Linux File Types and File Permissions

greetings and salutations and thank you for clicking on the video today we're going to talk about Linux file types and Linux file permissions this video is for newcomers to Linux especially those of you who are coming from the world of Windows the way Linux handles files is very different than the way the Windows operating system handles its files and it can be quite confusing for people who are not used to working in a Linux environment this video probably will be quite tedious for those of you who are already well versed in the ways of Linux so keep that in mind I'm going to cover simple concepts we're going to take a deep dive into this I have covered these in past videos several times but usually in concert with a bunch of other concepts that I'm trying to present like how to use a terminal or talking about the Linux file system in general I'm going to omit a lot of that stuff today we're just going to talk about files so all we're going to talk about and how you can interact with them on your system and understand some of the strange error messages you might get when you're trying to do something with your computer so here are some basic concepts to keep in mind as we roll along let's first of all talk about Linux file types LS with the l option or long option tells you whether a file is a file or a directory that's if you're working in a terminal of course if you're working in a graphic user environment a file manager program those are usually represented quite simply by different icons in a graphic user environment directories are usually represented by a little picture of a manila folder and the reason why that is is because years ago in computer science class when they were explaining - as the difference between files and directories they used it a filing cabinet as an example and so therefore they said a file would represent something on a page a picture or text and then a directory is like a folder and you put a bunch of files that you want to direct grouped together in a folder and then you put all the folders in the files in the filing cabinet and the filing cabinet can hold files and folders the filing cabinet would represent a storage device like a hard drive so the word directory and the word folder are interchangeable but technically speaking when you're working at a terminal you would call it a directory and when you're working in a graphic user environment you would call it a folder but I will probably interchange those words as we go through the video simply because both words apply Linux does not need extensions to know what's in a file if you're used to working with Windows you're used to the concept of a file having a little three letter or four letter extension on the end that tells you what's in that file Linux doesn't need that a file can be called picture a file can be called song whatever and it will know the difference between a jpg and an mp3 and so when you're working with Linux especially when you're working in parts of the system that are not user friendly like working in the system directories you're going to see lots of files that don't have any extension and you're probably going to look at it and go well how do I know what it is we'll tell you how that works is the video roles on the file command will tell you what's in a file and I'll show you how to use that in a little while now let's talk about Linux file permissions because this is really the thing that makes people scratch their heads the file type thing yeah that causes a little bit of dismay but when they start working with the system all of these questions come up about file permissions and I get asked about this all the time which is the reason why I'm creating this video this way I can point folks to this video and then they'll learn everything they need to know so the first thing to understand about the Linux system is that everything about your computer is represented as a file files can contain all kinds of data I mean it can be text it can be pictures it could be sound it could be video whatever but a file can also represent something like your hard drive or your mouse or your keyboard or your display and that's how Linux works because it just looks at everything as being a file and all the Linux kernel does is move data back and forth from one file to another it's really that simple and the reason why Linux works that way is because that's how UNIX works Linux is an operating system that was designed to work alike Unix it's a work alike so that means that the UNIX system and the Linux system share a lot of the same file structures file permissions so if you're watching this video you ever get stuck in front of a straight UNIX machine you're not going to be lost it all works the same way UNIX is an old operating systems been around for a long time since the late 60s that's when they started developing it and UNIX is designed to run on mainframe computers big computers that used to fill up a whole room and those computers could have hundreds of users logged into them at any given time and each user would have an account on that system so you got to imagine that a lot of files are being created by a lot of different users and so therefore you have to have really strong permissions in place to keep everybody's data secure so every file or directory belongs to someone which means that every file that's created on the system it belongs to somebody whether it be the root user who is the administrator that's what we call the administrator in Linux and UNIX they can own a file or any of the users that have accounts on the computer can own a file every file or directory is assigned to a group a group is a way of taking a bunch of users and giving them all access to the same stuff now today with the modern Linux systems we use on laptops and desktops and you might only have two or three users or maybe you're the only user on the system groups don't make a whole lot of sense but modern Linux systems use groups to figure out what kind of access you have to certain parts of the system so if you are a Linux user and you're using something that's based on boom 2 or Linux Mint you're actually the member of a lot of groups already when you create a file it goes into your own personal group when your account is created they give you a group that is your user name so files that you create