Linux.Desktop.Hacks [Electronic resources] نسخه متنی

Hack 65. Put Screenshots Automatically on the Web

Show off to the world what
you're up to.

This little hack is fun. It does not
improve system performance in
any way, but it allows you to share with the world what
you're currently doing. This hack is a perfect way
for you to demonstrate how cool your Linux desktop is by
automatically taking screenshots of your desktop and uploading them
to a web server.

The script this hack uses to upload the screenshot is written in Perl
and requires Net::FTP, a web server, and a simple
program called scrot; all of these are freely
available online.

8.12.1. Installing scrot

You can find scrot, a command-line screen-capture tool (similar
to import, which is included with ImageMagick), at
http://linuxbrit.co.uk/scrot/.
Extract, compile, and install the software with these few commands:

foo@bar:~$ wget http://linuxbrit.co.uk/downloads/scrot-0.8.tar.gz
foo@bar:~$ tar -zxvf scrot-0.8.tar.gz
foo@bar:~$ cd scrot-0.8
foo@bar:~$ ./configure
foo@bar:~$ make
foo@bar:~$ su -c "make install"

With scrot installed, you can use it to take
screenshots anytime you want; just find the nearest terminal and type
scrot. For more information on
scrot, see the manpage.

Perl is likely to be installed already on your Linux system, but if
it isn't, you should use your
distribution's installation tool to install it. In
addition to the stock Perl installation, you also need the
Net::FTP module that you can install by using
CPAN, Perl's module repository:

foo@bar:~# perl -e shell -MCPAN
foo@bar:~# install Net::FTP

8.12.2. The Code

This is where all the magic is. Just write each line into your
favorite text editor, whether it is emacs or
vim or something else, and save it as
autoscreenshot.pl in
$localfolder:

#!/usr/bin/perl -w 
use Net::FTP; # Start FTP 
## Define your variables 
$delay = "60"; # Set the screen captures in seconds 
$quality = "50"; # Set the quality of the screenshot
$thumb = "25"; # Set percentage of the thumbnail produced 
$server = "your.server.com"; # Hostname of the server 
$username = "username"; # Put your username for the server here 
$password = "password"; # Put your password for the server here 
$serverfolder = "/home/me/www"; # This is the folder that you want the pictures to 
end up in 
$localfolder = "/home/me/autoscreensnap"; # This is the folder in which you are 
going to locally save the screenshots 
while( ) 
{ 
system("scrot $localfolder/currentscreen.jpg --thumb $thumb --quality $quality"); 
# Let's take the screenshot
$ftp = Net::FTP->new($server, Debug => 0); # Connect to FTP server 
$ftp->login($username, $password); # Let's log in 
print "OK Connected \n"; 
$ftp->cwd($serverfolder); # Change to the directory you want uploaded image to 
be in 
print "OK Changed directories \n"; 
$ftp->binary( ); # Set binary mode so the picture works 
$ftp->delete("$serverfolder/currentscreen.jpg"); # Delete old screenshot
$ftp->delete("$serverfolder/currentscreen-thumb.jpg"); # Delete old thumbnail 
print "Deleted old screenshots\n"; 
$ftp->put("$localfolder/currentscreen.jpg"); # Uploading... 
$ftp->put("$localfolder/currentscreen-thumb.jpg"); #Upload some more.. 
print "OK Finished uploading files\n"; 
$ftp->quit; # Close session 
print "Sleeping for $delay seconds\n\n"; 
system("sleep $delay"); 
}

The first half of the script is just to define all your variables. It
is safe to change these and it is recommended that you do change them
to suit your needs. These options include the following:

$delay

Determines how long the script will wait, in seconds, until it
repeats the loop.

$quality

Controls the quality of the screenshot that will be taken. I suggest
you use a low number so that it doesn't take long to
upload or download the screenshot.

$thumbnail

Defines what percentage of your resolution the thumbnail should be.

$server

The host of your web server; hopefully it has FTP running on it.

$serverfolder

The folder on your web server that will be accessible by the World
Wide Web.

$localfolder

Represents the folder where you are going to store the screenshots. I
recommend you put it in your home folder just to make everything
easy.

The second half of the script uses a loop that repeats itself over
and over again. The first command tells the script to use
scrot to take a screenshot and create a
thumbnail. Then it connects to the web server and changes to a
directory visible on the Internet. Once the script has completed, it
deletes any old screenshots and thumbnails and uploads the new ones.
After it completes this job, it sleeps for 60 seconds by default
(this is adjustable) and then continues the loop once again.

8.12.3. Running the Code

To run the script first change the directory to
$localfolder. Your
autoscreenshot.pl script should be sitting in
this folder. Now you can run it in two different ways. You can run
the script independently with the following commands:

foo@bar:~$ chmod 777 autoscreenshot.pl
foo@bar:~$ ./autoscreenshot.pl

An alternative is to run it with the Perl interpreter:

foo@bar:~$ perl autoscreenshot.pl

John Cheng