Docker Tutorial for Beginners [2021]

welcome to the ultimate docker course in this course i'm going to take you on a journey and teach you everything you need to know about docker from the basics to more advanced concepts so by the end of this course you'll be able to use it like a pro as part of your software development workflow if you're looking for a comprehensive and highly practical course that takes you from zero to hero this is the docker course for you we're gonna start off with a really simple project so you understand the basics then we'll use docker to run and deploy a full stack application with a front end back end and a database so you learn all the necessary techniques and apply them to your own projects i'm ash hamadani and i've taught millions of people how to advance their software engineering skills through my youtube channel and online onlineschoolcodewithmash.com if you're new here be sure to subscribe as we upload new videos all the time now let's jump in and get started let's quickly talk about what you need to know to take this course to take this course you don't need any prior knowledge of docker because i'm going to teach you everything from scratch but you should have at least three months of programming experience ideally you should have built at least one application so you should know concepts like front-end back-end api and database it doesn't matter what languages and frameworks or what database engines you're familiar with but you should know what these concepts are all about also you should be familiar with basic git commands like cloning a github repository committing code pushing and pulling just the basics nothing more with all that let's move on to the next lesson now we all have different ways of learning things but let me tell you what i think is the best way to take this course this course is highly practical so you should be active while watching this course in my opinion it's best if you watch each lesson take some notes you can either take notes on a piece of paper or using your favorite note-taking tool just write some keywords some keywords that help you remember what we talked about then after each lesson go through your notes and repeat the same steps i have taken in that lesson so if i talked about a bunch of commands play with those commands make sure you understand how they work if you follow that i promise you by the end of this course you're gonna master docker and use it like a pro alright our journey to master docker begins here in every section you're going to discover something new about docker in this section we're going to talk about what docker is and why it's so popular then we're going to talk about virtual machines and containers next we're going to talk about the architecture of docker so you understand how it works then we're going to install docker and get our hands dirty i'm going to give you an overview of your development workflow with docker and then we're going to see that in action using a really simple example so by the end of this section you will have an idea what docker is all about i'm so excited about this section i hope you are too so let's jump in and get started so what is docker and why is everyone using it these days well docker is a platform for building running and shipping applications in a consistent manner so if your application works on your development machine it can run and function the same way on other machines if you have been developing software for a while you've probably come across this situation where your application works on your development machine but doesn't somewhere else can you think of three reasons why this happens well this can happen if one or more files are not included as part of your deployment so your application is not completely deployed it's missing something this can also happen if the target machine is running a different version of some software that your application needs let's say your application needs node version 14 but the target machine is running node version 9. this can also happen if the configuration settings like environment variables are different across these machines and this is where docker comes to the rescue with docker we can easily package up our application with everything it needs and run it anywhere on any machine with docker so if your application needs a given version of node and mongodb all of these will be included in your applications package now you can take this package and run it on any machine that runs docker so if it works on your development machine it's definitely going to work on your test and production machines now there's more if someone joins your team they don't have to spend half a day or so setting up a new machine to run your application they don't have to install and configure all these dependencies they simply tell docker to bring up your application and docker itself will automatically download and run these dependencies inside an isolated environment called a container and this is the beauty of docker this isolated environment allows multiple applications use different versions of some software side by side so one application may use node version 14 another application may use node version 9. both these applications can run side by side on the same machine without messing with each other so this is how docker allows us to consistently run an application on different machines now there is one more benefit here when we're done with this application and don't want to work on it anymore we can remove the application and all its dependencies in one go without docker as we work on different projects our development machine gets cluttered with so many libraries and tools that are used by different applications and then after a while we don't know if we can remove one or more of these tools because we're always afraid that we would mess up with some application with docker we don't have to worry about this because each application runs with its dependencies inside an isolated environment we can safely remove an application with all its dependencies to clean up our machine isn't that great so in a nutshell docker helps us consistently build run and ship our applications and that's why a lot of employers are looking for people with darker skills these days so if you're pursuing a job as a software or devops engineer i highly encourage you to learn docker and learn it well and that's exactly what this course is all