File and Directory Operations Part 1
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>> Hey Cybrarians.
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>> Welcome back to the Linux+ course here at Cybrary.
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>> I'm your instructor Rob Goelz.
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In today's lesson,
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we're going to start with the first part of
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our two-part series on file and directory operations.
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Upon completion of today's lesson,
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you're going to be able to understand the importance
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of these operations that we do on text
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and files and directories and we're going to operate
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on files and directories using the command ls,
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make directory, move and copy.
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Let's go ahead and get to it with some demo time.
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Here we are back in our CentOS environment
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and we're going to cover the list command first day.
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I know we've used the list command already,
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but it is important, so we're going to
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expand upon it a bit in this lesson.
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The ls or list command is
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just used to list the contents of a directory,
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for instance, we're in my home directory.
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Let's do an ls and we can see
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all the files and directories
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that live in this directory.
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To get more information about any of these files,
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we can add the - L option,
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which gives us the long listing.
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This gives us all of the information about all of
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the files that are in here, displays the permissions.
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We see the permissions right here.
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We see the ownership.
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The user and group owner is me.
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We can also see the file size as
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well as the timestamp and the file or directory name.
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But notice when we're looking at these file sizes,
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they're hard to read.
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This whole column is just a bunch of numbers.
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Well, what do they mean?
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Well, we can fix this by adding the - H options.
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We'll do an ls-l for long listing,
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H in this directory.
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Now we can see that the files
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actually have appropriate sizes.
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Instead of this being 4096,
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we see that as 4k in size.
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Now, you probably didn't notice,
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but if you look here,
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what don't we see?
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What are some very important files
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that we covered previously that we don't see in here?
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Well, we don't see the bash files.
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We don't see any of those.
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How do we see the files like bash RC and bash history?
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We fix this by adding the a option for all.
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Now what this will display is any hidden files.
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Hidden files in Linux
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are files that have a period before them.
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If you do ls-alhon my home directory where we are,
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we can see that we now see bash history and bash profile,
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bash RC, bash logout, all that good stuff.
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We're going into this because you're going to
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use the ls command constantly,
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especially when you're looking at file permissions,
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you'll use this command more than
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the other command in Linux.
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It's very helpful to know,
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even just to know it for
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professional use beyond the exam.
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Let's go ahead and move on to the next command.
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The next command we're going to look at is
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the make directory command,
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which is actually abbreviated as mk dir.
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We've previously covered how to create files,
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but we haven't really gone into creating
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directories and the way that we do this,
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by using the make directory command.
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For instance, in this directory in my cd home,
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so we're in home rob.
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We'll start here. We'll make a directory and we'll just
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call this directory somedir.
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Now we do an ls- al.
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In my system here,
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we can see down here that we have somedir here.
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Notice also when we create the directory that
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it has a d over here in the permissions,
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but right below at some file doesn't have that.
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This d indicates it's a directory that we created.
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We can also create a whole directory structure.
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We can create a directory with empty subdirectories
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underneath it if we know
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the directory structure we want to create.
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We can do all that from scratch,
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but we have to use the - p option,
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p stands for parents,
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and provide the entire directory tree structure.
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If we wanted to do this in my home directory,
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we can make directory dash p and we'll create
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an other directory with a sub-directory,
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dir 1, and another sub-directory,
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dir 2 and another,
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subdirectory dir 3 and there we go.
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Now if you do an ls-alr,
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R is for recursive on home rob other dir.
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What we're going to see is home rob
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other dir with a sub-directory dir
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1. Well, what's in dir 1?
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Home rob of the dir 1 has a sub-directory
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of dir 2 and so on and so forth as we go down there.
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Now if we wanted to actually move files around,
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we can use the mv command.
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MV is short for move and it's used to
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move or also to rename files.
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If we move a file in place without actually
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specifying a different location
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to move it too, it'll rename it.
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The syntax for this is move file
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and then the location that you want to move it to.
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[NOISE] Location.
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If you don't specify location here,
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you just give it another name, it'll give it a new name.
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Let's see this in action.
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Let's go ahead and do an ls here,
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and let's touch a file called original.
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Do another ls, and now we see
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the file right here called original.
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If we wanted to move this
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or actually we're not going to move it, let's rename it.
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We can do move original, new.
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Since we're not specifying a new location,
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we're not specifying a path, its just going to
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rename that file in the directory that it's in.
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If we do an ls, where we saw original before,
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now we see new and that's what you need to do with that.
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What we can also do is move the file by
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specifying new location. Let's do real quick.
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Let's look in temp. In the temp directory,
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we see a bunch of stuff, but these are all directories.
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These aren't actually files.
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We just see a bunch of directories here.
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We see some hidden files too, but that's fine.
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What we can do is we can move our new file that lives
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here into temp by doing
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move new and then specifying temp.
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Now we do an ls on temp,
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we can see that we have the new file
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and that's been moved there.
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If you do an ls on home,
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rob or just do an ls on
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tilter I can see
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that the new file doesn't live here anymore,
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it now lives in temp because we've
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picked it up and moved it.
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We'll see how we can copy things here in just a minute.
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But we can also move
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that file back and rename it at the same time.
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For instance, if we want to move the file
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back from temp new,
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we want to move it back to home rob original,
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so we're removing it, we're also
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renaming it to original when we want to move it.
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When we move it over, we can do this.
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Now when we do an ls on home rob,
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we can see the file has been moved back
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and it's been renamed to original.
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The last command we're going to look
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at today is the copy command.
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The copy command is used to copy files and directories.
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CP is the copy command. That's short for copy.
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The syntax is copy file or directory,
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and then the place that you want to copy it to.
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For instance, we can go ls
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home rob again and we see all our files here.
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If we want to copy the original file back to temp,
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let's just do this cp home,
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rob original and then
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we're going to specify we're
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copying it to the temp directory.
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Now if you do an ls on temp, we see it there.
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If we do ls on home rob,
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it's also still there because we
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just copied it, we haven't moved it.
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If we want to copy a directory though,
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we got to do the -r option.
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If we do an ls on home rob some directory,
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ls-al home, rob some directory.
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We can see that that is there and it is
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a directory file and this is the contents of it.
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If we want to copy it all we have to do copy - r,
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that's the recursive option and we'll do home rob
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somedir to temp and keep in mind,
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before we do this, let's actually look at the timestamp.
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Let's say Control C and do an ls on somedir.
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I'll do an ls-l on subdir
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there and we can see the timestamp on
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it and we see
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that the timestamp on this subdirectory recruiter is 744.
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Now if we try and do a copy-r of this directory from
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home rob somedir over to the temp directory.
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Now we do an ls-ald on temp, somedir.
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We see that that's there but
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look at the timestamp has changed.
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It changed from 1744 to 1748.
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The way that we get around this is by adding
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the a option to the copy.
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What we'll do now is we'll copy
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the other directory instead of sub directory.
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You do copy rob other dir to temp.
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Before we do that let's
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Control C out of this and we'll do
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an ls-ald on home rob other dir.
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We can see that was also created at 1744.
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Now when we do a copy-ar on home rob other dir to temp,
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we do an ls dash, ald on temp,
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other dir, we can see that
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the timestamps stays the same.
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Copy-ar retains the permissions,
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ownership and timestamps when you copy
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files and that is sometimes very important.
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But with that, we've reached the end of this lesson.
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In this lesson, we covered performing operations on
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files and directories and we use the commands ls,
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make directory, move and copy.
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Thanks so much for being here and I look
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forward to seeing you in our next lesson.
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