An Introduction to the Linux Command line for Beginners

An Introduction to the Linux Command line for Beginners

I mentioned in my last blog post that I will be learning in public and sharing what I learn online in order to hold myself accountable and measure my progress.

Well last month, I learned how to use the Linux command line. Here's some background information on that. In that post, I explained that I am currently curating my coding studies with The Odin Project (TOP) curriculum. TOP encourages students to use a Linux system to learn coding, while those of us with a windows computer are taught how to access Ubuntu through a virtual machine. After installing the virtual machine, we then explored how to manipulate the command line.

My usual practice whenever I'm studying or learning something new is to jot down useful and relevant notes in a notebook. However, for the purpose of this learning-in-public journey, I have chosen to share my notes below πŸ‘‡

Linux File System Operations

Manipulating files and directories

  • to create a new directory type πŸ‘‰ mkdir <directoryname>. To create intermediate or nested directories, the mkdir command will allow you to do so using the -p flag like this πŸ‘‰ mkdir -p Documents/book/page.

  • to create a file, use πŸ‘‰ touch <filename(s)>. For example, to create a single file, type πŸ‘‰ touch novel.txt and touch letter.doc index.html script.js style.css to create multiple files at once.

  • to copy a file, use the cp command citing two arguments; the first argument is the file you want to copy (the source file) while the second argument (or target) is the location you want to copy the source file to. For instance, type πŸ‘‰ cp letter.doc book.doc. When copying one directory to another, use the -r flag and specify both the source and target directories' paths. To copy only the contents of a directory, remember to use the star * operator at the end of the source directory path e.g cp ~/book/* ~/Documents.

  • to delete directories, use rmdir <directory name> or rm -d <directory name> and rm -r <directory name> or rm -rf <directory name> for empty and non-empty directories respectively. To delete a file, type πŸ‘‰ rm <filename> e.g, rm script.js. To confirm that a command is about to be executed use the -i flag, for instance to confirm that a file is about to be overwritten, type πŸ‘‰ cp -i <originfile> <targetfile>.

  • to rename or move a file (or directory), use the mv command and type πŸ‘‰ mv <oldname> <newname> for instance mv book.doc index.html to rename a file or mv <directoryname> <targetdirectory> to move a directory. You can also move a file or directory by first using the cp and then therm commands. Remember to use the -r flag when copying directories. To move or copy a file to the current directory, specify the path/location of the file followed by . (which means the 'current directory') for instance type πŸ‘‰ cp ~/book/page.txt .

  • to print the results of a command to the console, add the -v flag. e.g, rm -v book.doc. Using this flag can provide useful reporting when writing scripts that will execute a lot of commands for you.

Note: most command line programs support tab completion, which involves automatically completing a word if there's only one valid match on the system. For example, if the only file starting with the letters 'Pic' is Picture, you could create the command to remove it as follows πŸ‘‰ rm Picβ‡₯ where β‡₯ is the tab key. The program would then complete the filename, yielding rm Picture. This feature is especially handy with longer filenames (or directories) where tab completion can save a huge amount of typing.

Navigating Directories and Files

  • to find out where you are on the terminal, use the pwd command. You can also use this to get the path of your home directory. To see if a given program is available at the command line, type πŸ‘‰ which <program name>. The which command technically locates a file on the user’s [usr] path; which is a list of directories where executable programs are located.

  • to see what files or directories are in your current directories, type ls. To see both 'visible' and 'hidden' files and directories, use the -a flag as follows πŸ‘‰ ls -a. To find out the contents of another directory, without first leaving your current directory, specify the full path of the other directory to the ls command as follows πŸ‘‰ ls /home/username/Documents/novel. To list directories' names only without listing their contents use the -d flag, for instance type πŸ‘‰ ls -d txt* to list all files and directories starting with txt without listing their contents.

  • to list all files and directories of a certain type for instance; for all files ending in txt pattern, type πŸ‘‰ ls *txt; for all files starting with txt, type πŸ‘‰ ls txt*; for all files containing txt, type πŸ‘‰ ls *txt*. To find files whose names match a certain pattern or file extension e.g .txt starting in the current directory . and in its sub-directories, use the find command and type πŸ‘‰ find . -name '*.txt'.

  • to find out detailed information on files and directories, type πŸ‘‰ ls -l. To see the sizes of files and directories, in human readable format such as 1K or 23M, use πŸ‘‰ ls -lh. To list the long form of each file or directory in order of how recently it was modified (reversed so that the most recently modified entries appear at the bottom of the screen for easy inspection), type πŸ‘‰ ls -lrt. To display the long form of files sorted so the largest files appear at the bottom, type πŸ‘‰ ls -lrS.

  • to navigate to the home directory, simply type πŸ‘‰ cd. To navigate back up a directory (i.e to move one level up to the parent directory of the current directory) type πŸ‘‰ cd .. To move change directories to the previous directory, wherever that was, type πŸ‘‰ cd -. To move to an immediate sub-directory, type πŸ‘‰ cd <directory> e.g cd Documents. To simply change directories, call the cd command by specifying to it the full path of the directory you want to navigate to e.g, cd ~/book.

  • to redirect the output of one command to the input of another command, use the pipe operator |. For instance, to interactively navigate the full output of a command like git help in your terminal window, pipe the output to less as follows πŸ‘‰ git help | less.

  • to combine commands, use the semicolon ; or double-ampersand && characters after each command you want to combine e.g. to create a file in another directory without leaving your current directory, type πŸ‘‰cd <directory> && touch <filename> && cd -. The difference between these two characters is that commands separated by && run only if the previous command succeeded while with ; all the commands will be run no matter what.

Hey, thanks for reading!

Bye for now πŸ‘‹ πŸ‘‹