about i'm going to take you on a journey and teach you everything you need to know about docker so you can use it like a pro no copy pasting commands here so in the last lesson i briefly talked about containers a container is an isolated environment for running an application now one of the questions that often comes up is how are containers different from virtual machines or vms do you know the differences well a virtual machine as the name implies is an abstraction of a machine or physical hardware so we can run several virtual machines on a real physical machine for example we can have a mac and on this mac we can run two virtual machines one running windows the other running linux how do we do that using a tool called hypervisor i know it's one of those computer science names in simple terms a hypervisor is software we use to create and manage virtual machines there are many hypervisors available out there like virtualbox and vmware which are cross-platform so they can run on windows mac os and linux and hyper-v which is only for windows so with a hypervisor we can manage virtual machines now what is the benefit of building virtual machines well for us software developers we can run an application in isolation inside a virtual machine so on the same physical machine we can have two different virtual machines each running a completely different application and each application has the exact dependencies it needs so application 1 may use node version 14 and mongodb version 4 while application 2 may use node version 9 and mongodb version 3. all these are running on the same machine but in different isolated environments that's one of the benefits of virtual machines but there are a number of problems with this model each virtual machine needs a full copy of an operating system that needs to be licensed patched and monitored and that's why these virtual machines are slow to start because the entire operating system has to be loaded just like starting your computer another problem is that these virtual machines are resource intensive because each virtual machine takes a slice of the actual physical hardware resources like cpu memory and disk space so if you have 8 gigabytes of memory that memory has to be divided between different virtual machines of course we can decide how much memory to allocate to each virtual machine but at the end of the day we have a limit in terms of the number of vms we can run on a machine usually a handful otherwise we're going to run out of hardware resources now let's talk about containers containers give us the same kind of isolation so we can run multiple applications in isolation but they're more lightweight they don't need a full operating system in fact all containers on a single machine share the operating system of the host so that means we need to license patch and monitor a single operating system also because the operating system has already started on the host a container can start up pretty quickly usually in a second sometimes less and also these containers don't need a slice of the hardware resources on the host so we don't need to give them a specific number of cpu cores or a slice of memory or disk space so on a single host we can run tens or even hundreds of containers side by side so these are the differences between containers and virtual machines let's talk about the architecture of docker so you understand how it works docker uses a client server architecture so it has a client component that talks to a server component using a restful api the server also called the docker engine sits on the background and takes care of building and running docker containers but technically a container is just a process like other processes running on your computer but it's a special kind of process which we're going to talk about soon now as i told you unlike virtual machines containers don't contain a full-blown operating system instead all containers on a host share the operating system of the host now more accurately all these containers share the kernel of the host what's a kernel a kernel is the core of an operating system it's like the engine of a car it's the part that manages all applications as well as hardware resources like memory and cpu every operating system has its own kernel or engine and these kernels have different apis that's why we cannot run a windows application on linux because under the hood this application needs to talk to the kernel of the underlying operating system okay so that means on a linux machine we can only run linux containers because these containers need linux on a windows machine however we can run both windows and linux containers because windows 10 is now shipped with a custom built linux kernel this is in addition to the windows kernel that's always been in windows it's not a replacement so with this linux kernel now we can run linux applications natively on windows so on windows we can run both linux and windows containers our windows containers share the windows kernel and our linux containers share the linux kernel okay now what about mac os well mac os has its own kernel which is different from linux and windows kernels and this kernel does not have native support for continuous applications so docker on mac uses a lightweight linux virtual machine to run linux containers all right enough about architecture next we're going to install docker and that's where the fun begins all right now let's install the latest version of docker if you have an existing version of docker on your machine i highly encourage you to upgrade to the latest version because your version might be old and not compatible with the version i'm using in this course so here i'm using docker version 20.10.5 okay so to get docker go to this page docs.docker.com get docker or you can just google get docker or install docker now on this page you can see instructions for downloading and installing docker desktop for mac and windows as well as docker engine for linux so on mac and windows we have docker desktop which is the combination of docker engine plus a bunch of other tools at the time of recording this we don't have docker desktop for linux we only have the docker engine but of course that might change in the future so a couple of notes for my mac and windows users let's go to this page so over here you can download the latest version from docker hub but before doing this i highly encourage you to go through a system requirement