are pretty much automatically owned by you and they are assigned to your group files can be readable writable or executable or any combination of yes or no when it comes to those attributes a readable file means that you can actually get into it and see the contents you can display what's in the file a writable file means that you can modify that and it also means that you could delete a file so that gives you the ability to change and save your changes to a file or remove the file completely an executable file means that it can be run as a program you're telling the system that it has code in it that the Linux kernel can read and then it can actually do something with in for instance if you're writing scripts for bash then bash looks at that executable and says oh there must be code in here I can use and then it can run it directories have to be executable if you want to be able to get into them and create files or do anything with files within the directory a directory can be readable which means that you can see it's there but if it's not executable you can't actually get into that directory and do anything with those files so that's something to keep in mind the executable bit works differently with files and directories file permissions can be different for owners groups and the world you can have any combination so you can have a file that only you the owner can get into you can have a file that belongs to you but it's accessible by another group so you could have a whole group of users let's say that you had a project going and you were working on something and then everybody could be part of this one group and then you can create a file and then assign it to that group and as long as they have access to it in the group people work on it we don't use groups much these days so you know it's not something you really have to worry about too much but it's something to keep in mind and the last one is the world which means everybody all users anybody that has access to the system and that's one you really have to watch out for because if you have those set that means that anybody anywhere on the system who can navigate to wherever that file is can do something with it so if you have a file that you absolutely positively don't want anybody to look at or be able to change then you can turn off file permissions entirely for the world and then nobody will even know it's there and finally the root user or the administrator or the super user they have complete access to every file on the system if you are doing something with root user privileges you can destroy any data that's stored anywhere on the system and that includes very important critical system files so when you're doing things as root you need to proceed very cautiously because file permissions no longer apply now that we have the basics down let's get into actually putting this to work and let me show you how you can take advantage of this and understand how it's working we're going to be doing things in a terminal in this part of the video and the reason why is because I can show you exactly what's going on if you don't intend on using a terminal when you're working with your Linux system keep in mind that everything I show you can be done graphically as well and I'll show you how to do it graphically and in the latter part of the video so the first thing that we need to do is get some files to look at and I have created a directory called stuff and if we list the storage in there you see that I threw some files in here and it's all kinds of different files the kinds that you would come across on your system so we have some files that are pretty logical they have extensions that are created by programs and those extensions tell us what they are so we have a jpg we have a jiff we've got an mp3 we've done what we got a text file we've got a document file that's my French onion soup recipe there and then we got some files that don't have any extensions on them and we have color coding that kind of tells us what they are but we still don't know so if you want to know more about what you're looking at in a directory the best way to do that is to just list it with the L option and now we're going to get a lot of information about these files so the first part here might look like complete gobbledygook we're talking about right here but this is actually a bunch of important information right here and to figure out what's in there let's jump over here and look at this graphic so what we're looking at is the permissions bits on the file that actual information and the first thing that we have is a dash and if we come down here where the arrow points and look we see that that indicates a regular file just a dash means it's a regular file it's not a special file it's not a directory if you see addy there that means it's a directory if you see an L there that means it's a link now there are other file types but you are not going to come across them in your home folder it's just not going to happen they're going to be in the system so specialized file types that represent devices they have special different flags there that come up but like I said as an average user you're not going to see that very often then we have the permissions of the file and it's three groups of three right here so the first group of three represents the owner that's you all right you can read write and execute on this file so if you can read it it's got an R the W it means that you can write to it and execute means that you can execute the next group is for the next group of three represents the group and the next group of three the last one represents the world and remember this one's very important because anybody that can have access to your file in this case it's going to be able to read that file they're not going to be able to change it they're not going to be able to delete it but they are going to have access to its contents so that's how those permissions work so the next thing that you see on the list here is this number and this is you can just pretty much ignore this because all it is is links this is the links to the file the number of links which is not something that the average user really needs to worry about too much but it does show you so most files will have a link of one because there's only one file there but if you can have more links to a file you can have a file