1: Working with Folders

These commands allow you to change read-write and access permissions for files, and change their locations in Directories (Folders)

Before diving into the linux commands lets look at the directory structure from the file manager on the Pi desktop

Figure \(\PageIndex{1}\):Directory structure as seen by file manager. (Belford cc 0.0)

 

In this activity we are going to assume you have started your Pi and are in your user directory

pwd - Print Working Directory

Identifies Current Directory

 rebelford@raspberrypi:~ $ pwd

pwd

Output:

 

ls - List Directory Content

With the last command, we created two new subdirectories. We can look at the list with the command:

• ls : list

ls

Output:

 

ls switches

ls
ls /home/pi
ls -1     (one, to make a single column)
ls -l      (long, to list info)
ls -l -a   (long and all, to include hidden files
ls ../   (reaches up one level)

mkdir - Create Directory

In this section, we will learn how to create new files to work with. To avoid any accidental changes that we can make to our existing files, we will start by creating a new directory, not located in the home folder. 

To create a new directory named "tmp" use the command:

• mkdir :  make directory

First we will list what is in the directory, then make the new directory and then print it out to see that it is th

We can start create multiple directories at once

mkdir subdir1 subdir2

 

ls
mkdir tmp
ls

Output:

• We will now make three new subdirectories, and then list the content

mkdir sub1 sub2 sub3

Output:

 

cd - Change Directory

cd <path> directs to a specific directory in the tree

note, there must be a space after the cd

 

We will first list the files where we are, move to tmp and then print the current (working) directory

ls
cd tmp
pwd

Output:

 

cd switches

the following switches work on cd

cd /home/pi
cd   #by itself takes you home
cd ~  navigate to home directory
cd /  navigate to root directory
cd .. go up one level
cd - go back one level

 

 

Lets go to the root directory and list the content. We note there is another directory called root there, so lets list its content.  What we notice is we have two directories with the same name, but in different place in the file tree.

ls
cd /
ls
cd tmp ls

Output:

Lets go home

 

you can always return to the home directory with the ~ switch. Here show we are in the tmp in root, go home, and then move to the tmp we just created and show we are there

pwd
cd ~ 
pwd
cd tmp
pwd

Output:

 

rm - Remove Directory

for empty directories

rm -d directory_name

for directories with files in them (-r is recursive, and removes contents of directory)

rm -r directory-name

The -r is a switch making the command recursive

to do it without asking for confirmation 

rm -rf directory_name 

The -f switch "forces" the action

BE VERY CAREFUL WHEN USING  rm -r or rm -rf as you delete everything, including subfolders.

 

In this activity we will go back to our user directory and remove the tmp folder we made, and then show it is gone

cd ..
ls
rm -r tmp
ls

Output:

 

 

In this activity we list the files in the user directory, then in one command remove the three sub directories we had earlier made, and then show they are gone

ls
rm -r sub1 sub2 sub3
ls

Output:

 

The mkdir can not be used on its own (like the previous command cd or pwd). It is always followed by parameters. 

The mkdir command expects to have at least one parameter

The cd command can use zero or one parameter at maximum

 

cp - Copying directories

We can copy a directory to a new location by using the command: 

• cp    directory_name    destination :  Copies directory (or file) to a new location

Note

To include the subfolders of a directory, we need to add -r (recursive)

cp /tmp/test/subdir2 /tmp/test/subdir1 -r
cd subdir1
ls

Output:

Relative and Absolute paths

Relative path

The previous examples that we worked on used some relative paths. Working with a relative path means that the place where you go depends on your current working directory.

The "etc" directory is a file that is located directly inside the root of the file system. If you were to try and cd to the "etc" folder while you are in the root directory, it will work.

cd /
pwd
cd etc 
pwd      

However, if you are not in your root directory, that won't work.

cd
pwd
cd etc
pwd     

You will get an error saying "No such file or directory". 

Changing the working directory will affect where you start. The path of the directory you want to access only makes sense while it is relative to your working directory.

 

Absolute path

Absolute commands have the same effect no matter what your current working directory is. From our previous examples, the cd command is an absolute one. When you run it on its own, you go straight to your home directory. Another previous example is the cd / command. It directly switches you to the root directory when you run it on its own.

Note: Any path starting with / is an absolute path. When you want to switch to a directory and start your path with the /, it is the equivalent of "going to the root directory and then to the folder that comes after the slash". 

cd
pwd
cd /etc     
pwd

find 

find works on both directories and files.

tree