day12.md

On the twelveth day, I learned the following things about Linux.

• The command line interface will communicate with the kernel and it will give the input to the kernel to do a certain task and as a result the kernel will perform that operation.

• In the command prompt, the path will be given to you that has two parts.

  1. The first is the user part and

  2. the second is the host part. In between them, there is a separater "@"

• where filename will show you the list of directories in which a file is present.

• open . will open all the files present in a specific directory.

• echo $PATH When one types a command to run, the system looks for it in the directories specified by PATH. It will display the files and folders paths by the difference of colon : It will check the executable command in one of these paths.

• echo "Hey" > file.txt will override the text in a file.

• echo "Hey" >> file.txt will append the text in a file.

• export MY_PATH="Bilal" will create another path that will contain the string. But this is not permanent

• pwd will show the present working directory in which you're currently present.

• ls will show you the list of all the files present in a specific directory.

• ls -a will show you the list of all the hidden files present in a specific directory. Hidden files are starting from dot .

• ls -l will show you the list of files with long details present in a specific directory.

• ls -la will show you the list of more files including hidden files with long details present in a specific directory.

• ls -R will find all the folders and sub folders and so on recursively.

• Dot . means current directory, .. double dot means previous directory.

• cd (change directory) will change the path location from one directory to another.

• cat filename (concatenate) will print all the content of a file in a standard output.

• cat > filename will create a new file if it is not present and allow us to enter the text also.

• tr will translate the characters from one string to another string.

• cat lower.txt | tr a-z A-Z > upper.txt, the output of the first command is the input of the second command.

• man command-name will show you the details of a specific command.

• mkdir directory-name will create a new directory.

• mkdir -p random/middle/hello will create a middle directory b/w two directories. -p is used for parent's command.

• touch filename will create a new file.

• cp file.txt copy_file.txt will make a copy of the file.txt

• cp -R test random will copy the test directory into the random directory.

• mv file.txt random will move the file.txt to the random folder.

• mv file.txt new_file.txt will rename the file.txt to new_file.txt.

• mv test renamedTest will rename the directory.

• rm file.txt will remove a file from your computer permanently.

• rm -R directory-name will remove the directory recursively.

• rm -rf directory-name will forcefully remove the directory.

Explaining it in a video

Here you can get an explanation in a video. 12/60 Day of DevOps Challenge