and make sure your computer satisfies these requirements otherwise you might encounter weird issues so the installation is pretty straightforward when you go to this page you're going to download a dmg file just drag and drop this onto the applications folder and then start it this is very important a lot of people miss that step so when you start docker engine by double clicking on this application you're going to see the docker icon on the top status bar if you don't see this docker engine is not running and there is nothing you can do so you have to wait for this to start the same applies to my windows users so back to this page let's look at the instructions for windows so once again you can download the latest version from docker hub but once again make sure to read system requirements one of the things that is really important is enabling hyper-v and containers windows features so i don't have a windows machine to show you here but just go to the page where you can turn on or turn off windows features there make sure you have enabled hyper-v and containers it's pretty straightforward but if you can't find it just google it i'm pretty sure there are tons of articles out there also at the end of the installation you might get an error saying ws2 installation is incomplete basically what this error is saying is that you need to upgrade the linux kernel that is shipped with your windows so just click on this link this is going to take you to this page on microsoft.com where you can download the latest linux kernel so just click on this link to get an msi file run it and then you have to restart your computer now once your computer is restarted you need to wait a little while until docker engine started depending on your machine this might take several seconds or up to a minute so wait a little while then open up a terminal window and run docker version so over here you can see the version of the client and the server if the server which is docker engine is not running you are not going to see this information and this applies to all operating systems windows mac os and linux so make sure docker engine is running before going forward if you encounter any errors you can post your question on our forum at forum.codewithmosh.com or if you want a faster response just google the error message i'm pretty sure hundreds of people have encountered the same problem as you now let's talk about your development workflow when using docker so to start off we take an application it doesn't matter what kind of application it is or how it's built we take that application and dockerize it which means we make a small change so that it can be run by docker how we just add a docker file to it a docker file is a plain text file that includes instructions that docker uses to package up this application into an image this image contains everything our application needs to run everything typically a cut down operating system a runtime environment like node or python it also contains application files third-party libraries environment variables and so on so we create a docker file and give it to docker for packaging our application into an image once we have an image we tell docker to start a container using that image so a container as i told you is just a process but it's a special kind of process because it has its own file system which is provided by the image so our application gets loaded inside a container or a process and this is how we run our application locally on our development machine so instead of directly launching the application and running it inside a typical process we tell docker to run it inside a container an isolated environment now here's the beauty of docker once we have this image we can push it to a docker registry like docker hop docker hub to docker is like github to git it's a storage for docker images that anyone can use so once our application image is on docker hub then we can put it on any machines running docker this machine has the same image we have on our development machine which contains a specific version of our application with everything it needs so we can start our application the same way we started it on our development machine we just tell docker to start a container using this image so with docker we no longer need to maintain long complex release documents that have to be precisely followed all the instructions for building an image of an application are written in a docker file with that we can package up our application into an image and run it virtually anywhere this is the beauty of docker next we're going to see this workflow in action in this design i'm going to walk you through a typical development workflow now don't try to memorize anything in this lesson because i just want you to see the big picture so everything i show you in this lesson we're going to cover in depth later in the course so here in this terminal window i'm currently on my desktop i'm going to create a new directory called hello docker then go inside this directory and open it in visual studio code so i'm going to use vs code as my editor but you can use any editor that you prefer okay now in this directory i'm going to add a new file called app.js you're going to write one line of javascript code you don't have to be a javascript developer you don't even need to learn javascript so just follow along with me so here we're going to write console in lowercase dot log hello so with this we're going to print a message on the terminal let's say this is an application and we want to dockerize this application so we want to build run and ship it using docker so typically without docker if you want to ship this application or more accurately this program to a different computer on that computer we need to install node and then we can go to the terminal and type node app.js so we get the output so here are the instructions for deploying this program we need to start with an operating system then we need to install node which is an execution environment for javascript code next we need to copy our application files and finally we need to run node app.js so we have to follow four steps just for a simple program what if you were working with a really complex application you would end up with a complex release document that had to be precisely followed now this is where docker comes to the rescue we can write these instructions inside a docker file and let docker package up our