Simple File System Manipulation

Filesystem Structure

In Linux the file system is structured like a tree. As all classical trees in computer science the root sits at the top and the branches are at the bottom. The sharp observer will note that this is contrary to the way this is done by nature as can be observed while taking a walk through a park.

/ denotes the root of the tree.

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Run ls / to see the first set of nodes located directly under the root.

Be aware that in Linux everything is a file. This also holds true for directories and even hardware devices. This simple concept enables some incredibly powerful interaction concepts.

The home directory

There is no place like home. The home directory might be a confusing term for new Linux users. Contrary to intuition it does not refer to the directory /home but rather to the directory that you as user have full control over, that is YOUR home directory.

Your home directory is a sub-directory in the directory /home and is named identical to your user. If your username is john then your home directory is located at /home/john. The shorthand ~ or more precisely ~username can be used to reference a home directory. For John ~ will expand to ~john and cd ~ will take you home.

Basic orientation and movement

Command	Meaning
pwd	prints the path of the current working directory
cd	changes the directory
.	denotes the current directory
..	denotes the parent of the current working directory

ls

The ls command as you might already have guessed is used to list the content of a directory

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Look it up in the man pages to learn more.

Copying files

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Explore the cp command. Check how you can avoid overwriting files during copy and how you can copy directories.

Moving files

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Explore the mv command. Figure out how to rename files, move directories and avoid overwriting targets.

Creating and deleting files

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Find a command to create an empty file and how you can create a file containing some simple text without using an editor. Delete the files you just created.

Creating and deleting directories

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Create a directory, add a file to it and delete it without separately deleting the file first.

Finding Files

One of the bigger challenges of a file system user is usually finding stuff. Linux offers a very handy command for helping with this issue

find [starting dir] [search options] [criteria] [result options]

for example

 find /etc -name hosts

will find all files named hosts in /etc usually you would write find /etc -name hosts 2> /dev/null what this does will be explained later 😃

Another example would be

find /etc -size 10c -ls 2>/dev/null

This will return all files in /etc that are exactly 10 bytes (10c) and return them as list with details.

Here are some useful search options for you:

Option	Meaning
-maxdepth	How deep to search the directory tree
-group	Find files belonging to this group (more on groups later)
-user	Find files belonging to a specific user
-iname	case insensitive name search
-mmin	Find files based on last modified in minutes
-type	Find files of a specific type