Description
Before the lab you should re-read the relevant lecture slides and their accompanying examples.
Create a new directory for this lab called lab03, change to this directory, and fetch the provided code for this week by running these commands:
$ mkdir lab03
$ cd lab03
$ 2041 fetch lab03
Or, if you’re not working on CSE, you can download the provided code as a zip file or a tar file.
Write a shell script jpg2png.sh which converts all images in JPEG format in the current directory to PNG format.
You can assume that JPEG files and only JPEG files have the suffix jpg.
If the conversion is succesful the JPEG file should be removed.
Your script should stop with the error message shown below and exit status 1 if the PNG file already exists.
| $ wget https://cgi.cse.unsw.edu.au/~cs2041/20T2/activities/jpg2png/images.zip
$ unzip images.zip Archive: images.zip inflating: Johannes Vermeer – The Girl With The Pearl Earring.jpg inflating: nautilus.jpg inflating: panic.jpg inflating: penguins.jpg inflating: shell.jpg inflating: stingray.jpg inflating: treefrog.jpg $ ./jpg2png.sh $ ls ‘Johannes Vermeer – The Girl With The Pearl Earring.png’ jpg2png.sh panic.png shell.png treefrog.png images.zip nautilus.png penguins.png stingray.png $ wget https://cgi.cse.unsw.edu.au/~cs2041/20T2/activities/jpg2png//penguins.jpg $ ls ‘Johannes Vermeer – The Girl With The Pearl Earring.png’ jpg2png.sh panic.png penguins.png stingray.png images.zip nautilus.png penguins.jpg shell.png treefrog.png $ ./jpg2png.sh penguins.png already exists |
When you think your program is working, you can use autotest to run some simple automated tests:
$ 2041 autotest jpg2png
Autotest Results
95% of 447 students who have autotested jpg2png.sh so far, passed all autotest tests.
97% passed test jpg2png_0
96% passed test jpg2png_1
97% passed test jpg2png_2
96% passed test jpg2png_3
Hints
The program display(1) can be used to view image files
The program mutt(1) can be used to send mail from the command line including attachments, for example:
$ echo ‘Penguins are cool.’|mutt -s ‘penguins!’ -e ‘set copy=no’ -a penguins.png
There is no autotest and no automarking of this question.
When you are finished working on this exercise, demonstrate your work to another student in your lab and ask them to enter a peer assessment. It is preferred you do this during your lab, but if this is not possible you may demonstrate your work to any other COMP(2041|9044) student before Tuesday 23 June 17 59. Note, you must also submit the work with give.
Write a shell script date_image.sh which, given a list of image files as arguments, changes each file so it has a label added to the image indicating the time it was taken. You can assume the last-modification time of the image file is the time it was taken.
So for example if we run these commands:
$ cp -p /web/cs2041/20T2/activities/date_image/penguins.jpg .
$ ls -l penguins.jpg
-rw-r–r– 1 andrewt andrewt 58092 Mar 16 16:08 penguins.jpg
$ ./date_image.sh penguins.jpg
$ display penguins.jpg
There is no autotest and no automarking of this question.
Andrew regularly spends time far from the internet and streaming music services such as Spotify, so he has a large collection of MP3 files containing music.
Andrew has a problem: the ID3 tags in the MP3 files in his music collection are incorrect. Unfortunately Andrew’s favourite player software organises music using the information from these ID3 tags. Your task it to fix Andrew’s problem by set the ID3 tags to the correct values. Fortunately the correct value for the tags can be retrieved from the file names and the names of the directories the files are in.
Your task is to write a shell script tag_music.sh, which sets the ID3 tags of MP3 files using the information from file names and directory names.
You’ll first need to make a copy of Andrew’s music collection.
Download music.zip, or copy it to your CSE account using the following command:
$ cp -n /web/cs2041/20T2/activities/tag_music/music.zip .
You assume the names of files and directories follow a standard format. You can determine this format by look at ethe files in Andrew’s music collection.
$ unzip music.zip Archive: music.zip creating: music/ creating: music/Triple J Hottest 100, 2007/ inflating: music/Triple J Hottest 100, 2007/2 – Straight Lines – Silverchair.mp3 inflating: music/Triple J Hottest 100, 2007/10 – Don’t Fight It – The Panics.mp3 …
The command id3 can be used to list the value of ID3 tags in an MP3 file. For example:
$ id3 -l ‘music/Triple J Hottest 100, 2013/1 – Riptide – Vance Joy.mp3’ music/Triple J Hottest 100, 2013/1 – Riptide – Vance Joy.mp3:
Title : Andrew Rocks Artist: Andrew
Album : Best of Andrew Year: 2038, Genre: Unknown (255) Comment: Track: 42
But, as you can see, the ID3 tags of this music file have been accidentally over-written. The ID3 tags should be:
$ id3 -l ‘music/Triple J Hottest 100, 2013/1 – Riptide – Vance Joy.mp3’ music/Triple J Hottest 100, 2013/1 – Riptide – Vance Joy.mp3:
Title : Riptide Artist: Vance Joy
Album : Triple J Hottest 100, 2013 Year: 2013, Genre: Unknown (255) Comment: Track: 1
Fortunately, all the information needed to fix the ID3 tags is available in the name of the file and the name of the directory it is in.