application so back to vs code we're going to add another file to this project called docker file so capital d and all the other letters are lowercase and this file doesn't have any extensions okay now vs code is asking if you want to install the recommended extensions for docker we can go ahead with that good so back to this docker file here we write instructions for packaging our application so typically we start from a base image this base image has a bunch of files we're going to take those files and add additional files to it this is kind of like inheritance in programming okay so what is the base image well we can start from a linux image and then install node on top of it or we can start from a node image this image is already built on top of linux now how do i know these names well these images are officially published on docker hub so if you go to hub.docker.com and search for node you can see the official node image here so docker hub is a registry for docker images now back to our docker file so we start from a node image now if you look at docker hop you will see that there are multiple node images these node images are built on top of different distributions of linux so linux has different distributions or different flavors used for different purposes now here we can specify a tag using a column to specify which linux distribution we want to use for this demo i'm going to use alpine which is a very small linux distribution so the size of the image that we're going to download and build on top of is going to be very small okay so we start from that image then we need to copy our application or program files for that we use the copy instruction or copy command we're going to copy all the files in the current directory into the app directory into that image so that image has a file system and in that file system we're going to create a directory called app okay now finally we're going to use the command instruction to execute a command what command should we execute here node app.js but this file is inside the app directory so we have to prefix it with the directory name alternatively here we could set the current working directory work dir to slash app and then we don't need to prefix this with the directory name so when we use this instruction all the following instructions assume that we're currently inside the app directory okay so these instructions clearly document our deployment process now we go to the terminal and tell docker to package up our application so we say docker build we need to give our image a tag a tag to identify so t here we specify a name like hello docker and then we need to specify where docker can find a docker file so we're currently inside hello docker directory and our docker file is right here so we use a period to reference the current directory let's go with that now you might be expecting an image file inside the current directory but back in vs code look there is nothing here because the image is not stored here and in fact an image is not a single file how docker stores this image is very complex and we don't have to worry about it so back to the terminal to see all the images on this computer we type docker images or docker image ls which is short for list so take a look on this machine we have a repository called hello docker in this repository we have an image with this tag latest so docker added this by default we'll talk about this later in the course but basically we use these tags for versioning our images so each image can contain a different version of our application okay now each image also has a unique identifier here we can see when the image was created and the size of this image so because we used node from linux alpine we ended up with 112 megabytes of data in this image so this image contains alpine linux node and our application files and the total size is 112 megabytes now if we used a different node image that was based on a different distribution of linux we would end up with a larger image and then when deploying that image we would have to transfer that image from one computer to another so that's why we use node alpine because this is a very small image okay so we have built this image now we can run this image on any computer running docker so on this machine which is my development machine i can say docker run and then type the image name hello docker and it doesn't matter which directory i'm in because this image contains all the files for running our application now look we see the message on the terminal now i can go ahead and publish this image to docker hub so anyone can use this image then i can go on another machine like a test or a production machine and pull and run this image in fact i've done this before recording this video so back to docker hub look i have this repository code with mosh slash hello docker now we can take this image and run it on any computers let me show you something really cool so let's search for play with docker let's go to this page and log in here we need to sign in with our docker id anyone can create this id on docker.com so let's go ahead and start a lab over here we can start a new virtual machine so let's add a new instance now this virtual machine is a black machine it only has an operating system which is linux and docker so in this terminal window if we type node look node command not found so node is not installed here but because we have docker we can pull and run the image that i published on docker hub so let me maximize this window by pressing alt and enter first let's run docker version so on this machine we're running docker version 20.10.0 so to pull and run my program first we type docker pool code with mosh slash hello dash docker alright docker downloaded this image we can verify it by typing docker what command should be run here docker images or image ls so on this machine we have this repository code with mosh slash hello docker and this repository contains a single image with this tag latest so now we can run this application exactly the same way we run it on my development machine so from any directory we can type docker run code with mosh slash hello dash docker and here's the message beautiful of course i had to cut this down in editing it took a little while to start this application on this very slow virtual machine but you got the point so we can take any application and dockerize it by adding a docker file to it this docker file contains