There’s one thing about Linux that corporations like Microsoft, Apple, and Google will never be able to offer: the freedom to do whatever you want with your computer.<\/p>\n\n\n\n
Linux is also special because there’s not just “one Linux”, like is the case with Windows or macOS. Instead, we have distributions<\/strong>.<\/p>\n\n\n\n A “distro” is made by a company or organization and packages the Linux core with additional programs and tooling.<\/p>\n\n\n\n For example you have Debian, Red Hat, and Ubuntu, probably the most popular distributions.<\/p>\n\n\n\n A shell is a command interpreter that exposes an interface to the user to work with the underlying operating system.<\/p>\n\n\n\n It allows you to execute operations using text and commands, and it provides users advanced features like being able to create scripts.<\/p>\n\n\n\n This is important: shells let you perform things in a more optimized way than a GUI (Graphical User Interface) could ever possibly let you do. Command line tools can offer many different configuration options without being too complex to use.<\/p>\n\n\n\n There are many different kind of shells. This post focuses on Unix shells, the ones that you will find commonly on Linux and macOS computers.<\/p>\n\n\n\n Many different kind of shells were created for those systems over time, and a few of them dominate the space: Bash, Csh, Zsh, Fish and many more!<\/p>\n\n\n\n All shells originate from the Bourne Shell, called Bash means Bourne-again shell<\/em>. If you use a Mac, try opening your Mac terminal. By default it runs ZSH (or, pre-Catalina, Bash).<\/p>\n\n\n\n You can set up your system to run any kind of shell \u2013 for example I use the Fish shell.<\/p>\n\n\n\n Each single shell has its own unique features and advanced usage, but they all share a common functionality: they can let you execute programs, and they can be programmed.<\/p>\n\n\n\n In the rest of this handbook we’ll see in detail the most common commands you will use.<\/p>\n\n\n\n Every time I don’t know how to use a command, I type This is a man (from _manual_<\/em>) page. Man pages are an essential tool to learn as a developer. They contain so much information that sometimes it’s almost too much. Most of the time when I need to learn a command quickly I use this site called tldr pages<\/strong>: https:\/\/tldr.sh<\/a>. It’s a command you can install, which you then run like this: Inside a folder you can list all the files that the folder contains using the If you add a folder name or path, it will print that folder’s contents:<\/p>\n\n\n\n Compared to the plain You have, from left to right:<\/p>\n\n\n\n This set of data is generated by the Hidden files are files that start with a dot ( Once you have a folder, you can move into it using the Example:<\/p>\n\n\n\n Now you are in the You can use the The # character indicates the start of the comment, which lasts for the entire line after it’s found.<\/p>\n\n\n\n You can use it to form a path:<\/p>\n\n\n\n There is another special path indicator which is You can also use absolute paths, which start from the root folder Whenever you feel lost in the filesystem, call the It will print the current folder path.<\/p>\n\n\n\n You create folders using the You can create multiple folders with one command:<\/p>\n\n\n\n You can also create multiple nested folders by adding the Options in UNIX commands commonly take this form. You add them right after the command name, and they change how the command behaves. You can often combine multiple options, too.<\/p>\n\n\n\n You can find which options a command supports by typing Just as you can create a folder using You can also delete multiple folders at once:<\/p>\n\n\n\n The folder you delete must be empty.