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- In this video, I will
tell you about permissions

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the basic permissions in Linux.

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There's three of them.

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We have read, we have
write, and we have execute.

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Now, when you are going to
assign these permissions

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using the chmod command,

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you are probably going to use
what we call the octal mode.

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That's a number

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and you are going to assign
these numbers to ugo,

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ugo, user, groups and others.

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I'll tell you more about it later,

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but I already want to give you the number.

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Read is four, write is
two, and execute is one.

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Now, while assigning these permissions,

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it is essential to understand

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what these permissions are doing

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on files or on directories.

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Well, if you have read on a
file, guess what you can do.

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You're right, that allows you
to actually read the file.

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Read the file, in computer technology,

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means you can open the file in memory

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and do whatever you want to do with it.

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And how about read on a directory?

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Well, if you have read on the directory

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that means that you can list
files in that directory.

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Now we have write.

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If you have write on files

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then you can actually modify your files.

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If you have write on the directory

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that allows you to add or delete
files from that directory.

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And that is something
that you should remember.

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Deleting files is a directory operation,

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not a file operation, so
you don't need permissions

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on the file in order to delete it.

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You just need permissions

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on the directory that contains the file.

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And last, there is execute.

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Execute is a very important
permission in Linux

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because that's the permission
that makes Linux secure.

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Execute is what you need
in order to run a command.

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If you don't have execute permissions

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you cannot run the file.

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That is what makes Linux a
very secure operating system.

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And that's also the main reason why Linux,

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you don't need any antivirus or whatever,

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because execute doesn't come by default.

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There is also execute on directories,

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and that means that you can cd

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and change into the directory.

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Now, in order to work with permissions,

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you need to assign these
permissions to the owner.

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Linux works with ugo, as I mentioned,

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user, group and others.

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User is the user who is owner,
group is the group owner,

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and others, that is everybody else.

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And I will show you next how to do that.

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So let me summarize
what we have just seen.

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Basic permissions is what it's all about

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and you can set basic permissions to files

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as well as directories.

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And there are three basic permissions.

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To start with, there is read,
with the octal value four.

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And read, if you apply it on files,

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means that you can read
the contents of a file

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and on directories, it
means that you can list

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the contents of directories with ls.

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Just make sure to understand
that read on directory

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does not mean that you can read
any files in that directory,

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because that is decided by the
individual file permissions.

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Next, there is write, write on files

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means that you can modify
the contents of the file

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and write on the directory means

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that you can add and remove
files from the directory.

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The thing to realize here is that

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deleting a file is a directory operation.

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So that means if you have
write on the directory

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you can delete it

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no matter which permissions
you've got on the file.

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Next, we have execute.

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Execute on files means
that you run the file

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if it contains executable code.

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And if you have execute on
the directory, then it means

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that you can change into the
directory using the cd command.

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That's all.

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In the next video, I will
show you how to apply these.