instructions for packaging an application into an image once we have an image we can run it virtually anywhere on any machine with docker hey guys mosh here if you're serious about learning docker i actually have a complete docker course on my coding school codewithmosh.com this tutorial you've been watching is a cut down version of the complete course in the full course you will learn how to run and deploy a full stack application with a front-end back-end and a database our application also includes automated tests so it's a great real-world scenario for learning docker just like my other courses you will also receive a 30-day money-back guarantee and a certificate of completion you can add your resume in case you're interested you can find the link down below in the description box all right the next step in our journey is the linux command line but why linux what if you're a windows user well you still need to know a bit of linux for a number of reasons for starters docker has its foundations built on top of basic linux concepts so if you want to be productive and troubleshoot issues easily you need to know some of the basic linux commands also most tutorials online are based on linux commands so if you don't understand these basic commands you're not going to get far in my opinion learning linux is like learning english i think everybody should know some english these days you don't need to speak it or write a book in it but you need to understand it so unless you're a power linux user do not skip this section it's gonna be super easy and extremely useful so let's jump in and get started let's start up this section by talking about linux distributions also called linux distros so as you probably know linux is open source software and for this reason many individuals and communities have created their own version of linux called linux distributions each of these distributions is made to fit specialized needs like running servers desktop computers mobile phones and so on so we have ubuntu which is one of the most popular linux distributions we also have debian alpine which we briefly talked about it's a very small linux distribution we also have fedora centos and so on believe it or not there are more than a thousand linux distributions out there now most of these distributions support pretty much the same set of commands but sometimes you might discover differences along the way so be aware of that in this section we're going to use ubuntu linux because it's one of the most popular distributions but if you have a preference for another distribution that's totally fine all right let's see how we can run ubuntu on this machine from this lesson i want you to start taking notes so watch this video take some notes and then after the video repeat the steps i have shown you okay so we go to hub.docker.com and search for ubuntu over here you can see the official ubuntu image that's been downloaded more than 10 million times let's have a quick look here so for each image you can see the command to pull that image onto your machine now in this lesson i'm not going to use the pull command i'm going to show you a shortcut so here in the terminal instead of running docker pool ubuntu i'm going to run docker run ubuntu now if we have this image locally docker is going to start a container with this image otherwise it's going to pull this image behind the scene and then start a container so take a look see docker is unable to find this image locally and now it's pulling it from docker hub now what happened well docker started a container but because we didn't interact with this container the container stopped let me prove this to you so if you run docker ps we can see the list of running processes or running containers look we don't have any containers running here but if we type docker ps dash a for all we can see the stopped containers as well let me increase the size of this window so you can see it clearly good so we have two stopped containers the first one is using the ubuntu image this is the one that we just started and the second one is hello docker which we started earlier in the course so to start a container and interact with it we have to type docker run dash i t that is short for interactive we're going to start a container in the interactive mode and in this container we're going to load the ubuntu image which we have locally good now what we have here is called the shell a shell is a program that takes our commands and passes them to the operating system for execution okay now what we have here is called the shell prompt let me break it down for you so it doesn't look mysterious the first part root represents the currently logged in user so by default i'm logged in as the root user which has the highest privileges then after the add sign we have the name of the machine so this container has this id which is automatically generated by docker and in this case it's like the name of a machine okay and after the colon you can see forward slash that represents where we are in the file system a forward slash represents the root directory that is the highest directory in the file system we'll talk about that soon then we have a pound and this means i have the highest privileges because i've logged in as the root user if i logged in as a normal user instead of a pound we would see a dollar sign okay so in this shell we can execute a bunch of commands for example we can say echo hello and this prints hello on the terminal we can also say who am i this shows the current user so these commands that we're running here this shell program that i told you about takes these commands and passes them to the kernel for execution now let me show you something really cool if we type echo dollar sign 0 we can see the location of this shell program take a look so that is forward slash bin slash bash so bin is a folder or a directory and inside this directory we have a program called bash which is short for born again shell so apparently steve bourne is the first person who created a shell program bash or born again shell is a reference to steve bourne so bash is an enhanced version of the original shell program okay now one thing you probably notice is that in linux we use a forward slash to separate files and directories but in windows we use a backslash so that's one of the first differences the other difference is that linux is a case sensitive operating system so if you type echo with a capital