The "ls" Utility (And Hidden Files)
July 19, 1998
Wow, so now you are zipping all about the
file system. However, you still can't do much in any of the
directories you move to until you have some means of reading the
contents of the directories you have moved to.
To get a directory listing, you will use
the "ls" utility which follows the rules described in the table
below:
| Syntax |
Example |
Description |
| ls options filelist. |
ls -l /home/selena/public_html/*.html |
Lists the specified contents of the specified
directory according to the options setting. |
The options for the "ls" command are described in
the table below:
| Option |
Description |
| -A |
Lists "ALL" files (including hidden ones) but not the
current or parent directories ("." or ".."). |
| -a |
Lists "ALL" files including hidden ones and both
current and parent directories ("." and ".."). |
| -C |
Lists files in columns sorted from top to bottom, left
to right. |
| -d |
lists directory names only.
This is very useful since "ls directory_name" will give you the
listing of that directory rather than showing you if the named
directory is actually in the current. |
| -F |
Adds a "/" for directories and a "*" for executables. |
| -i |
Lists the inode number. |
| -l |
Provides a "long" listing with details about
such things as file permission, age, date created,
date of last modification, etc. |
| -r |
Reverses the sort order. |
| -R |
Lists sub-directories recursively. |
| -x |
Lists files in columns sorted from left
to right then top to bottom. |
Here are some examples of using the
"ls" command. Note that you can use multiple options at
one time by simply adding them to the option list.
![[LS Command Example]](Images/ls_options.gif)
Hidden Files
Notice in the example above, the ls command
turned up quite a different file list than the ls -a even though
they were listing the same directory. This is because the ls -a
command lists hidden files as well as normal files.
A Hidden File is a file whose name begins with
a period. These files are usually administrative files and
are often distracting when you are doing your daily work. Thus
UNIX hides them unless you specifically ask to see them with the
-a option
Okay, here are some more examples of the ls
utility
![[LS Command Example 2]](Images/ls_options1.gif)
Now you practice using the "ls"
utility in some of the directories you moved to in the last
section.
Focus on the "-l" Option
Before moving on, we should say a little bit more
about the "-l" option because you will find yourself using this
one quite a bit when you want to know more information about the
files and directories in a listing.
The image below shows a typical "-l"
listing. In the image you will see that there are several fields
listed for each file.
![[LS -l Command Example]](Images/ls-l_options.gif)
The following table overviews the information
provided by the -l option...
| Column |
Description |
| File Type |
Is this a regular file or a directory. "-" denotes
a regular file, "d" denotes a directory, "c" denotes a
character special file, a "b" specifies a block special file,
a "l" represents a symbolic link, and a "p" specified a named
pipe. |
| Permissions |
User, Group and World privileges. We will discuss this
in much greater detail in just a moment |
| Link Count |
The number of names for this file or directory |
| Owner |
We will discuss this later |
| Group |
We will discuss this later |
| Size |
The size of the file in bytes |
| Modification Date |
The last time the file was modified |
| File name |
The name of the UNIX Version. No just kidding. The
file's name |
The ls -l option also includes several options
that affect the listing. These options are shown below:
| Option |
Description |
| -c |
Sorts by the last time the inode was changed
with the -t option |
| -t |
Sorts listing by modification time. |
| -u |
Sorts by the last time accessed. |
Additional Resources:
The "cd" Command
Introduction to UNIX for Web Developers | Table of Contents
Permissions
|
