When you first login, your current working directory is your home directory. Your home directory has the same name as your user-name, for example, compsci-user, and it is where your personal files and subdirectories are saved.
To find out what is in your home directory, type
The ls command ( lowercase L and lowercase S ) lists the contents of your current working directory.
There may be no files visible in your home directory, in which case, the UNIX prompt will be returned. Alternatively, there may already be some files inserted by the System Administrator when your account was created.
ls does not, in fact, cause all the files in your home directory to be listed, but only those ones whose name does not begin with a dot (.) Files beginning with a dot (.) are known as hidden files and usually contain important program configuration information. They are hidden because you should not change them unless you are very familiar with Linux!
To list all files in your home directory including those whose names begin with a dot, type
compsci-user@tim:~$ ls -a
ls is an example of a command which can take options: -a is an example of an option. The options change the behaviour of the command. There are online manual pages that tell you which options a particular command can take, and how each option modifies the behaviour of the command. (See later in this tutorial)
mkdir (make directory)
We will now make a subdirectory in your home directory to hold the files you will be creating and using in the course of this tutorial. To make a subdirectory called unixstuff in your current working directory type
compsci-user@tim:~$ mkdir testdir
To see the directory you have just created, type
cd (change directory) The command cd directory means change the current working directory to 'directory'. The current working directory may be thought of as the directory you are in, i.e. your current position in the file-system tree.
To change to the directory you have just made, type
compsci-user@tim:~$ cd testdir
Type ls to see the contents (which should be empty)
Make another directory inside the testdir directory called backups
Still in the testdir directory, type
compsci-user@tim:~$ ls -a
As you can see, in the testdir directory (and in all other directories), there are two special directories called (.) and (..)
In Linux, (.) means the current directory, so typing
compsci-user@tim:~$ cd .
means stay where you are (the testdir directory).
This may not seem very useful at first, but using (.) as the name of the current directory will save a lot of typing, as we shall see later in the tutorial.
(..) means the parent of the current directory, so typing
compsci-user@tim:~$ cd ..
will take you one directory up the hierarchy (back to your home directory). Try it now.
Pathnames enable you to work out where you are in relation to the whole file-system. For example, to find out the absolute pathname of your home-directory, type cd to get back to your home-directory and then type
The full pathname will look something like this -
which means that compsci-user (your home directory) which is in the home sub-directory, which is in the top-level root directory called “ / ” .
Use the commands cd, ls and pwd to explore the file system.
(Remember, if you get lost, type cd by itself to return to your home-directory)
First type cd to get back to your home-directory, then type
compsci-user@tim:~$ ls testdir
to list the contents of your testdir directory.
compsci-user@tim:~$ ls backups
The reason is, backups is not in your current working directory. To use a command on a file (or directory) not in the current working directory (the directory you are currently in), you must either cd to the correct directory, or specify its full pathname. To list the contents of your backups directory, you must type
compsci-user@tim:~$ ls testdir/backups
Home directories can also be referred to by the tilde ~ character. It can be used to specify paths starting at your home directory. So typing
compsci-user@tim:~$ ls ~/testdir
will list the contents of your unixstuff directory, no matter where you currently are in the file system.
What do you think
compsci-user@tim:~$ ls ~
What do you think
compsci-user@tim:~$ ls ~/..
|ls||list files and directories|
|ls -a||list all files and directories|
|mkdir||make a directory|
|cd directory||change to named directory|
|cd||change to home-directory|
|cd ~||change to home-directory|
|cd ..||change to parent directory|
|pwd||display the path of the current directory|