You will write a shell script tag_music.sh which takes the name of 1 or more directories as arguments and fixes the ID3 tags of the all MP3 files in that directory. For example:
| $ ./tag_music.sh ‘music/Triple J Hottest 100, 2015’
$ id3 -l ‘music/Triple J Hottest 100, 2015/4 – The Less I Know the Better – Tame Impala.mp3’ music/Triple J Hottest 100, 2015/4 – The Less I Know the Better – Tame Impala.mp3: Title : The Less I Know the Better Artist: Tame Impala Album : Triple J Hottest 100, 2015 Year: 2015, Genre: Unknown (255) Comment: Track: 4 $ ./tag_music.sh music/* $ id3 -l ‘music/Triple J Hottest 100, 1995/10 – Greg! The Stop Sign!! – TISM.mp3’ music/Triple J Hottest 100, 1995/10 – Greg! The Stop Sign!! – TISM.mp3: Title : Greg! The Stop Sign!! Artist: TISM Album : Triple J Hottest 100, 1995 Year: 1995, Genre: Unknown (255) Comment: Track: 10 $ id3 -l ‘music/Triple J Hottest 100, 1999/1 – These Days – Powderfinger.mp3’ music/Triple J Hottest 100, 1999/1 – These Days – Powderfinger.mp3: Title : These Days Artist: Powderfinger Album : Triple J Hottest 100, 1999 Year: 1999, Genre: Unknown (255) Comment: Track: 1 $ id3 -l ‘music/Triple J Hottest 100, 2012/2 – Little Talks – Of Monsters and Men.mp3’ music/Triple J Hottest 100, 2012/2 – Little Talks – Of Monsters and Men.mp3: Title : Little Talks Artist: Of Monsters and Men Album : Triple J Hottest 100, 2012 Year: 2012, Genre: Unknown (255) Comment: Track: 2 |
Your script should determine Title, Artist, Track, Album, and Year from the directory and filename.
Your script should not change the Genre or Comment fields.
Hints
$ man id3 …
cut almost works for extracting Title and Album from the filename.
Handling the few MP3 files correctly where using cut doesn’t work will be considered a challenge exercise.
It can be difficult debugging your script on Andrew’s music collection. In cases like these it usually worth creating a smaller data set for initial debugging. Such a tiny data set is available in tiny_music.zip if you want to use it for debugging. This dataset is used in the first autotests.
2020/7/24first autotests.
Download tiny_music.zip, or copy it to your CSE account using the following command:
$ cp -n /web/cs2041/20T2/activities/tag_music/tiny_music.zip .
| $ unzip tiny_music.zip Archive: tiny_music.zip creating: tiny_music/ creating: tiny_music/Album1, 2015/ inflating: tiny_music/Album1, 2015/2 – Little Talks – Of Monsters and Men.mp3 inflating: tiny_music/Album1, 2015/1 – Riptide – Vance Joy.mp3 creating: tiny_music/Album2, 2016/ inflating: tiny_music/Album2, 2016/2 – Royals – Lorde.mp3 inflating: tiny_music/Album2, 2016/1 – Hoops – The Rubens.mp3
$ id3 -l tiny_music/*/*.mp3 tiny_music/Album1, 2015/1 – Riptide – Vance Joy.mp3: Title : Andrew Rocks Artist: Andrew Album : Best of Andrew Year: 2038, Genre: Unknown (255) Comment: Track: 42 tiny_music/Album1, 2015/2 – Little Talks – Of Monsters and Men.mp3: Title : Andrew Rocks Artist: Andrew Album : Best of Andrew Year: 2038, Genre: Unknown (255) Comment: Track: 42 tiny_music/Album2, 2016/1 – Hoops – The Rubens.mp3: Title : Andrew Rocks Artist: Andrew Album : Best of Andrew Year: 2038, Genre: Unknown (255) Comment: Track: 42 tiny_music/Album2, 2016/2 – Royals – Lorde.mp3: Title : Andrew Rocks Artist: Andrew Album : Best of Andrew Year: 2038, Genre: Unknown (255) Comment: Track: 42 $ ./tag_music.sh tiny_music/* $ id3 -l tiny_music/*/*.mp3 tiny_music/Album1, 2015/1 – Riptide – Vance Joy.mp3: Title : Riptide Artist: Vance Joy Album : Album1, 2015 Year: 2015, Genre: Unknown (255) Comment: Track: 1 tiny_music/Album1, 2015/2 – Little Talks – Of Monsters and Men.mp3: Title : Little Talks Artist: Of Monsters and Men Album : Album1, 2015 Year: 2015, Genre: Unknown (255) Comment: Track: 2 tiny_music/Album2, 2016/1 – Hoops – The Rubens.mp3: Title : Hoops Artist: The Rubens Album : Album2, 2016 Year: 2016, Genre: Unknown (255) Comment: Track: 1 tiny_music/Album2, 2016/2 – Royals – Lorde.mp3: Title : Royals Artist: Lorde Album : Album2, 2016 Year: 2016, Genre: Unknown (255) Comment: Track: 2 |
When you think your program is working, you can use autotest to run some simple automated tests:
