working with linux directories

This module is a brief overview of the most common commands to work with directories: pwd, cd, ls, mkdir and rmdir. These commands are available on any Linux (or Unix) system.

pwd

The you are here sign can be displayed with the pwd command (Print Working Directory). Go ahead, try it: Open a command line interface (also called a terminal, console or xterm) and type pwd. The tool displays your current directory.
kick@centos:~$ pwd
/home/paul

cd

You can change your current directory with the cd command (Change Directory).

kick@centos$: cd /etc
kick@centos$: pwd
/etc

kick@centos$: cd /bin
kick@centos$: pwd
/bin
kick@centos$: cd /home/paul/
kick@centos$: pwd
/home/centos

cd ~

The cd is also a shortcut to get back into your home directory. Just typing cd without a target directory, will put you in your home directory. Typing cd ~ has the same effect.
kick@debian8$: cd /etc
kick@debian8$:pwd
/etc

kick@debian8$: cd
kick@debian8$: pwd
/home/paul
kick@debian8$: cd ~
kick@debian8$: pwd
/home/paul

cd ..

To go to the parent directory (the one just above your current directory in the directory tree), type cd .. .
kick@centos$: pwd
/usr/share/games
kick@centos$: cd ..
kick@centos$: pwd
/usr/share

cd –

Another useful shortcut with cd is to just type cd – to go to the previous directory.
kick@centos$: pwd
/home/paul
kick@centos$: cd /etc
kick@centos$:pwd
/etc
kick@centos$: cd –
/home/paul
kick@centos$: cd –
/etc

absolute and relative paths

You should be aware of absolute and relative paths in the file tree. When you type a path starting with a slash (/), then the root of the file tree is assumed. If you don’t start your path with a slash, then the current directory is the assumed starting point.

first shows the current directory /home/paul. From within this directory, you have to type cd /home instead of cd home to go to the /home directory.

kick@centos$: pwd
/home/paul
kick@centos$: cd home
bash: cd: home: No such file or directory
kick@centos$: cd /home
kick@centos$: pwd
/home

When inside /home, you have to type cd paul instead of cd /paul to enter the subdirectory paul of the current directory /home.

kick@centos$: pwd
/home
kick@centos$: cd /kick
bash: cd: /paul: No such file or directory
kick@centos$: cd kick
kick@centos$: pwd
/home/paul

In case your current directory is the root directory /, then both cd /home and cd home will get you in the /home directory.
kick@centos$: pwd
/
kick@centos$: cd home
kick@centos$: pwd
/home
kick@cenyos$: cd /
kick@centos$: cd /home
kick@centos$: pw
/home

path completion

The tab key can help you in typing a path without errors. Typing cd /et followed by the tab key will expand the command line to cd /etc/. When typing cd /Et followed by the tab key, nothing will happen because you typed the wrong path (upper case E).

You will need fewer key strokes when using the tab key, and you will be sure your typed path is correct!

ls

You can list the contents of a directory with ls.

ls

ls -a

A frequently used option with ls is -a to show all files. Showing all files means including the hidden files. When a file name on a Linux file system starts with a dot, it is considered a hidden file and it doesn’t show up in regular file listings.

ls -a

ls -l

Many times you will be using options with ls to display the contents of the directory in different formats or to display different parts of the directory. Typing just ls gives you a list of files in the directory. Typing ls -l (that is a letter L, not the number 1) gives you a long listing.

ls -l

ls -lh

Another frequently used ls option is -h. It shows the numbers (file sizes) in a more human readable format. Also shown below is some variation in the way you can give the options to ls.

ls -lh

mkdir

Walking around the Unix file tree is fun, but it is even more fun to create your own directories with mkdir. You have to give at least one parameter to mkdir, the name of the new directory to be created. Think before you type a leading / .

mkdir

rmdir

When a directory is empty, you can use rmdir to remove the directory.

rmdir

practice: working with directories

1. Display your current directory.
2. Change to the /etc directory.
3. Now change to your home directory using only three key presses.
4. Change to the /boot/grub directory using only eleven key presses.
5. Go to the parent directory of the current directory.
6. Go to the root directory.
7. List the contents of the root directory.
8. List a long listing of the root directory.
9. Stay where you are, and list the contents of /etc.
10. Stay where you are, and list the contents of /bin and /sbin.
11. Stay where you are, and list the contents of ~.
12. List all the files (including hidden files) in your home directory.
13. List the files in /boot in a human readable format.
14. Create a directory testdir in your home directory.
15. Change to the /etc directory, stay here and create a directory newdir in your home directory.
16. Create in one command the directories ~/dir1/dir2/dir3 (dir3 is a subdirectory from dir2, and dir2 is a subdirectory from dir1 ).
17. Remove the directory testdir.
18. If time permits (or if you are waiting for other students to finish this practice), use and understand pushd and popd. Use the man page of bash to find information about these commands.

solution: working with directories

1. Display your current directory.
pwd
2. Change to the /etc directory.
cd /etc
3. Now change to your home directory using only three key presses.
cd (and the enter key)
4. Change to the /boot/grub directory using only eleven key presses.
cd /boot/grub (use the tab key)
5. Go to the parent directory of the current directory.
cd .. (with space between cd and ..)
6. Go to the root directory.
cd /
7. List the contents of the root directory.
ls
8. List a long listing of the root directory.
ls -l
9. Stay where you are, and list the contents of /etc.
ls /etc
10. Stay where you are, and list the contents of /bin and /sbin.
ls /bin /sbin
11. Stay where you are, and list the contents of ~.
ls ~
12. List all the files (including hidden files) in your home directory.
ls -al ~
13. List the files in /boot in a human readable format.
ls -lh /boot
14. Create a directory testdir in your home directory.
mkdir ~/testdir
15. Change to the /etc directory, stay here and create a directory newdir in your home directory.

cd /etc ; mkdir ~/newdir
16. Create in one command the directories ~/dir1/dir2/dir3 (dir3 is a subdirectory from dir2, and dir2 is a subdirectory from dir1 ).
mkdir -p ~/dir1/dir2/dir3
17. Remove the directory testdir.
rmdir testdir
18. If time permits (or if you are waiting for other students to finish this practice), use and understand pushd and popd. Use the man page of bash to find information about these commands.
man bash
/pushd
n
# opens the manual
# searches for pushd
# next (do this two/three times)

The Bash shell has two built-in commands called pushd and popd. Both commands work with a common stack of previous directories. Pushd adds a directory to the stack and changes to a new current directory, popd removes a directory from the stack and sets the current directory.
kick@centos:/etc$ cd /bin
kick@centos:/bin$ pushd /lib
/lib /bin
kick@centos:/lib$ pushd /proc
/proc /lib /bin
kick@centos:/proc$ popd
/lib /bin
kick@centos:/lib$ popd
/bin

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