Archive
Backup your Gmail messages
You must have heard about the Gmail incident that occurred today. 150,000 users found their e-mail accounts reset.
Remember the motto: “Shit happens.” Gmail is not an exception, so make regular backups of your mails.
Short version
Install Thunderbird, link it with your Gmail account with IMAP, and let Thunderbird synchronize your mails regularly.
Longer version
- install Mozilla Thunderbird
- Thunderbird 3.x has built-in support for Gmail, so it’s very easy to set up an account that links Thunderbird with your Gmail account. Create an IMAP account, not a POP3. You can also refer to this post for more info.
- Don’t be greedy, don’t try to download all your mails in one session. Give it some days, otherwise you risk that Google shuts your account down because of the high load. Download about max. 1 GB a day.
More security
If you make a local backup of your mails, you should protect it. If someone gets to your machine, (s)he can read your mails, right? I suggest storing this backup on a TrueCrypt volume [more info here]. On my laptop, I have an encrypted partition of 20 GB, and I keep my backups there.
Another advantage
If you download your mails with Thunderbird, it has another advantage. As pointed out in this post, with Thunderbird you can sort your messages in descending order by size, thus you can remove messages with large attachments easily. If your Gmail account is 90% full, consider this method.
Conceptual drawings for Star Wars
Here is a nice video with the conceptual drawings of Ralph McQuarrie. “Ralph McQuarrie (born June 13, 1929) is a conceptual designer and illustrator who designed Star Wars (all of the original trilogy), the original Battlestar Galactica (TV), E.T. the Extra-Terrestrial and Cocoon, for which he won an Academy Award.” (from wikipedia)
Home page of the artist: http://www.ralphmcquarrie.com.
I found this video in this post (in Hungarian).
mp3 tag editor
“EasyTAG is a utility for viewing and editing tags for MP3, MP2, MP4/AAC, FLAC, Ogg Vorbis, MusePack, Monkey’s Audio and WavPack files. Its simple and nice GTK+ interface makes tagging easier under GNU/Linux or Windows.” (source)
Installation:
sudo apt-get install easytag
With EasyTAG you can process your mp3 files in batch mode. For instance, you can set the album name for several files with just one click.
Tip: if you want to edit the MP3s in the current directory, launch the application with “easytag .“.
Copy and paste the output of a program
It is a common task to copy the output of a program/script and paste it somewhere else. If the output is short (just some lines), we can select the text easily with the mouse. What about longer outputs?
Old method
Until now I’ve been using the following method:
./produce-long-output >a(redirect the output to a temporary file)gedit a(open the temp file with a text editor)- CTRL+A (select the whole text)
- copy selected text to the clipboard
- paste text to somewhere else
rm a(remove the temp file)
New method
Recently, I discovered some tools (xclip and xsel) that can copy a text to the clipboard. With them, it is unnecessary to use a temporary file.
./produce-long-output | xsel
It’ll copy the text to the “primary” clipboard that you can paste with the middle mouse button. If you prefer pasting with Shift + Insert, then copy texts to the 3rd clipboard (it is simply called “clipboard”).
./produce-long-output | xsel -b
Life has become a little bit less complicated :)
Copy string to X clipboard in shell
This entry is based on the post Copy Shell Prompt Output To Linux / UNIX X Clipboard Directly.
Problem
Under Linux, you want to copy a given text to the X clipboard. How to do that?
Three different clipboards
First of all, we should know that under X there are three clipboards :)
- “primary”: The primary one’s paste operation is usually accessed with the middle mouse button.
- “secondary”: This one didn’t really work for me…
- “clipboard”: Its paste operation is accessed with Shift + Insert (or right mouse click and Paste in popup menus).
The xclip command
“Reads from standard in, or from one or more files, and makes the data available as an X selection for pasting into X applications. Prints current X selection to standard out.“
Installation:
sudo apt-get install xclip
Copy a string to the clipboard. By default, xclip copies to the “primary” clipboard.
echo "this is a test" | xclip echo "this is a test" | xclip -selection primary echo "this is a test" | xclip -selection p
The three variations are equivalent.
