# Must know basic Linux commands Linux is an open-source operating system with a huge number of distributions, some of them: * Ubuntu * Linux Mint * CentOS * Fedora * Debian Most of these operating systems have a graphical interface that provides a wealth of features, but the greatest power of Linux comes with the use of a command-line interface (CLI) For this reason, it is useful to know some of the most common Linux CLI commands. ## Commands for working with files ### `cd` command Many times, we can change the active directory we are currently working with. This is done with the `cd` command. ```bash cd /home/user/folder1 # Current directory will be /home/user/folder1 ``` ### `ls` command The `ls` command is used to display the contents of the current directory. ```bash ls # Output example Desktop Documents Downloads Music Public Temp .gitconfig ls -R # list all the files in the sub-directories ls -a # show hidden files ls -al # list all info's about a file (size, owner ...) ``` ### `pwd` command The command tells us which is the currently active directory. ```bash pwd # return the current directory # output example /home/user/folder1 ``` ### `cat` command Perhaps the most commonly used command in Linux, as it allows you to create, combine files. ```bash cat > file # create file with name file in current directory cat file1 file2 > file3 # joins file1 and file2 and create output file3 in current directory ``` ### `cp` command `cp` command disables copying a file from the current directory to another. ```bash cp document.txt /home/user/Documents # copy document.txt from current directory to folder called Documents ``` ### `mv` command `mv` allows you to move files. ```bash mv document.txt / home / username / Documents # move document.txt from current directory to folder called Documents ``` You can also rename files with this command. ```bash mv oldname.txt newname.txt # rename file from oldname.txt to newname.txt in the current directory ``` ### `mkdir` command This command creates new folders. ```bash mkdir Archive / Documents # create folder called Documents from current directory mkdir -p Archive / 2021 / Documents # create folder 2021 between folders Archive and Documents ``` ### `rmdir` and `rm` command Commands can be used to delete folders. With rmdir we can only delete **empty folders**. With rm, you can delete the entire folder (check before use because it is not possible to restore the deletion). ```bash rmdir NotusefulFolder # remove NotusefullFolder (it is empty) from the current directory rm Folders / NotInUse # remove all files and folders in folder NotInUse from the current directory rm -r NotUsefulFolder # command equal to rmdir ``` ### `touch` command The command allows you to create new files. ```bash touch file.txt # create a file in the current directory ``` ### `find` command Used to search for a specific file. ```bash find ``` ### `cat` command This command allows us to print the contents of a file. ```bash cat ``` ### `head` command Display us the first 10 lines of the file. ```bash head file.txt ``` ### `tree` command Return filesystem directory tree. ```bash tree ``` ## Setup commands ### `sudo` command Abbreviation for "SuperUser Do", with this command we can execute commands that require administrative authority. ```bash sudo # In the next step you must input the password for the root/admin user ``` ### `df` command Shows us disk usage in KB and percent. ```bash df # Return disk usage in KB df -m # Return disk usage in MB ``` ### `kill` command The Kill command allows you to stop a specific process. ```bash ps # return list of active processes kill 11111 #kill process with PID 11111 ``` ### `zip` and `unzip` commands They allow us to create compressed zip files and expand zip files. ```bash unzip zipped_file.zip # command unzip zipped_file.zip file ``` ## `ping` command The command is used in most cases when we want to check if a device is active on the network ```bash ping hashnode.com ``` ### `hostname` command The command tells us the name of the device ```bash hostname # return hostname of the device # example output server ``` ### `useradd` and `passwd` command `useradd` allows us to create a new user. Passwd allows us to change or set a password. ```bash useradd NewUserName # create new user userdel UserName # delete user passwd UserName # can set a password if doesn't exist or change if exists ``` ### `wget` command A very useful command to download files. ```bash wget DownloadFileURL # download file in current directory ``` ### `free` command After giving us the amount of memory used. ```bash free -h # return usage of memory - RAM (human-friendly numbers and units) ``` ### `shutdown` and `reboot` command Simple commands - the sessions already name what they learn. ```bash shutdown # shutdown computer reboot # reboot computer ``` Maybe if you have read in detail and gotten to know the Windows terminal, then you have noticed some commands are the same. Of course, there are even more of these commands, but I mentioned the most commonly used ones. If I forgot any, and you find it important to use in Linux, mention them in the comments 😊.