<\/p>\n\n\n\n To delete folders with files in them, we’ll use the more generic Be careful as this command does not ask for confirmation and it will immediately remove anything you ask it to remove.<\/p>\n\n\n\n There is no bin<\/strong> when removing files from the command line, and recovering lost files can be hard.<\/p>\n\n\n\n Once you have a file, you can move it around using the The If the last parameter is a folder, the file located at the first parameter path is going to be moved into that folder. In this case, you can specify a list of files and they will all be moved in the folder path identified by the last parameter:<\/p>\n\n\n\n You can copy a file using the To copy folders you need to add the The You can also open a directory, which on macOS opens the Finder app with the current directory open:<\/p>\n\n\n\n I use it all the time to open the current directory:<\/p>\n\n\n\n The special The same command can also be be used to run an application:<\/p>\n\n\n\n You can create an empty file using the If the file already exists, it opens the file in write mode, and the timestamp of the file is updated.<\/p>\n\n\n\n The Let’s learn how to use it by example.<\/p>\n\n\n\n Find all the files under the current tree that have the It’s important to use quotes around special characters like Find directories under the current tree matching the name “src”:<\/p>\n\n\n\n Use You can search under multiple root trees:<\/p>\n\n\n\n Find directories under the current tree matching the name “node_modules” or ‘public’:<\/p>\n\n\n\n You can also exclude a path using You can search files that have more than 100 characters (bytes) in them:<\/p>\n\n\n\n Search files bigger than 100KB but smaller than 1MB:<\/p>\n\n\n\n Search files edited more than 3 days ago:<\/p>\n\n\n\n Search files edited in the last 24 hours:<\/p>\n\n\n\n You can delete all the files matching a search by adding the You can execute a command on each result of the search. In this example we run Notice the terminating The It’s used to create links. What is a link? It’s like a pointer to another file, or a file that points to another file. You might be familiar with Windows shortcuts. They’re similar.<\/p>\n\n\n\n We have 2 types of links: hard links<\/strong> and soft links<\/strong>.<\/p>\n\n\n\n Hard links are rarely used. They have a few limitations: you can’t link to directories, and you can’t link to external filesystems (disks).<\/p>\n\n\n\n A hard link is created using the following syntax:<\/p>\n\n\n\n For example, say you have a file called recipes.txt. You can create a hard link to it using:<\/p>\n\n\n\n The new hard link you created is indistinguishable from a regular file:<\/p>\n\n\n\n Now any time you edit any of those files, the content will be updated for both.<\/p>\n\n\n\n If you delete the original file, the link will still contain the original file content, as that’s not removed until there is one hard link pointing to it.<\/p>\n\n\n\n Soft links are different. They are more powerful as you can link to other filesystems and to directories. But keep in mind that when the original is removed, the link will be broken.<\/p>\n\n\n\n You create soft links using the For example, say you have a file called recipes.txt. You can create a soft link to it using:<\/p>\n\n\n\n In this case you can see there’s a special You can compress a file using the gzip compression protocol named LZ77<\/a> using the Here’s the simplest usage:<\/p>\n\n\n\n This will compress the file, and append a To prevent this, you can use the What is a Linux shell?<\/h4>\n\n\n\n
sh<\/code>. “Bourne” because its creator was Steve Bourne<\/strong>.<\/p>\n\n\n\nsh<\/span><\/code> was proprietary and not open source, and Bash was created in 1989 to create a free alternative for the GNU project and the Free Software Foundation. Since projects had to pay to use the Bourne shell, Bash became very popular.<\/p>\n\n\n\nThe Linux
man<\/code> <\/span>command<\/h4>\n\n\n\nman <command><\/code> to get the manual:<\/p>\n\n\n\n![\"\"](\"https:\/\/www.freecodecamp.org\/news\/content\/images\/2020\/10\/Screen-Shot-2020-07-04-at-18.42.40.png\")
<\/figure>\n\n\n\n
The above screenshot is just 1 of 14 screens of explanation for the ls<\/code> command.<\/p>\n\n\n\ntldr <command><\/code>. It gives you a very quick overview of a command, with some handy examples of common usage scenarios:<\/p>\n\n\n\n![\"\"\/](\"https:\/\/www.freecodecamp.org\/news\/content\/images\/2020\/10\/Screen-Shot-2020-09-07-at-07.35.41.png\")
<\/figure>\n\n\n\nThe Linux
ls<\/span><\/code> command<\/h4>\n\n\n\nls<\/code> command:<\/p>\n\n\n\nls<\/code><\/pre>\n\n\n\nls \/bin<\/code><\/pre>\n\n\n\n![\"Screenshot-2019-02-09-at-18.50.14\"\/](\"https:\/\/www.freecodecamp.org\/news\/content\/images\/2020\/10\/Screenshot-2019-02-09-at-18.50.14.png\")
<\/figure>\n\n\n\nls<\/code> accepts a lot of options. One of my favorite combinations is -al<\/code>. Try it:<\/p>\n\n\n\nls -al \/bin\n<\/code><\/pre>\n\n\n\n![\"Screenshot-2019-02-09-at-18.49.52\"\/](\"https:\/\/www.freecodecamp.org\/news\/content\/images\/2020\/10\/Screenshot-2019-02-09-at-18.49.52.png\")
<\/figure>\n\n\n\nls<\/code> command, this returns much more information.<\/p>\n\n\n\nl<\/code> option. The a<\/code> option instead also shows the hidden files.<\/p>\n\n\n\n.<\/code>).<\/p>\n\n\n\nThe Linux
cd<\/code> <\/span>command<\/h4>\n\n\n\ncd<\/code> command. cd<\/code> means c<\/strong>hange d<\/strong>irectory. You invoke it specifying a folder to move into. You can specify a folder name, or an entire path.<\/p>\n\n\n\nmkdir fruits\ncd fruits\n<\/code><\/pre>\n\n\n\nfruits<\/code> folder.<\/p>\n\n\n\n..<\/code> special path to indicate the parent folder:<\/p>\n\n\n\ncd .. #back to the home folder\n<\/code><\/pre>\n\n\n\nmkdir fruits\nmkdir cars\ncd fruits\ncd ..\/cars\n<\/code><\/pre>\n\n\n\n.<\/code>, and indicates the current<\/strong> folder.<\/p>\n\n\n\n\/<\/code>:<\/p>\n\n\n\ncd \/etc\n<\/code><\/pre>\n\n\n\nThe Linux
pwd<\/span><\/code> command<\/h4>\n\n\n\npwd<\/code> command to know where you are:<\/p>\n\n\n\npwd\n<\/code><\/pre>\n\n\n\nThe Linux
mkdir<\/span><\/code> command<\/h4>\n\n\n\nmkdir<\/code> command:<\/p>\n\n\n\nmkdir fruits\n<\/code><\/pre>\n\n\n\nmkdir dogs cars\n<\/code><\/pre>\n\n\n\n-p<\/code> option:<\/p>\n\n\n\nmkdir -p fruits\/apples\n<\/code><\/pre>\n\n\n\nman <commandname><\/code>. Try now with man mkdir<\/code> for example (press the q<\/code> key to esc the man page). Man pages are the amazing built-in help for UNIX.<\/p>\n\n\n\nThe Linux
rmdir<\/code><\/span> command<\/h4>\n\n\n\nmkdir<\/code>, you can delete a folder using rmdir<\/code>:<\/p>\n\n\n\nmkdir fruits\nrmdir fruits\n<\/code><\/pre>\n\n\n\nmkdir fruits cars\nrmdir fruits cars\n<\/code><\/pre>\n\n\n\nrm<\/code> command which deletes files and folders, using the -rf<\/code> option:<\/p>\n\n\n\nrm -rf fruits cars\n<\/code><\/pre>\n\n\n\nThe Linux
mv<\/code> <\/span>command<\/h4>\n\n\n\nmv<\/code> command. You specify the file current path, and its new path:<\/p>\n\n\n\ntouch test\nmv pear new_pear\n<\/code><\/pre>\n\n\n\npear<\/code> file is now moved to new_pear<\/code>. This is how you rename<\/strong> files and folders.<\/p>\n\n\n\ntouch pear\ntouch apple\nmkdir fruits\nmv pear apple fruits #pear and apple moved to the fruits folder\n<\/code><\/pre>\n\n\n\nThe Linux
cp<\/span><\/code> command<\/h4>\n\n\n\ncp<\/code> command:<\/p>\n\n\n\ntouch test\ncp apple another_apple\n<\/code><\/pre>\n\n\n\n-r<\/code> option to recursively copy the whole folder contents:<\/p>\n\n\n\nmkdir fruits\ncp -r fruits cars\n<\/code><\/pre>\n\n\n\nThe Linux
open<\/span><\/code> command<\/h4>\n\n\n\nopen<\/code> command lets you open a file using this syntax:<\/p>\n\n\n\nopen <filename>\n<\/code><\/pre>\n\n\n\nopen <directory name>\n<\/code><\/pre>\n\n\n\nopen .\n<\/code><\/pre>\n\n\n\n.<\/code> symbol points to the current directory, as ..<\/code> points to the parent directory<\/p><\/blockquote>\n\n\n\nopen <application name>\n<\/code><\/pre>\n\n\n\nThe Linux
touch<\/span><\/code> command<\/h4>\n\n\n\ntouch<\/code> command:<\/p>\n\n\n\ntouch apple\n<\/code><\/pre>\n\n\n\nThe Linux
find<\/code> <\/span>command<\/h4>\n\n\n\nfind<\/code> command can be used to find files or folders matching a particular search pattern. It searches recursively.<\/p>\n\n\n\n.js<\/code> extension and print the relative path of each file that matches:<\/p>\n\n\n\nfind . -name '*.js'\n<\/code><\/pre>\n\n\n\n*<\/code> to avoid the shell interpreting them.<\/p>\n\n\n\nfind . -type d -name src\n<\/code><\/pre>\n\n\n\n-type f<\/code> to search only files, or -type l<\/code> to only search symbolic links.<\/p>\n\n\n\n-name<\/code> is case sensitive. use -iname<\/code> to perform a case-insensitive search.<\/p>\n\n\n\nfind folder1 folder2 -name filename.txt\n<\/code><\/pre>\n\n\n\nfind . -type d -name node_modules -or -name public\n<\/code><\/pre>\n\n\n\n-not -path<\/code>:<\/p>\n\n\n\nfind . -type d -name '*.md' -not -path 'node_modules\/*'\n<\/code><\/pre>\n\n\n\nfind . -type f -size +100c\n<\/code><\/pre>\n\n\n\nfind . -type f -size +100k -size -1M\n<\/code><\/pre>\n\n\n\nfind . -type f -mtime +3\n<\/code><\/pre>\n\n\n\nfind . -type f -mtime -1\n<\/code><\/pre>\n\n\n\n-delete<\/code> option. This deletes all the files edited in the last 24 hours:<\/p>\n\n\n\nfind . -type f -mtime -1 -delete\n<\/code><\/pre>\n\n\n\ncat<\/code> to print the file content:<\/p>\n\n\n\nfind . -type f -exec cat {} \\;\n<\/code><\/pre>\n\n\n\n\\;<\/code>. {}<\/code> is filled with the file name at execution time.<\/p>\n\n\n\nThe Linux
ln<\/span><\/code> command<\/h4>\n\n\n\nln<\/code> command is part of the Linux file system commands.<\/p>\n\n\n\nHard links<\/h4>\n\n\n\n
ln <original> <link>\n<\/code><\/pre>\n\n\n\nln recipes.txt newrecipes.txt\n<\/code><\/pre>\n\n\n\n![\"Screen-Shot-2020-09-02-at-11.26.21\"\/](\"https:\/\/www.freecodecamp.org\/news\/content\/images\/2020\/10\/Screen-Shot-2020-09-02-at-11.26.21.png\")
<\/figure>\n\n\n\n![\"Screen-Shot-2020-09-02-at-11.26.07\"\/](\"https:\/\/www.freecodecamp.org\/news\/content\/images\/2020\/10\/Screen-Shot-2020-09-02-at-11.26.07.png\")
<\/figure>\n\n\n\nSoft links<\/h4>\n\n\n\n
-s<\/code> option of ln<\/code>:<\/p>\n\n\n\nln -s <original> <link>\n<\/code><\/pre>\n\n\n\nln -s recipes.txt newrecipes.txt\n<\/code><\/pre>\n\n\n\nl<\/code> flag when you list the file using ls -al<\/code>. The file name has a @<\/code> at the end, and it’s also colored differently if you have colors enabled:<\/p>\n\n\n\n![\"Screen-Shot-2020-09-02-at-11.27.18\"](\"https:\/\/www.freecodecamp.org\/news\/content\/images\/2020\/10\/Screen-Shot-2020-09-02-at-11.27.18.png\")
Now if you delete the original file, the links will be broken, and the shell will tell you “No such file or directory” if you try to access it:<\/p>\n\n\n\n![\"Screen-Shot-2020-09-02-at-11.27.03\"\/](\"https:\/\/www.freecodecamp.org\/news\/content\/images\/2020\/10\/Screen-Shot-2020-09-02-at-11.27.03.png\")
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gzip<\/code> <\/span>command<\/h4>\n\n\n\ngzip<\/code> command.<\/p>\n\n\n\ngzip filename\n<\/code><\/pre>\n\n\n\n.gz<\/code> extension to it. The original file is deleted.<\/p>\n\n\n\n-c<\/code> option and use output redirection to write the output to the filename.gz<\/code> file:<\/p>\n\n\n\ngzip -c filename > filename.gz\n<\/code><\/pre>\n\n\n\n