Ls
ls (abbreviated from "List") is a command in Unix-like operating systems. It is similar to "dir" in DOS.When executed, the ls command lists the contents of the current directory (or the given arguments) in the Unix-like command line interface (CLI). Seeming like one of the most used Unix commands, it's appropriately loaded with available options.
| Table of contents |
|
2 Sample ls Search 3 Some ls command line options 4 Breakdown of output 5 Type column description 6 Permissions description |
An ls utility first appeared in Version 5 AT&T UNIX. Today, two popular versions of ls include the Free Software Foundation's (part of the GNU coreutils package) and the one released by various BSD distributions, such as FreeBSD, OpenBSD, NetBSD, and Apple Computer's Darwin. Both are free software and open source.
The output given by ls in long listing form is broken into columns, as can be seen above. These columns can then be broken down to acquire information about listed files, directories and devices.
This is the tabular form of the first two listed items from the sample above with headings to explain each column:
History
Sample ls Search
Here is a sample display of its usage:
$ ls -laF
total 4
drwxr-xr-x 10 Brandon None 0 Sep 30 16:48 ./
drwxr-xr-x 10 Brandon None 0 Sep 30 16:48 ../
drwxr-xr-x 3 Brandon None 0 Sep 30 19:02 bin/
-rw-r--r-- 1 root None 89 Dec 16 12:24 test
-rwxr-xr-x 1 Brandon None 57 Sep 30 19:22 cygwin.bat*
-rw-r--r-- 1 Brandon None 766 Sep 30 19:22 cygwin.ico
drwxr-xr-x 15 Brandon None 0 Sep 30 16:48 etc/
drwxr-xr-x 3 Brandon None 0 Sep 30 19:27 home/
drwxr-xr-x 21 Brandon None 0 Sep 30 19:02 lib/
drwxr-xr-x 2 Brandon None 0 Sep 30 19:14 sbin/
-rw-r--r-- 1 Brandon None 22 Dec 16 12:24 testb3
drwxr-xr-x 3 Brandon None 0 Sep 30 19:02 tmp/
drwxr-xr-x 20 Brandon None 0 Sep 30 19:02 usr/
drwxr-xr-x 6 Brandon None 0 Sep 30 19:02 var/
Some ls command line options
ls has a number of command line options, or "switches", that can modify the output. Some of these options are
-F: adds a character that denotes the file's type, (/ for directories, * for executables, @ for links)
-R: recursively lists contents in all subdirectories
-l: long file format, including time, date, permissions and so on.
-a: include dot and hidden files
-f: unsorted outputBreakdown of output
| Type | Permissions | Number of hard links | Owner | Group | Size | Date modified | Listing name |
|---|---|---|---|---|---|---|---|
| d | rwxr-xr-x | 3 | Brandon | None | 0 | Sep 30 19:02 | bin/ |
| - | rw-r--r-- | 1 | root | None | 89 | Dec 16 12:24 | test |
The very first character in a long listing gives the type of file.
Type column description
| Character | Type |
|---|---|
| - | Normal file |
| b | Block device |
| c | Character device |
| d | Directory |
| l | Symbolic link |
| p | Named pipe (FIFO) |
| s | Domain socket |
example:
As for the individual character meanings, the following is meant to explain that:
r - read permission;Permissions description
rwxr-xr--
The first three characters represent the owner's permissions on the item, the next three the group's permissions, the last, everyone else.
Meaning of Characters by Character
w - write permission;
x - execute permission;
- - no permission;
