Ls

In computing, codice_1 is a command to "list" computer files in Unix and Unix-like operating systems. codice_1 is specified by POSIX and the Single UNIX Specification. When invoked without any arguments, ls lists the files in the current working directory. The command is also available in the EFI shell. In other environments, such as DOS, OS/2, and Microsoft Windows, similar functionality is provided by the codice_3 command. The numerical computing environments MATLAB and GNU Octave include an codice_1 
function with similar functionality.
History.
An codice_1 utility appeared in the first version of AT&T UNIX, the name inherited from a similar command in Multics also named 'ls', short for the word "list". is part of the X/Open Portability Guide since issue 2 of 1987. It was inherited into the first version of POSIX.1 and the Single Unix Specification.
An codice_1 command is also part of ASCII's "MSX-DOS2 Tools" for MSX-DOS version 2.
Today, the two popular versions of codice_1 are the one provided with the GNU coreutils package, and that released by various BSD variants. Both are free software and open source, and have only minor syntax differences. The version of codice_1 bundled in GNU coreutils was written by Richard Stallman and David MacKenzie.
Behavior.
Unix and Unix-like operating systems maintain the idea of a "current working directory", that is, where one is currently positioned in the hierarchy of directories. When invoked without any arguments, codice_1 lists the files in the current working directory. If another directory is specified, then codice_1 will list the files there, and in fact the user may specify any list of files and directories to be listed.
Files names starting with "." are not listed unless codice_11 (show all) is specified, codice_12 (show all except "." and "..") is specified, or the files are specified explicitly.
Without options, codice_1 displays files names only. The most common options to display additional information are:
Additional options controlling how files are displayed include:
It is frequently possible to highlight different types of files with different colors, instead of with characters as codice_15 would. This is an area where the two main codice_1 versions differ:
When the option to use color to indicate file types is selected, the output might look like:
 -rw-r--r-- 1 tsmitt nregion 26650 Dec 20 11:16 audio.ogg 
 brw-r--r-- 1 tsmitt nregion 64, 64 Jan 27 05:52 bd-block-device 
 crw-r--r-- 1 tsmitt nregion 64, 255 Jan 26 13:57 cd-character-device 
 -rw-r--r-- 1 tsmitt nregion 290 Jan 26 14:08 image.png 
 drwxrwxr-x 2 tsmitt nregion 48 Jan 26 11:28 di-directory 
 -rwxrwxr-x 1 tsmitt nregion 29 Jan 26 14:03 ex-executable 
 -rw-r--r-- 1 tsmitt nregion 0 Dec 20 09:39 fi-regular-file 
 lrwxrwxrwx 1 tsmitt nregion 3 Jan 26 11:44 ln-soft-link -> dir 
 lrwxrwxrwx 1 tsmitt nregion 15 Dec 20 10:57 or-orphan-link -> mi-missing-link 
 drwxr-xrwx 2 tsmitt nregion 4096 Dec 20 10:58 ow-other-writeable-dir 
 prw-r--r-- 1 tsmitt nregion 0 Jan 26 11:50 pi-pipe 
 -rwxr-sr-x 1 tsmitt nregion 0 Dec 20 11:05 sg-setgid 
 srw-rw-rw- 1 tsmitt nregion 0 Jan 26 12:00 so-socket 
 drwxr-xr-t 2 tsmitt nregion 4096 Dec 20 10:58 st-sticky-dir 
 -rwsr-xr-x 1 tsmitt nregion 0 Dec 20 11:09 su-setuid 
 -rw-r--r-- 1 tsmitt nregion 10240 Dec 20 11:12 compressed.gz 
 drwxrwxrwt 2 tsmitt nregion 4096 Dec 20 11:10 tw-sticky-other-writeable-dir 
Sample usage.
The following example demonstrates the output of the codice_1 command given two different arguments:
$ ls -l
drwxr--r-- 1 fjones editors 4096 drafts
-rw-r--r-- 1 fjones editors 30405 edition-32
-r-xr-xr-x 1 fjones bookeepers 8460 edit.sh
$ ls -F
drafts/
edition-32
edit.sh*
In the above example, the user codice_32 has a directory named codice_33, a regular file named codice_34, and an executable named codice_35 in his home directory. codice_1 uses Unix file permission notation to define the access for the user(i.e. himself), group members for various groups and other users. 
drwxr--r-- 1 fred editors 4096 Mar 1 2007 drafts
In this example, <samp>drafts</samp> is a directory (denoted by the file descriptor <samp>d</samp>), and the characters after this indicate the permissions: