ls

List information about files.

Syntax
      ls [Options]... [File]...

Key
      Sort entries alphabetically if none of -cftuSUX nor --sort.

  -a, --all                  Do not hide entries starting with .

  -A, --almost-all           Do not list implied . and ..

  -b, --escape               Print octal escapes for nongraphic characters

      --block-size=SIZE      Use SIZE-byte blocks

  -B, --ignore-backups       Do not list implied entries ending with ~

  -c                         Sort by change time; with -l: show ctime

  -C                         List entries by columns

      --color[=WHEN]         Control whether color is used to distinguish file
                             types. WHEN may be `never', `always', or `auto'

  -d, --directory            List directory entries instead of contents

  -D, --dired                Generate output designed for Emacs' dired mode

  -f                         Do not sort, enable -aU, disable -lst

  -F, --classify             Append indicator (one of */=@|) to entries

      --format=WORD          Across -x, commas -m, horizontal -x, long -l,
                             single-column -1, verbose -l, vertical -C

      --full-time            List both full date and full time

  -g                         (ignored)

  -G, --no-group             Inhibit display of group information

  -h, --human-readable       Print sizes in human readable format (e.g., 1K 234M 2G)
  -H, --si                   Likewise, but use powers of 1000 not 1024

      --indicator-style=WORD Append indicator with style WORD to entry names:
                             none (default), classify (-F), file-type (-p)

  -i, --inode                Print index number of each file

  -I, --ignore=PATTERN       Do not list implied entries matching shell PATTERN

  -k, --kilobytes            Like --block-size=1024

  -l                         Use a long listing format

  -L, --dereference          List entries pointed to by symbolic links

  -m                         Fill width with a comma separated list of entries

  -n, --numeric-uid-gid      List numeric UIDs and GIDs instead of names

  -N, --literal              Print raw entry names (don't treat e.g. control
                             characters specially)

  -o                         Use long listing format without group info

  -p, --file-type            Append indicator (one of /=@|) to entries

  -q, --hide-control-chars   Print ? instead of non graphic characters

      --show-control-chars   Show non graphic characters as-is (default)

  -Q, --quote-name           Enclose entry names in double quotes
      --quoting-style=WORD   Use quoting style WORD for entry names:
                             literal, shell, shell-always, c, escape

  -r, --reverse              Reverse order while sorting

  -R, --recursive            List subdirectories recursively

  -s, --size                 Print size of each file, in blocks

  -S                         Sort by file size

      --sort=WORD            time -t, version -v, status -c
                             size -S, extension -X, none -U
                             atime -u, access -u, use -u

      --time=WORD            Show time as WORD instead of modification time:
                               atime, access, use, ctime or status;
                               also use this as a sort key if --sort=time

  -t                         sort by modification time

  -T, --tabsize=COLS         assume tab stops at each COLS instead of 8

  -u                         sort by last access time; with -l: show atime

  -U                         do not sort; list entries in directory order

  -v                         sort by version

  -w, --width=COLS           assume screen width instead of current value

  -x                         list entries by lines instead of by columns

  -X                         sort alphabetically by entry extension

  -1                         list one file per line

      --help                 display help and exit

      --version              output version information and exit

The most common options are -a (all files) and -l (long or details)
When output to file the files are listed one per line.

By default, colour is not used to distinguish types of files. That is equivalent to using –color=none.
Using the –color option without the optional WHEN argument is equivalent to using –color=always.
With –color=auto, color codes are output only if standard output is connected to a terminal (tty).

Examples

# List the contents of your home directory
$ ls ~

# list everything in a vertical list:
$ ls -al

total 109
drwxr-xr-x  18 root     root         4096 Jun  9 21:12 ./
drwxr-xr-x  18 root     root         4096 Jun  9 21:12 ../
drwxr-xr-x   2 root     root         4096 Jun  9 21:14 bin/
drwxr-xr-x   3 root     root         1024 Jun  9 20:32 boot/
drwxr-xr-x   6 root     root        36864 Jul 12 10:26 dev/
drwxr-xr-x  34 root     root         4096 Jul 12 10:25 etc/
^
the first column is the file type
d = directory
f = file

# List the directories in the current directory:
$ ls -d */

# list ALL subdirectories
$ ls *

The default behaviour of ls is to only pass color control codes to tty output –color=auto.
To pipe the output to a second command complete with color codes then set –color=always

$ ls -lAXh –color=auto|less -R