e it's not going to work bash tells us echo command not found so lowercase and uppercase letters are different and this is not limited to commands it's applicable everywhere if you want to reference a file or a directory or a user pretty much anything we should always spell it properly with the right uppercase and lowercase letters now one last thing for this lesson using the up and down arrows we can go through the commands we have executed so far so this is a pretty useful shortcut you need to know because you don't want to type these commands manually all the time okay also using the history command we can see all the commands we have executed lately so take a look so earlier we used who am i we also used echo and so on now we can replay any of this command by typing an exclamation mark followed by the command number so if i type 2 this is exactly like running who am i now it's your turn i want you to pause the video go through your note and execute the commands i have shown you in this video these days most operating systems and development platforms come with a package manager you've probably worked with tools like npm yarn pip and so on here in ubuntu we also have a package manager called apt which is short for advanced package tool so let's execute this command look this command has a bunch of sub-commands so using list we can see the list of packages we can also search for them we can show details about the package we can install reinstall and remove a package and so on now technically apt is the newer package manager we also have apt-get which you see a lot in online tutorials going forward we're going to use apt because it's easier to work with so let's say we want to install a package called nano nano is a basic text editor for linux now if you press enter here we get an error because this image this ubuntu image we are running does not have nano so this is where we use apt to install this package so if we type apt install nano we get an error saying unable to locate package nano why is this happening well here in linux we have a package database and this database might contain hundreds of packages but not all these packages are installed so if you want to see all the packages in this database we type apt list look these are all the packages now in front of these packages you can see some of them are installed but not all packages in this database are installed when we type app install nano this command looks at the package database and in this database it cannot find a package called nano so this is where we use the update command to update the package database now let me press enter then x is going to all these sources like security.ubuntu.com and all these other websites to download the list of packages so now our package database is updated so if we run apt list we see far more packages and as you can see most of these packages are not installed because we don't have installed in front of them so now we can run apt install nano and nano is installed so here's what you need to take away before installing a package you should always run apt update to update your package database and then you can install a package like nano now we'll talk about nano later in this section but before going forward let's make sure that this package is installed properly so if you type nano great so here we have a text editor we can type something let me resize the window so down below you can see the shortcuts to exit we have to press ctrl and x now it's asking if you want to save the changes no so we're going to press n good we're back here we can clear the terminal window by pressing control and l okay so we have installed nano now let's say we want to remove it so we type apt remove nano it's asking for confirmation let's go ahead great so nano is gone if i type nano we get this error saying no such file or directory now here's a little exercise for you in this image we don't have python so we get an arrow so i want you to use apt to install python in this image make sure it works and then remove it so in linux just like windows our files and directories are organized in a tree in a hierarchical structure so in windows we have a structure like this with c drive on top of the hierarchy then below that we have directories like program files windows and so on in linux we have the root directory on top of the hierarchy below that we have a bunch of standard directories for example we have bin which includes binaries or programs we have boot which includes all the files related to booting then we have dev the first time i saw this i thought this is short for development it's not it's short for devices so in linux everything is a file including devices directories network sockets pipes and so on so the files that are needed to access devices are stored in this directory then we have etsy there are different opinions what is this short for but one common opinion is this is short for editable text configuration so this is where we have configuration files we also have home this is where home directories for users are stored so on a machine with multiple users each user is going to have a home directory here we also have root which is the home directory of the root user only the root user can access this directory then we have lib which is used for keeping library files like software library dependencies we have var which is short for variable and this is where we have files that are updated frequently like log files application data and so on and finally we have proc which includes files that represent running processes so once again in linux everything is a file processes devices even directories are files now you don't need to memorize any of these directories i just listed them here so as we go through the course these directories look familiar to you that's all next i'm going to show you how to navigate the file system and there you will see these directories one more time let's see how we can navigate the linux file system so the first command we're going to talk about is pwd which is short for print working directory with this we can see where we are in the file system so a forward slash represents the root directory now to see the files and directories here we type ls which is short for list so we have bin which we talked about earlier that is short for binaries this is where we have binary files and programs we have dev which includes files for devices we have boot which includes