Copy a string to the “clipboard” (3rd clipboard).
echo "another test" | xclip -selection clipboard echo "another test" | xclip -selection c
The two variations are equivalent.
Copy the contents of a file to the clipboard.
cat file.txt | xclip
Print the contents of the clipboard to the standard output.
xclip -o
Of course, you can use redirection.
xclip -o > out.txt
The xsel command
“Retrieve and set the X selection.“
xsel is similar to xclip, but it offers some additional features like append, clear, etc.
Installation:
sudo apt-get install xsel
Copy a string to the primary clipboard (default).
echo "1" | xsel echo "1" | xsel -p
The two variations are equivalent.
Copy a string to “clipboard” (3rd clipboard).
echo "1" | xsel -b
Copy the contents of a file to the clipboard.
cat file.txt | xsel
Print the contents of the clipboard to the standard output.
xsel -o
Homework
Find a solution to copy a string to the “primary” and “clipboard” clipboards, i.e. on both. Hint: “echo homework | xsel -p -b” and “echo homework | xclip -selection p -selection c” won’t work. Post your solution in the comments.
Archives List Generator for wordpress.com
Problem
I wanted to have an “Archives” page that lists the titles of my posts. This way, I could find the post I’m looking for much easier. Unfortunately I didn’t find this functionality on wordpress.com. I was searching for a solution and I found WordPress ListMaker v2. However, the author provides an EXE only and his program requires your username. This is something I would never give out… On the other hand, I use Linux, so I prefer open source solutions.
So I’ve decided to write a Python script that produces an HTML output, similar to WordPress ListMaker v2.
Demo
You can see my Archives list here. It was generated with my script.
Download
Visit https://github.com/jabbalaci/Archives-List-Generator. Source code is here.
Solution
In a previous post I showed how to get the list of your blog posts. This script is an extended version, it simply produces a formatted HTML output.
Usage:
Modify the beginning of the script: precise the address of your blog, your username, password, etc. Then just simply execute the script. You can redirect the output to a file, then paste the contents of the file to your wordpress.com blog.
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cron and crontab
If you want a detailed presentation of the topic, refer to this post. Here I write just a short summary.
Cron is the daemon that executes scheduled commands. Crontab is the program to maintain crontab files for individual users. If we want to schedule a command, we need to use crontab.
List your sceduled tasks:
crontab -l
Edit the list of your sceduled tasks:
crontab -e
Example #1:
* * * * * date >>/tmp/date.log
It will append the date to /tmp/date.log every minute. It can be used for testing to see if you have the rights to schedule cron jobs.
Structure:
{minute} {hour} {day of month} {month} {day of week} {command}
Example #2:
0 22 * * * date >>/tmp/date.log
Meaning: every day at 22h, execute the given task.
Example #3:
0 */2 * * * date >>/tmp/date.log
Execute the task every 2 hours. Notice that the minute must be specified (can be different from 0)! If you write “* */2 * * *“, it will still be executed every minute.
Calling a graphical application from crontab
If you want to launch a GUI application, you’ll get an error message: “Error: Can’t open display:”. To solve this problem, add an extra line to your crontab:
DISPLAY=:0 0 */2 * * * /path/to/gui_app.py >>/tmp/log.txt
Related
Python tutorials of Full Circle Magazine in a single PDF
Please read first the update information at the end of the post.
Description
Full Circle Magazine (FCM) started a Python tutorial series in issue #27. At the time of writing, the current issue is #45, and the tutorial is still there :)
Problem: it would be nice to extract these tutorials from the issues and put them together in a single PDF. Thus, we would have all the tutorials together in one document.
Download
For the lazy pigs, here is the PDF (6 MB). Get it while it’s hot :)
How to produce the single PDF
For those who are interested, here I explain how to produce the single PDF above.