appear in other parts of the file system in that case you would see more links here we get the owner and the group these are the people that own the file and the group is it is assigned to and in this case most of the files in here are assigned to me since my user name is Joe and my group is Joe but we do have one that's assigned to somebody else this is Cindy's file right here this is the file size and it's it shows it in kilobytes 1024 K blocks actually and it it's a semi useless that way but there's a way to fix that if you're looking here just add an H to this listing and now we get humanly readable sizes on the text there so that's a little tip to keep in mind and then over here we've got the modification date if the file was modified modified more than a year's a year ago then we get the day and the year of its last modification so this Billy Joel Big Shot mp3 I've had it since 2009 and it has not been modified since then okay we have one here from 2004 and so on so we've got some pretty old files in here and it looks like I came up with my French onion soup recipe in 2010 if it's a file that's been created within the last year then it gives you the date and it'll give you the time that the file was created so that's the difference there and then finally here we get the file name now we can look at this and see that we have a bunch of regular files we have one link here this is a link to a picture called permissions and then it links to another file somewhere else in the system and it is called permissions diagram dot gif or gif or whatever you want to call that and so there you go but we've still having a hard time figuring out what some of these files are so we have a file that's called text but it might be called something else if it's called text we kind of know it's text so let's see what we got here we can use the file command and then put in text now the system will tell us down here at the bottom of the screen that this is an access key text file with line with no line terminators and what that's telling you is that the text in this file is just a big long string of words and spaces there are no carriage returns in that and that's because that file was probably created on a Windows System or it just doesn't have it so let's look at some other things here let's I mean we already know what it is because a lot of these files were created by programs that automatically put the extensions on there for the convenience of looking at what they are and also if you're going to share files with a Windows system it's nice to have an extension so they know what it is but let's just do it anyway so let's do file and we'll look at Billy Joel here there we go and it's telling us that this is an mp3 file and let's look at another one here let's look at our picture of beaker now there you go so that's how you can look at a file and go I don't quite know what that is let's see what it is let's try it on one more well now it says that this is a shell script okay if we look up here at the permissions for sync it that's an executable file which means that that's actually a program pretty cool huh let's clear the screen and see what else we can do here well I wanted to type ls' thank you all right now it makes sense so we have our files here so what can we do with them well let's talk first of all about changing file permissions as a user you have the ability to change file permissions on files that you own so if you want to tailor the file permissions for a particular file for whatever reason there's a couple of ways that you can do that you can do that from a GUI or a graphic user interface you can do that from a file manager or you can do it from a terminal I prefer to work with permissions at a terminal because you can use wildcards you can do a whole bunch of files or you can do one file you can do all kinds of things so I'm going to show you how to do that and I'm going to show you this command which is change mode and with no e so it's change mode with no lis or change mod however you want to say that but its mode that's what it's supposed to be and then there are a couple of ways to make this command work for us so let us try to make the file called txt executable and see what happens there's a symbolic way to pass information to the change mode command which involves using letters and pluses and minuses it's sort of like the attribute command or the attrib command in Windows if you ever played around with that if you remember that from the days of Dawson kind of the same sort of system I find it to be very confusing the only time that I ever used the symbolic method is to make a file executable because I'm going to make a file executable I just make it executable across the board so to do that I would use the plus sign and then we would say plus X and then when we give it our filename in this case we're going to do text and then we turn it loose lips we have an error and this is one that you're going to run into why can't I do that it says well the program is changed mod and it says changing from missions of the file called text and then it tells us that the operation is not permitted well why is the operation not permitted let's list that file again and see what's going on so we'll be well LSL we'll do text o at file a zone by sending I don't have permissions to work on that file looks to me since I am NOT in a group called Cindy and the file is owned by Cindy that the world permissions on this file will only allow me to read it so there's a couple of things that I can do here I could change the ownership of the file using a command called change own and I could make that file be any you know I could make it my file or I could give it to somebody else but what if I am a user on a system and I do not have administrator privileges but I got to do something with this file I need this information how am I going to get it well since I have read permissions that means I can copy the file so let's just copy it and we're going to put this file it's live copy text and we're going to put it into a file called Joe - text all right so should be able to get a copy of it okay let's just make sure it made it yep it's there so now what I should be able to do is do what we started to do and that's change the permissions and make this executable let's go back up here to our command and we'll just give it a different file name well