Tipps and Tricks by Thomas
I am an avid user of Linux and other derivatives of Unix.
I come up with few-line solutions that once in a while other people like a lot.
I put those where I believe they might be valuable for a wider audience.
Android development
I recently started to write programs for my android cell phone.
The results and maybe also some tipps and tricks are here.
Copy and pasting into Google Docs in Chrome under Linux
For a reason unknown to me, in Google Chrome, copy and pasting by clicking the middle mouse button does not work in Google Docs in Google Chrome. The reason for this is that here only the clipboard (the thing you control using C-c, C-x, and C-v) is supported. However, most applications that I use (e.g. xterm, emacs) do not properly support that but rather support the “old-school” copy and pasting under X that is triggered by highlighting and middle-clicking.
To convert one into the other, you can use xclip and this commandline:
xclip -o | xclip -selection clipboard
which puts the highlit text into the clipboard that is triggered using C-v.
For absolute convenience put this command onto a hotkey and start copy and pasting.
LaTeX-Tricks
Squeezing papers into X pages
LaTeX beamerposter
Jointly with Philippe Dreuw I created the beamerposter package
based on the beamer and the a0poster classes which allows to
create posters of arbitrary size using LaTeX which even look nice.
The rounding package
Jointly with Philippe Dreuw I created macros to allow for rounding of numbers in LaTeX documents. This is very handy, if you have a table, but you don’t yet know to what precision you want to show the numbers in the end. Just put in the full precision and decide later.
Download: style file example
more coming soon
Shell-Tricks and tools
rowavg.py and colavg.py
Two very simple tools I frequently use are rowavg.py and
colavg.py. They compute the average of columns or rows of their
stdin. I use this for example when I want to compute the average
result of a series of experiments I computed parallelized on a
cluster:
grep '^ERROR RATE' *.log | colavg.py
joinlines.py and joinprefixlines.py
Imagine you have multiple results per file, e.g. cross-validation, and you want to have the average (see above) for them individually.
Therefore I use joinprefixlines.py:
grep '^ERROR RATE' *.log | joinprefixlines.py -d : | colavg.py
will get all lines starting with ERROR RATE from all log-files,
will then concatenate all lines from one fill and average over the
columns.
joinlines.py <n> reads stdin and concatenates every n lines.
Download: joinlines.py joinprefixlines.py
todeadline.sh
Ever wondered how long you really have until the deadline of a conference? Luckily, bash has all the tools onboard to figure out… including time zone conversion. Just change the DEADLINE variable to your deadline and run the script.
Download: todeadline.sh
tablify.py
One of my most usefull python scripts is tablify.py which I use to create tables out of raw data. I use this a lot to summarize the results of a series of experiments.
Say I have my results in a set of files and using a series of grep, awk, sed,
# grep ^EER *.out | grep -v svm | awk '{print $1,$2,$4}' | sed -e 's/semCon-//' -e 's/\.[0-9]*\.0\.out:EER:/ /' | tr - ' ' | > RESULTS.txt
I format them into a format like this:
# cat RESULTS.txt
m0 b1.1 0.660566 0.723227
m0 b1.2 0.665577 0.731097
m0 b1.5 0.672113 0.740922
m0 b2.0 0.671024 0.744400
m1 b1.1 0.660566 0.723227
m1 b1.2 0.665577 0.731097
m1 b1.5 0.672113 0.740922
m1 b2.0 0.671024 0.744400
m2 b1.1 0.660566 0.723227
m2 b1.2 0.665577 0.731097
m2 b1.5 0.670153 0.740704
m2 b2.0 0.672767 0.744604
where m and b are parameters to my algorithm which I want to analyse, and the other two columns are two different evaluation measures.
Then, I call
# cat RESULTS.txt | tablify -n 2 -avg
| b1.1 b1.2 b1.5 b2.0
---+----------------------------------------------------------------------------
m0 | 0.660566 0.723227 0.665577 0.731097 0.672113 0.740922 0.671024 0.744400 0.6673 0.7349
m1 | 0.660566 0.723227 0.665577 0.731097 0.672113 0.740922 0.671024 0.744400 0.6673 0.7349
m2 | 0.660566 0.723227 0.665577 0.731097 0.670153 0.740704 0.672767 0.744604 0.6673 0.7349
AV | 0.6606 0.7232 0.6656 0.7311 0.6715 0.7408 0.6716 0.7445
and this table very easily shows that the m-parameter has no impact and the b parameter has an impact.
The last row/columns are the average values of their respective columns/rows.
Tablify can work with arbitrary many dimensions for both input and output variables. However, it becomes hard to read tables with more than 3 or 4 input variables.
Download: tablify.py
Get a 32-bit binary work on a 64-bit linux machine with missing libraries (presta edition)
Say you have a program that was compiled for a 32-bit x86 linux distribution. Now you want to use it on your new and nice 64-bit x86-64 machine but you do not want (or can) to install all 32 libraries to this system. How do you do it.
- you find a 32-bit machine on which it works
- you go to the directory where you have that program
- you create a new directory lib32-yourprogram
- you run ldd ./yourprogram which will tell you which libraries it needs
- you copy all the libraries into the new directory lib32-yourprogram (if the formatting of ldd is right, you can do this using for i in
ldd ./yourprogram | grep '=>' | awk '{print $3}'; do cp $i lib32-yourprogram ; done) -
you create a shell script called yourprogram.sh which contains (and of course replace CURRENTPATH with the actual path where you did all this)
#!/bin/bash export LD_LIBRARY_PATH=CURRENTPATH/lib32-yourprogram CURRENTPATH/yourprogram ${*} - now you run yourprogram.sh instead of yourprogram and everything should be fine
### Get sound from a video
Once in a while, I find a video online from which I would love to have the sound as an mp3 file to put on my mp3 player.
To do so, use ffmpeg ffmpeg -i VIDEOFILE outfile.mp3
and enjoy the mp3.