 13:10 .local
drwx------. 1 jfasch jfasch   100 Mar 23  2019 .mozilla
drwxr-xr-x. 1 jfasch jfasch    34 Mar  9 13:57 Pictures
drwx------. 1 jfasch jfasch    10 Oct  8 09:31 .pki
-rw-------. 1 jfasch jfasch     0 Mar  9 17:30 .python_history
drwx------. 1 jfasch jfasch   174 Feb 18 13:09 .ssh
drwxrwxr-x. 1 jfasch jfasch    54 Nov  5 10:50 .subversion
drwx------. 1 jfasch jfasch   118 Sep 23  2019 .thunderbird
drwxrwxr-x. 1 jfasch jfasch   698 Mar  9 17:31 tmp
drwxr-xr-x. 1 jfasch jfasch     6 Sep 27 12:40 .var
drwxrwxr-x. 1 jfasch jfasch   106 Feb 24 20:19 venv
drwxr-xr-x. 1 jfasch jfasch    38 Oct  8 09:31 .vscode
drwxr-xr-x. 1 jfasch jfasch   902 Feb 16 11:12 work
drwx------. 1 jfasch jfasch    80 Mar  2 17:23 .zoom

File Types

  • Everything is a file 😎

  • But there are different types of files 🙄

    ls -l, first character

    Type

    -

    Regular file

    d

    Directory

    c

    Character device

    b

    Block device

    l

    Symbolic link

    p

    Named pipe

  • Examples …

    $ ls -l /etc/passwd
-rw-r--r--. 1 root root 2746 Mar  3 14:12 /etc/passwd

    $ ls -ld Documents
drwxr-xr-x. 1 jfasch jfasch 154 Mar  9 17:22 Documents

    $ ls -l /dev/{zero,null}
crw-rw-rw-. 1 root root 1, 3 Mar  7 12:10 /dev/null
crw-rw-rw-. 1 root root 1, 5 Mar  7 12:10 /dev/zero

    $ ls -al .emacs
lrwxrwxrwx. 1 jfasch jfasch 42 Sep 27 12:16 .emacs -> /home/jfasch/Homebrain/local-config/.emacs