that was successful so let's LS and we'll do a long listing again and we'll look for our file called Joe Tex there it is and you see that that is now executable so what if you do have privileges like that and you want to be able to give the file to another user so this is a concept where this is also how you would change what group a file is assigned to so let's look at that command real so let's just take the file txt and I'm going to change it to own owned by me so we would use sudo to get root privileges and act as the root user and then we would do change own and then we would tell it that I want this file to belong to me use a colon and then I would say I want this file to be in my group as well and then I'll give it a file name text so now when I issue this command it's going to ask me for administrator privileges and now that has been done so let's see there we go so now that file well we can't see that let's do LS l - L l thank you now we got it all right and you see now the file belongs to me it no longer belongs to Cindy and that's the basics of changing file permissions symbolically and changing the owners now I said that the symbolic method for changing file permissions I really have never gotten into it if you want to know more about how that works then what you can do is run man and then change mod here change mode and it will show you what it is how about typing that in correctly thank you what am I doing wrong oh I see there we go thank you and this will tell you all about how to use the that command this is how I use it this is the easiest way for me to do it we're going to look at the symbolic we talked about symbolic but we haven't showed you how to use it it confuses me I go crazy I use the octal method what does that mean so let's jump into that real quick go ahead and get to this different picture here the Linux permissions are stored in 8 well no they're stored in 3 bytes of data at the beginning of the file and a byte of data represents 8 bits when we use the octal method to represent data this would be like ASCII text or numbers or something like that we really only use 7 of those bits so the information about the permissions stored in those bytes is all numeric and we can use just real simple math to be able to represent those permissions so let's look here at user and you'll see that the read permission equals 4 and the write permission equals 2 and then the execute permission equals 1 so in this instance right here this particular file has all the permissions set to on so and all of the permissions added together equals 7 now I know in past videos I said it's a byte of data but we're only using 7 bits and I confuse some people and they thought that I was saying will abide is 7 bits no it's not we just used 7 or rather that a byte was 7 bits and not 8 bits and I've confused some people this is the correct way to do this it's yes it's 8 bits of data a byte is eight bits but we're only using 7 to represent what we're talking about here so just make sure that that's completely clear so nobody puts in the comments well the bytes a bit I know that okay so how do we use this in practice let's go back to our files here and I'll just do a regular LS and let's say that we wanted to change the permission of Joe text so the first thing that we want to do is take a look at what the permissions are set at so that would be LS L Li autofill and currently this file is set to execute I don't want this file to be executable let's say that I want this file to be readable and writeable I mean but nobody else can actually see the file so once again we do change mode and this time I'm going to put in numbers so if I want the file to be readable and writeable but not executable that equals 6 if I want the file for the group to be just readable that equals 4 if I want the file for everybody else on the computer to be completely inaccessible they can't read it they can't write it they don't do anything with it that would be 0 now we'll give it the name of the file to work with so let's LS dash L that file and now you see that we have those permissions set that way you may see this command done with 4 characters so let's do that one more time because sometimes in some documentation you'll see this let's go back over here we can put an O in front and just to show that it changed something we're going to make this file readable by everybody in the world so now we have zero 644 now I'm going to issue the command and we'll list it again now let's see it's readable to everyone well what's that first character for that zero there that's if you are going to assign a special file type to a file that's what that represents in this case we put a 0 in which means that hey we are going to just leave the file as a regular file we're not going to do anything special to it so in normal practice just doing the command this way works just fine but with three characters that's what I wanted to show you but to be absolutely technically perfect about it you'd put a character up front so if you see that that's what that comes from but in normal practice just doing three characters is just fine and you can and you can do that with a bunch of wild card files so let's do that with the text files on the system I'll show you how to do it with a wild card so we'll list the storage and this time around we're just going to look at everything that has the extension text on it so use the glob there and now we're listing just things that have the extension text and right now we only have one file that has that extension on it don't we but there was more in there so let's see here let's I guess we need to add text to the end of a file so let's do this let us move text to txt dot txt and now we're going to list those again now you see we get two file so if I want to change the permission on both those files how would I do that and well what you would do is come back up here and you will change this to dot or rather glava or asterisk or whatever you want to call that thing txt star txt now every file in the system that is txt that's the wrong command let's just type that in let's say we're going to make this one we'll just for fun make them executable but nobody else can get to them just so we see that they change okay so now what the system is going to do is it's going to apply this to those two files did it do it and we'll do and let's just