Basic Commands

cd

Usage
- To change directories
Examples

cd temp # browses to the directory called temp
cd /usr/bin # browses to /usr/bin folder
cd - # browse to previous directory
cd .. # browse to the parent direcotry
cd ../../ #browse 2 parent directories behind

pwd

Usage
- To print current working directory

Examples

pwd # simply lists the current folder you are in

ls

Usage
- To list all the files and directories
Examples
```
ls # lists current directory
ls -l # list current directory with details
ls -a # list all the hidden files
ls -R # list recursively
```
<p class="callout info">Please note, you can combine a number of the switches in one query rather than running them one by one. e.g. ls -lah</p>

mkdir

Usage
- to create a new directory

Examples

mkdir directory #create a folder with the name directory
mkidr -p directory/data #create a folder with a subfolder called data

cp

Usage
- Copy a file from one place to another

Examples

cp hash /temp #copies file into the specified folder
cp hash hash1 #copies the content of a file into a different one
cp -r folder1/ folder2/ #copies the folder with it's content into a folder called folder2

mv

Usage
- To move a file from one place to another, also can be used to rename a file.

Examples

mv file1 ../ #moves the file from the current folder to the parent folder
mv file1 file2 #renames file1 to file2

touch

Usage
- To create an empty file.

Examples

touch file1 #create file 1
touch hash && echo "some_text" > hash # create a file cat hash and write in the file the words "some_text"

cat/tac

Usage
- To read the content of a file.

Examples

cat hash # read the content of the file called hash
tac hash # same as above

rm

Usage

To remove a file or folder.

Examples

rm file1 # remove file1
rm -rf folder1 # recursively remove the content of folder1 and discard any files in use.

grep

Usage

Search for a line or specific text in a file.
Examples
```
grep "text" file_with_text.txt # Print all lines that have the word "text"
grep -c "text" file_with_text.txt # Count the number of occurences of the word "text"
grep -i "text" file_with_text #Print all lines that contain the case insensitive word "text"
```
The grep function has a ton of use cases, it can do regex matches, show lines before or after specific text and a lot more. I would advise to read the manual pages for more use cases. See the below URL for more information on the command: GNU Grep 3.7

head

Usage
- Read the first n lines of a file.

Examples

head file.txt # Default behaviour is to output the first 10 lines of a file
head -n 3 # Output the first 3 lines of a file

tail

Usage
- Read the last n lines of a file

Examples

tail file.txt # Default behaviour, output the last 10 lines of a file
tail -n 3 # Output the last 3 lines of a file

chmod

Usage
- To change the permissions of a file or folder

Examples

chmod +x file1 # make a specific file executable
chmod 754 file1 # grant the file read, write, execute to user, read and execute to group and read to other

echo

Usage
- To write something in the console or file.

Examples

echo "Some really interesting text" #write the test between brackets

clear

Usage
- To clear the terminal windows of text.
Examples
```
clear # clears the terminal window
```

sudo

Usage
- To escalate your privileges to super user.

Examples

sudo ./script.sh # execute the script as root
sudo apt install memes # escalate your privileges to install the application called memes