Directory Listings: The ls Command

Documentation

• man -s 1 ls

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