do start our text again now you see that those permissions have all changed so that's how I do it when I'm working at a directory so that's it gang that's really all you need to know about changing file permissions that it's really that simple but the the rules are rigidly enforced and that's something that you have to keep in mind so as you're moving through working on the system like this you might find that you get those sort of errors those are permission errors and that's why you can't access stuff on the system that way now that we've gone through all that stuff in the terminal let's look at how you do it in the file manager in a Linux system and today we're looking at Linux Mint with Nemo Nemo is one of my favorite file managers it has a lot of really cool features in it and depending on what distribution you are running you may or may not have some of these features in Ubuntu the default file manager is called Nautilus doesn't have a lot of it's pretty stripped down doesn't have a lot of features if you are running the mates or matei desktop however you want to say that then you are going to have the kaha file manager that's pretty well featured if you're running for instance the XS EE desktop then your file manager will probably be thunar for KDE desktop you're going to be using dolphin and so on and so on but file managers or file managers or file managers and the basics remain the same so we're going to look at how we do all the stuff that we did in the terminal in the file manager well the first thing that you can see is that we can pretty much figure out what the file types are just by looking at the screen because linux has figured out what they are and it assigns an icon to things that might be an icon for a program that opens it in this case this is an audio file so we get a musical note and then this is a picture so obviously we have a picture there and and so forth and even this particular one which is actually a link we get to see the picture that it links to so you can dig deeper into file types simply by telling it that you want to make a list of the files instead of looking at icons and over here in this column it tells us exactly what we're looking at that's a folder that's an image this is audio this is text and it will even identify that sink it is an executable program so that is pretty cool file types pretty much well taken care of in the file manager and you don't have to worry about that sort of thing so how do we change file permissions on a file well let's see what file permissions did we leave on this we will do a right-click and then we will choose properties and then go to permissions and now we see all the permissions that we have set and the last time around I said that people could read and write it but nobody else had access to it not even people who are member of the group Joe so what if we want to change that no big deal just change that to read and write and then we'll just change this to none that way the world has none if we wanted to make it executable we would just click there and that's it we have changed the permissions on that file now the one thing that we can't change here is the owner because we don't have permission to do that I'm running as a standard user right now so if I wanted to change the owner then I would have to login I would actually have to run this program as a root user and I'll show you how to do that in just a second these are the groups that I belong to I can assign this file to any group that I belong to now these are system control groups right here you really don't want your files to be owned by system control groups in Ubuntu based Linux like Linux Mint but if I was a member of a group let's say called development project something crazy like that then I could say this file would be accessible by anybody who's a member of that group and this is where I would set that here what's the time you just leave that alone so if we wanted to change the owner of a file well the quickest and dirtiest and easiest way to do that is to copy the file to that owner so let's say that I wanted to jump over into let's let's open up let's do this here let's split-screen this and then over here in this one okay we'll just go over here like this let's go to filesystem and then we're going to jump into the home directory which is already highlighted then I can jump into Cindy's let's say that I wanted to grab a picture out of Cindy's stuff okay just anything will do let's get a picture of Carly the dog okay and if I wanted to make a copy of that obviously because I can see these files I have read access to them and if I can read it then I can copy it like this now I have a copy of that picture so if I look at the properties on the original file let us know I want to compress I want to look at the properties and we go to permissions you'll see that it's owned by Cindy and there you go so if I look at my copy that I just made we do the same thing here see this one is owned by me that's because I copied it over and when the system created the file in my home folder it used the default settings to create it with the permissions that it would have if I created the file myself but what if I really do need to change the ownership of a file let's say that I want somebody to be able to navigate to my home folder and grab a file or directory' full of stuff and drag it over to them they can actually come get it and there you go how would I do that well in this case I'm going to have to change the owner so let's just go ahead and look at my directory here and then I'm going to open this directory in a terminal and now what we need to do is get Nemo running as an administrator and we do that by doing sudo Nemo it's going to ask for a password make sure we can do this and now we get a different window and look we have a warning message up here that says we're running this as an administrator and it's opened up to my home folder here and so now we can change the ownership of a file so let's just go back into this picture of Carly and we'll do properties I go to permissions now you see that I can choose the owner here so let's do that and you'll see that there are actually a lot of users on your system this these are system users this isn't you know what you're looking at here is a bunch of system type users so you'll need to scroll to find Cindy here so now we're going to make