First, download the issues of FCM. I suppose that the required files are named issue27_en.pdf, issue28_en.pdf, …, issue45_en.pdf. Put them in a directory called full-circle.
Here is a CSV file that contains data about which pages to extract from the issues:
# issue; start page; end page 27;7;10 28;7;11 29;7;11 30;7;9 31;8;11 32;8;12 33;8;12 34;8;15 35;10;13 36;7;11 37;7;11 38;7;11 39;7;11 40;8;14 41;8;12 42;8;11 43;7;9 44;7;9 45;7;8
Put this file (download link) to the same directory where the PDF files are. Here, create a subdirectory called pieces. The extracted PDFs will be stored there.
We will use the following Python script to produce the commands that will do the extraction:
#!/usr/bin/env python
# extract.py
f1 = open('python.csv', 'r')
for line in f1:
if line.startswith('#'):
continue
# else
line = line.rstrip('\n')
(issue, start_page, end_page) = line.split(';')
command = "pdftk issue%s_en.pdf cat %s-%s output pieces/%s-python.pdf" % (issue, start_page, end_page, issue)
print command
f1.close()
By executing the script (download link), you will get the following output:
pdftk issue27_en.pdf cat 7-10 output pieces/27-python.pdf pdftk issue28_en.pdf cat 7-11 output pieces/28-python.pdf pdftk issue29_en.pdf cat 7-11 output pieces/29-python.pdf pdftk issue30_en.pdf cat 7-9 output pieces/30-python.pdf pdftk issue31_en.pdf cat 8-11 output pieces/31-python.pdf pdftk issue32_en.pdf cat 8-12 output pieces/32-python.pdf pdftk issue33_en.pdf cat 8-12 output pieces/33-python.pdf pdftk issue34_en.pdf cat 8-15 output pieces/34-python.pdf pdftk issue35_en.pdf cat 10-13 output pieces/35-python.pdf pdftk issue36_en.pdf cat 7-11 output pieces/36-python.pdf pdftk issue37_en.pdf cat 7-11 output pieces/37-python.pdf pdftk issue38_en.pdf cat 7-11 output pieces/38-python.pdf pdftk issue39_en.pdf cat 7-11 output pieces/39-python.pdf pdftk issue40_en.pdf cat 8-14 output pieces/40-python.pdf pdftk issue41_en.pdf cat 8-12 output pieces/41-python.pdf pdftk issue42_en.pdf cat 8-11 output pieces/42-python.pdf pdftk issue43_en.pdf cat 7-9 output pieces/43-python.pdf pdftk issue44_en.pdf cat 7-9 output pieces/44-python.pdf pdftk issue45_en.pdf cat 7-8 output pieces/45-python.pdf
As can be seen, the extraction will be done with pdftk (more info here). Now, these commands are simply printed to the standard output. Here is how to execute them too:
./extract.py | sh
That is, pass the commands to the shell “sh”, which will execute them line by line.
Okay, now we have the pieces in the directory “pieces”. Enter the directory “pieces” and join the PDFs:
pdftk *.pdf cat output all.pdf
Known issue
Well, to tell the truth, this method will produce a huge single PDF. The extracted pieces are also very big (5 to 10 MB), and the final PDF is about 130 MB! So actually I used Adobe Acrobat 8 Professional to merge the pieces with the conversion setting “Smaller File Size”. Acrobat Pro optimized the files and produced a file of size 6 MB. If you know how to have a similar result with open source tools, let me know.
Update (20110305):
It seems FCM comes out with a similar idea: http://fullcirclemagazine.org/python-special-edition-1/. They collected the first 8 parts of the already published Python tutorials in a special edition.
Update (20110329):
I pushed this project to GitHub, see https://github.com/jabbalaci/Full-Circle-Magazine-Series. I added some changes but I won’t rewrite this post each time. For the latest version, please refer to GitHub.
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