代作Shell Programming 留学生程序、代做Shell命令、代做国外shellProgramming

日期：2018-05-28 12:44

CSCB09H3: Software Tools and Systems Programming (Summer 2018)

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CSCB09H3: Software Tools and Systems Programming

Assignment 1: Shell Programming

Due Date: 11:59 pm Thursday, May 31, 2018

Worth: 12% of your final grade.

Overview:

In this assignment you will write three shell programs that operate on a collection of photographs. The

first program, mkpics will generate an html file to display a table of photos. The second, filepics will

organize the photos into directories by the date that they were created. The third program mkpics2 will

extend mkpics to handle the directories created by the second program.

To get full marks, your code must be well-documented, and use idiomatic shell programming. This

means that you should avoid creating processes when you don't need to. It also means that you should

use the special variables when appropriate. Using ls and cat in your programs is not allowed.

All programs are to be written using #!/bin/sh to be run on mathlab or the lab machines.

Setting up your working environment:

Follow the instructions carefully, so that we receive your work correctly. The instructions below will

setup your svn work environment. The final submission will include the three shell scripts (mkpics,

filepics, mkpics2).

Your first step should be to log into mathlab or any of the lab machines in BV 473 using your UtorID

and password. Create a directory called cscb09 (directories are created using mkdir). Change into that

directory (using cd). Verify that you are actually in the right directory (running pwd should return

/courses/courses/cscb09s18/your_utorid/cscb09). The following commands should accomplish

the above:

mkdir ~/cscb09_space/cscb09

cd ~/cscb09_space/cscb09

pwd

Now check out your SVN repo using the following command:

svn co svn+ssh://your_utor_id@mathlab.utsc.utoronto.ca/svn/cscb09s18/your_utor_id

You will be asked for a password which is your usual utorid password. The repository we have created

is empty, so all you will see after checking out you repo is an empty directory (inside your

/courses/courses/cscb09s18/your_utorid/cscb09 directory) with the name of your UtorID. (Use

ls to check that the directory is there). This directory is a working copy of your svn repository. Start by

changing into the directory and create a new directory called a1 by executing the following commands:

cd ~/cscb09_space/cscb09/your_utor_id

mkdir a1

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Next you want to add your new directory a1 to the repository (using svn add), check in this change to

the svn server (using svn ci), and change into your new a1 directory:

svn add a1

svn ci -m "I have created the a1 directory"

cd a1

For this assignment you will be asked to hand in three different files mkpics, filepics and mkpics2.

These three files are the three shell scripts we are asking you to implement as part of this assignment and

these files should be submitted in the a1 directory using svn add and then svn ci the change.

Script 1: mkpics -- creating a web page of photographs (35%)

The program mkpics will write to standard output valid html that will display a table of photos. The first

command line argument to mkpics is the number of columns in the table, and the remaining arguments

are the files to be displayed.

Details:

? If there are not enough pictures to fill all of the rows, then the incomplete row may be the first

row or the last row.

? Please include the height=100 attribute in each img tag in your table so that the page will be

displayed reasonably.

? There does not need to be any fancy formatting of the table or any additional text except for the

title.

? Your html output does not need to look pretty but should be readable. In other words don't worry

too much about indentation and white space when writing the output.

? Your program should only include jpeg pictures in the table. It should verify that a file is a

picture by checking the file type using the file program.

? Errors should be handled reasonably.

o Your program should not crash.

o It should write all error messages to standard error and exit in appropriate situations.

o It should handle 0 or more pictures.

o If your program is run with an argument (other than the first one) that is not a jpeg

picture, it should report this to standard error with an appropriate message and continue

creating the table using the valid filenames. If none of the arguments are valid filenames

your program should create and write an empty table to standard output.

A possible html file that might be produced by your program is shown:

<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN">

<html>

<head>

<title>Pictures</title>

</head>

<body>

<h1>Pictures</h1>

CSCB09H3: Software Tools and Systems Programming (Summer 2018)

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<table>

<tr>

<td><img src="pictures/IMGP0959.jpg" height=100></td>

<td><img src="pictures/IMGP2739.jpg" height=100></td>

<td><img src="pictures/IMGP2850.jpg" height=100></td>

</tr>

<tr>

<td><img src="pictures/IMGP3064.jpg" height=100></td>

<td><img src="pictures/IMGP3069.jpg" height=100></td>

<td><img src="pictures/IMGP3528.jpg" height=100></td>

</tr>

</table>

</body> </html>

Some Helpful Tips

A directory of images that you may use for testing can be found at:

/courses/courses/cscb09s18/nizamnau/a1/pics

To check that your output produced the desired results, you can open the html files that your script

creates in a web browser to verify that the formatting is as expected.

For this assignment you will likely need to do some simple integer arithmetic on variables. As the shell

naturally operates on strings, not integers, you will need the command expr. See the man pages for how

to use it. As an example, the following will assign the result of 5+3 to the variable y.

y=`expr 3 + 5`

Script 2: filepics -- sorting photos into directories (35%)

Digital cameras typically add data to a jpeg file known as Exif (Exchangeable Image File) data. This

data includes the time the picture was taken or generated.

In /courses/courses/cscb09s18/bin you will find a program called exiftime that prints to standard

output the time information stored in a jpeg file. To use this program (without typing the full path

everytime) you will need to add /courses/courses/cscb09s18/bin to your PATH variable.

The example below shows how to run exiftime (before adding its location to PATH) on an image file

called pic1.jpg and the output it produces:

/courses/courses/cscb09s18/bin/exiftime -tg pic1.jpg

Image Generated: 2006:07:09 00:03:29

The filepics program will take an existing directory as an argument. For each picture in that directory,

filepics will use exiftime to get the time that the picture was generated. It will move the pictures to

directories by year, and within year by month. The year directories will be subdirectories of the directory

from which the script was run.

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For example, if the directory vacation contains the following files with the exiftime -tg output

shown beside them:

IMGP2739.jpg: Image Generated: 2012:01:02 16:14:03

IMGP2850.jpg: Image Generated: 2011:01:01 18:17:44

IMGP3064.jpg: Image Generated: 2011:03:10 11:39:40

IMGP3069.jpg: Image Generated: 2011:03:10 12:15:24

Then the result of running filepics vacation would be the following:

Details:

? Your program will create the appropriate directories, but should create only the directories that

are needed.

? Your program should do reasonable error handling.

? Any non-picture files in the original directory should be ignored.

Hint: You may find the cut program useful for this script.

Script 3: mkpics2 -- extending mkpics (30%)

The mkpics2 program is a modified version of your mkpics program that takes the number of columns

and a directory as an argument instead of the number of columns and list of files. The directory is the

root of a tree of ``filed" pictures from running filepics. It contains subdirectories by year which

themselves contain subdirectories by month which contain the pictures.

Your program will write to standard output one html document that has a table of photos for each year.

Each table will be preceded by an <h2> header with the year. All of the details from part 1 apply to this

program as well.

Running mkpics2 2 . on the tree above would produce the following html page.

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<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN">

<html>

<head>

<title>Pictures</title>

</head>

<body>

<h1>Pictures</h1>

<h2>2012</h2>

<table>

<tr>

<td><img src="2012/01/IMGP2739.jpg" height=100></td>

</tr>

</table>

<h2>2011</h2>

<table>

<tr>

<td><img src="2011/01/IMGP2850.jpg" height=100></td>

<td><img src="2011/03/IMGP3064.jpg" height=100></td>

</tr>

<tr>

<td><img src="2011/03/IMGP3069.jpg" height=100></td>

</tr>

</table>

</body>

</html>

Again, your program should do reasonable error checking. You'll notice that this instruction is quite

different from what you may have encountered in your previous CS courses. In B09, we will often not

be specifying exactly what is reasonable error checking or answering questions about every specific

case. You must make your own judgement calls about what assumptions are acceptable and what error

checking is required. As a general rule, a user should not be able to crash your program and you should

provide the user with a helpful usage message when the command-line arguments are incorrect.

Learning objectives

? Shell control structures and variables

? Shell control structures and variables

? Running external programs from a shell program

? Shell quoting

? Working with files and directories using the shell

CSCB09H3: Software Tools and Systems Programming (Summer 2018)

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What to hand in

We will look for the following three files in your svn repository (based on your UtorID):

? mkpics

? filepics

? mkpics2

Don't forget to run svn add and svn ci for the three shell scripts after adding them to your a1 directory.

Please remember to make your shell scripts executable by ensuring that the first line is #!/bin/sh.

You are strongly encouraged to take advantage of the version control system and commit your work

frequently so that you can keep track of your progress. Please note that it is perfectly fine (and even

recommended) that you keep any additional files related to this assignment under version control. The

markers will simply ignore these files.