Lesson 3: Listing directories¶
To list the contents of a directory, we need to use the
ls command. Below is a sample output
when running ls:
[learner ~]$ ls
directory1 directory2 file1
[learner ~]$
If there are no files or directories, we can expect to see no output. The default sorting order is alphabetical then numerical if the directory is not empty.
Directory shortcuts¶
For reference, the below shortcuts can be used by ls and other
commands to reference directories without using the whole (absolute)
path:
Shortcut Literal Interpretation
------------------ ------------------------------------------------------------------------------
`.` The current directory
`..` The parent directory - may be chained to navigate up the directory hierarchy
`~` The current user's home directory
The ls command can be used to list the contents of any directory,
not necessarily the one that you are currently in. Try the following:
[learner ~]$ ls /
bin dev etc lib lost+found mnt proc run srv tmp var
boot environment home lib64 media opt root sbin sys usr
[learner ~]$ ls /etc/bashrc
/etc/bashrc
[learner ~]$ ls ..
learner
[learner ~]$ ls ../..
bin dev etc lib lost+found mnt proc run srv tmp var
boot environment home lib64 media opt root sbin sys usr
Notice how the output of ls / and ls ../.. are identical? That is
because the ls ../.. command used a relative path to reference two
directories up from your home directory (the root directory).
Hidden Files and Directories¶
Like other operating systems, Linux also uses hidden files (beginning
with a dot), which are not displayed in the output of ls by default.
To also list hidden entries, add the -a flag to ls, for example:
[learner learning_linux]$ ls -a ~
. .. .bashrc .hiddenfile directory1 directory2 file1
You can see that '.bashrc' and '.hiddenfile' are hidden files.
Many applications use configuration files allowing the user to customise how the application works; Configuration files are often stored as a hidden file in the user's home directory