this file Cindy's and we're going to put it in the group Cindy as well now instead of just seeing groups that we belong to look at this there are all of the groups on the system so if we want to put it in the user group that's fine and we're going to leave the permissions as they are read and write and read only for group and read for the world and then we will close now if we look at the properties again just to make sure here just kind of belaboring a point we see that that is Cindy's file guess what I'm not going to be able to delete that well I can in a I can do it here in the root Nautilus but let's get out of this we've made our changed so I want to prove something here that I'll go ahead and close that terminal yes now let me try and delete this file it let me delete it let's see if it put it in the trash yep it put it in the trash so it will let me delete the file restore deleted items let's see if I can I can open the file yes I can do that it's owned by Cindy let's see if I can permanently delete the file it will let me delete files I was thinking that it wouldn't so I just found out something myself because I figured that I couldn't delete a file I guess maybe it's because it's in my own home folder and it figures if it's in my home folder and I want to get rid of it I can do it but if I was doing that in a terminal and I was doing it in Cindy's home folder I couldn't do it like there's no way that I could delete a file in Cindy's let's just go to file system we go to home and we'll go to Cindy and we'll go to pictures and let's see we'll just try and delete this one new it's not going to let me do it nope I can't even activate that command because it's not in my home folder and I do not have the permissions to be able to delete files in my home folder so there you go that's how that works gang now here's another thing that I need to point out you can move files around on the system and if you do it as the Super User what's going to happen is is that you are going to create the copy of the file as the Super User which means that will have root permissions only so let's do this let's get into stuff again it's got to be a capital T alright so we'll just list the storage here and let's just make a copy of a file as root so I'm going to do sudo CP and we will copy Jo text and we'll just make this file too let's go ahead and do that but I'm doing it as the root user so now I give it my password I've made my copy do it LS with the long option and look this file is now owned by root this file - right here I shouldn't be able to remove this with normal privileges so let's go ahead and try that file - this is just a remove command see if it'll take it out of the system nope file is write protected and I'm not going to be able to do that but it is prompting me to go ahead and remove it that is because when you're fooling around with permissions and things like that it is quite possible for you to create a file with the wrong owner and the wrong permissions that you yourself can't delete Linux knows this so now it's going to go ahead and let me delete this file and that's because I'm doing it within my own file system if I try to do this in the root filesystem I may just get told no no you can't delete this file and the only way I'd be able to do that is to do it as the super user but since we're within our own home directory here the system kind of is helping us out it's going do you really want to do this and I'm going to tell it yes and then we'll just run that command again and now you see that file is gone so that's how file permissions work in Linux and UNIX and I certainly hope that this has helped to clear the air for some of you who have a hard time dealing with the concept of file permissions it's one of the features that makes Linux and UNIX very secure in a networked environment like being on the Internet and it's a big difference from other systems so pretty cool knowledge to have in your back pocket one final note about file permissions you might hear the concept of a you mask being tossed around in different forums the you mask is what your distribution uses to actually set a default file permission scheme for users and as a user you have acts to your you mask and you can have the system create files by default with whatever kind of permissions that you want so for instance if you are running in a situation where you need really high security and you do not want to share files with anybody else on the system you can set your you mask to create files that give the world absolutely no access at all there's an article about how to do this in a bun - and Linux Mint and it is right here actually this probably would refer more to a bun - I would suggest that if you wanted to change the you mask in Linux Mint that you look up how they different do it because they do it differently Ubuntu automatically creates files that have read and write permissions set on both the owner and the user or rather the owner in the group I'll get it straight sooner or later and Linux Mint by default sets its permissions to give the owner read and write access and the group only read access so it is a little bit different between the two distributions and each distribution of Linux may do it in a slightly different way exactly where they store the umask information so if you want to do it in a bun - I will go ahead and link this article in the description since I'm showing it but if you're doing it on another distribution then I would suggest doing a search for change you mask in Linux Mint change you mask in fedora change you mask in Arch Linux so that you make sure that you get it correct so thank you for watching the video I hope this helped and please be sure and check out easy Linux on the web check out easy Linux on facebook and check out freedom penguin comm for lots of cool stories about Linux the wallpaper that you saw in this video is available at the easy Linux site it is linked in the description to the video just go to the easy Linux site and then go to wallpapers and you can snag that for yourself people always ask about wallpapers so that's why I'm putting that in there thank you very much for watching we will do again soon

Channel: Joe Collins

Views: 55,787

Keywords: Linux, OS, Computer, Laptop, Desktop, Server, File Permissions

Id: SdgiYoOi0CY

Length: 46min 5sec (2765 seconds)

Published: Tue May 30 2017