boot files etsy which includes configuration files and so on now by default ls lists these items on multiple lines if you don't like this layout and want to show one item per line you need to pass an option that is dash one you might prefer this layout we have another option dash l for seeing a long listing this listing includes more details so in the first column we have the permissions of this file or directory the first time you see this it might look really scary but trust me it's easier than you think we'll talk about that later in this section over here you can see the user that owns this file or directory we can see the size we can see the date and so on now to change the current directory we use the cd command we have the same command in windows now here we can type a relative or an absolute path a relative path is relative to where we are so in this root directory we have directories like bin boot and so on so this is a relative path now in contrast an absolute path always starts from the root directory so let's go to a directory starting with e now we can press tab to get auto completion beautiful now let's go to a directory starting with a now if you press tab nothing happens because we have multiple directories starting with a so we have to press tab one more time great so we have three entries three directories add user.conf alternatives and apt so let's type the second letter p and then press tab beautiful now let's see what we have in this directory so these blue items are directories and sources.less is a file now to get out of this directory we can go one level up by typing two periods again i'm pretty sure you're familiar with this but i want to cover it to make this section comprehensive so we can go one level up to get to the etsy directory or two levels up to get to the root directory look we're currently in the root directory now when using ls we can optionally specify a path let's say i'm somewhere in the file system but i want to look at the content of another directory i don't want to navigate to that directory so i'm currently in the root directory i want to know what files and directories we have inside the bin directory so once again we can type a relative path or an absolute path starting from the root directory so here are the binaries in this directory look at pwd that's the command that we just executed so pwd is a program in this directory here's another example look at echo so most of the commands we have been exploring so far are programs or binaries in the bin directory okay now let me show you a shortcut earlier i told you that here we have this home directory where each user has a home directory but the root user has a special home directory called root now to get here there are two options we can type an absolute or relative path and go to root but there is a shortcut so let me get out of this directory so i'm currently in the root directory to get to my home directory i can type a tilde and this applies to all users not just the root user whenever we type cd tilde we go to our home directory now right now there is nothing here but in the next lesson i will show you how to create some files in this directory so before moving on to the next lesson i want you to spend a couple of minutes and play with the commands we explored in this lesson navigate the file system get adventurous see what you can discover i'll see you in the next lesson let's see how we can manipulate files and directories so i'm currently in the root directory and i want to go to my home directory how can i do that do you remember we type cd tilde great now in this directory i want to create a directory called test so we type mkdir test let's verify it's right here as i told you before blue represents a directory now let's say we want to rename this directory how do we do that we use the move command with this we can rename files and folders or move them somewhere else so we can move or rename test to docker all right beautiful now let's go in this directory to create a new file we use the touch command so we can create hello.txt look we have this new file here this is a new empty file in the next lesson i will show you how to edit files so for now don't worry about it also using the touch command we can create multiple files in one go so we can create file 1 file 2 and file 3. now take a look beautiful now i've got a question for you how do we list these files with a single file per line do you remember we type ls dash 1. now let's say we want to rename hello.txt to something else once again we can use the move command so we type h press tab to get auto completion we can rename this to hello docker.txt or we can move it to a different directory for example we can move it to the etsy directory and here i'm using an absolute path because my path has started from the root directory now in this lesson i don't want to move this anywhere so i just want to rename this to hello docker.txt and if you're wondering how i remove this entire word in one go i press ctrl and w so let's bring it back hello docker.txt take a look good now let's see how we can remove one or more files to do that use the rm command like here we can type one or more files so we can say file1.txt file2.txt or we can use a pattern for example i can say i want to remove all files that start with file let's verify it beautiful we only have hello docker now let's get out of this directory and remove the directory itself so we type rm docker now we get an error saying docker is a directory so to remove directories we have to use the r option which is short for recursive so we want to remove this directory and all its content recursively now we press d tab beautiful so let's verify there is nothing here so let's quickly recap we use mkdir to create a new directory we use touch to create a new file we use move to move or rename files or directories and we use rm to remove files and directories now as an exercise go to your home directory create a bunch of files and directories rename them and then remove them in the next lesson i'm going to show you how to view and edit files all right let's see how we can edit and view files so earlier we briefly talked about nano now it's a basic text editor for linux now on this image that we are running we don't have nano so we have to install it do you remember the command for installing nano that is apt install nano all right now we have nano so we can launch it and