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OK so let's write some script where we can break this file system does operate this create a file called

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file test that age and that as you deal with siobhán bin bash.

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So what is wanted in this script for a provided file print summary

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of vote permissions user has granted

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but best be to do some examples to be sure that you fully understand what is wanted.

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So we roll around the script to read one argument some file name or a file path.

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And as a result we got.

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If that file is for us readable right to go our executor will

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so we receive some eco C'mon some message which is which says if the file is readable ridable or actable.

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Now we can start with.

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I will check because we want only one and one 5.

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So if number of our demands is not equal to 1

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we can bring in

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provide exactly one I will land and you can also exit here with startles one.

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Now you can also assign a variable.

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So in variable called File we are assigning a value of argument one.

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First I will add some command or so here variable assignment.

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Now we can check if dead file the first and only one argument is an existing file.

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So right in square brackets

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an operator and then file file variable.

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If that file exists we should do right.

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If you can read override or exec a file for death I will create new variables which will keep value

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yes or no.

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So some command here.

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Default variables and I will start the read variable.

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So Vita read

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equals two values.

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No.

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Right right equals two value.

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No.

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And exec equals to.

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No.

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All of them will have a value.

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No.

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And that is not true.

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We will change it later.

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Now we can check if file is readable.

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So if break bracket and use our operator for checking if the file is readable

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if a file is readable we can change the value of a variable to read to S..

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That means that the file is readable.

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Now we will check if file is right to go and for that we will use w operator.

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So check if he's right to go if and in square bracket we are using W operator

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and if that file is a right to go we need to change the value of variable.

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Write to us

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and check is if that file is executable.

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So check if file is.

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So for doing this check we will use operator X and of course if you need to assign value yes to variable

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via exec.

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Now we have or they don't need it.

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So we can print to user some summary some summary so you can Bryde eco

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but maybe Firstly I write some command here write somebody to user

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and on the first go here we will write

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read.

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And here we are putting the value of a variable.

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What I did.

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So it may be yes or no on the next line we will print value of variable.

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Var right.

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And on the next line we will print a value of variable var.

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So X exec to double Vajra and

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and maybe we can do also some fancy either for that

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so we can use another e-com

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file and we can based out both of the file variable

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but that's not all.

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We finished only the part for the case that file exist.

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If file doesn't exist.

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We can print something as vote file variable does not exist.

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So right you go to sign the file does not exist.

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Now we are done.

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So you can save descript

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ground with permission

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and we can meet but firstly create some test file using Dutch.

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Dutch Hello.

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Dot text and also create some testing directories so M-K dear

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directory.

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Now we see that we have one script one file and one directory.

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So now around the script firstly without an audible one works fine.

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Now we can use Hello text as an argument and we can see that we have read and write permissions.

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Great.

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So now we just grand exit could permission to that file Hello dot text and run the script again.

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Great.

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It works.

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We can see that we have also exit permissions.

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Now we can try to provide file with Hobart for example been beshe great.

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It also works.

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But what would happen if we specify our directory

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we see message that dedicatory doesn't exist which is correct such a file really doesn't exist.

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Same would be definitely for directory for example been

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so ran script again vate directory called Ben

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Oh no not been very sorry.

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It's been only been you see that been doesn't exist but I don't like that behavior.

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It would be much better to print to or that the argument provided is a directory Dubin is a directory.

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So open our script again and we can change their behavior for a case when file does not exist.

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But it is directory instead.

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So open file

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and under our state command

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we'll do some new if statement and we'll ask if we do

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file if the of file variable is not a directory and if it is a dedicatory we will print that value of

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an argument is a directory.

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Otherwise we will write that file does not exist.

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So we can also prebend before the value of variable file file.

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So file and devolve or variable file does not exits.

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And now we can save the script and we can try to run it again at agreement.

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It's like a big and we see now that slash and burn is directory.

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Great.

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So now we have break this file.

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Test operators and I can mention that they are usually used.

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And it is good to know them especially they are used for some backup scripts where we can for example

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check if destination for that exists and if not we can create it as backup is sometimes done to timestep

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folders.

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You can imagine a situation in a company which does daily backup and for current day it is already some

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backup done.

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So it can be time consuming to do because again if it is already done by checking if times then for

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the exits and it has some file in it's v. Vaughn do any more useless copying of files.

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So thanks for watching and see your next lecture.