optionally supply a file name let's say file1.txt so here we have a basic text editor we can type whatever we want and when we're done look down below the shortcut for exiting is control and x so i'm going to press that now it's asking if you want to save the changes so we press yes and here we confirm the file name we can keep the same file or change the file name let's go ahead so now in this directory we have file on the txt beautiful now to see the content of this file we have a few different commands the simplest one is cat and this has nothing to do with cats it's short for concatenate so later i will show you how we can use this command to concatenate or combine multiple files but with cat we can also see the content of a file so if we say cat file1.txt we can see the content of this file now cat is useful if our file is short and fits on one page but if you're dealing with a long file it's better to use the more command let me give you an example so i'm going to use cat to show the content of this file slash etsy slash add user.conf this is a really long file so if i scroll up look we have a lot of text now sometimes you don't want to see all the content in one go you want to scroll down you want to go page by page this is where we use the more command so more etsy slash adduser.conf now down below look you can see more 15 percent so we're seeing 15 percent of this file now if we press space we can go to the next page so now we're at the position 33 alternatively we can press enter to go one line at a time now the problem with more is that we can only scroll down we cannot scroll up so to do that we have to use a different command called less so to exit here we press q good now in this image we don't have less so once again we have to manually install it so apt install less so less is a newer command that is supposed to replace more let's go ahead great so let's look at the same file using the less command hcl slash adduser.com so now using the up and down arrows we can scroll down or up so just by pressing up and down arrows we also have space we can go to the next page and enter just like the more command and when we are done we can press q now we have a couple more commands for viewing the content of a file we have head which we can use to display the first few lines so here we can supply an option and say the number of lines we want to see is 5. let's look at the same file so this shows the first five lines of this file similarly we have tail which shows the last few lines so let's apply an option and say we want to look at the last five files that's it so to recap we can use nano to write something to a file we can use cat to view the content of small files less to view the content of long files in an interactive way and head and tail to view the first view or the last few lines of a file one of the important concepts in linux is the concept of standard input and output so standard input represents the keyboard and standard output represents the screen but we can always change the source of the input or the output this is called redirection let me show you using a few examples so we talked about the cat command to see the content of a file let's say file1.txt when we execute this command this command or this program reads data from this file and prints it on the standard output which is the screen that is why we see the content here but using the redirection operator which is the greater than sign we can redirect the output from the screen to let's say a different file so now cat will read the content from this file and write it to this file take a look so we have file to.txt if we view it we see the exact same content as file one okay now what is the point of this well earlier i told you that we can use the cat command to concatenate or combine multiple files so here we can say cat file1.txt and file2.txt if you press enter cat is going to read the data from both these files and print it on the terminal which is the standard output but once again using the redirection operator we can write the result to a different file combined the txt so this is how we can use this command to combine multiple files now the redirectional operator is not limited to the cad command we can use it pretty much anywhere for example earlier we talked about the echo command if we say echo hello we see the result on the terminal but if we say echo hello to hello.txt now we have a new file here hello.txt which contains hello so if you want to write a single line to a file we don't have to use nano we can use the echo command so echo whatever to whatever file the txt okay now here's a little exercise for you i want you to get a long listing of the files in the etsy directory and write the output to a file so pause the video and work on this for a few seconds so here's the solution to get a long listing we type ls-l then we specify the path the exit directory now instead of printing the result on the terminal we're going to write it to a file called files.txt okay now let's view this file perfect now one more thing before we finish this lesson using the greater than sign we can redirect the standard output but we also have the less than sign to redirect the standard input i personally haven't found many use cases for this so i didn't cover it in this lesson all right that's all about redirection next we're going to talk about searching for text and files hey guys mosh here if you're serious about learning docker i actually have a complete docker course on my coding school codewithmosh.com this tutorial you've been watching is a cut down version of the complete course in the full course you will learn how to run and deploy a full stack application with a front-end back-end and a database our application also includes automated tests so it's a great real-world scenario for learning docker just like my other courses you will also receive a 30 day money back guarantee and a certificate of completion you can add your resume in case you are interested you can find the link down below in the description box

Channel: Programming with Mosh

Views: 596,505

Keywords: docker tutorial, docker, learn docker, docker tutorial for beginners, what is docker, docker for beginners, devops tools, devops, web development, programming with mosh, code with mosh, mosh hamedani, introduction to docker, docker course, docker crash course

Id: pTFZFxd4hOI

Length: 56min 3sec (3363 seconds)

Published: Tue Mar 30 2021