Syntax highlight in vim

Although not being addicted to vim I do happen to use it on a regular basis as it is available on virtually all environments I do meaningful work with :). To get it a bit fancier you can add the following to your ~/.vimrc.

vim python coloring

syntax enable
set background=dark
colorscheme solarized 
set tabstop=4 
set shiftwidth=4 
set expandtab

Download and copy corresponding theme like solarized.vim to ~/.vim/colors

:wq

Small update
If you get annoying A/B/C/D characters when pressing arrow buttons either change .vimrc to get 

set nocp

or type it in the vim prompt

:set nocp

Enjoy!

Upgrade Ubuntu server with boot partition full

At certain point my small silent server needed an extra package, but running apt-get only gave me errors. Digging further I found that my /boot partition (default Ubuntu server setup) was running out of disk space. After manually deleting old versions of images I finally got space, but that didn’t fix broken packages, e.g.:

$ sudo apt-get -f install
dpkg: dependency problems prevent configuration of linux-server:
linux-server depends on linux-image-server (= 3.2.0.53.63); however:
Version of linux-image-server on system is 3.2.0.58.69.
linux-server depends on linux-headers-server (= 3.2.0.53.63); however:
Version of linux-headers-server on system is 3.2.0.58.69.
dpkg: error processing linux-server (--configure):
dependency problems - leaving unconfigured
No apport report written because the error message indicates its a followup error from a previous failure.
Errors were encountered while processing:
linux-server
E: Sub-process /usr/bin/dpkg returned an error code (1)

The only fix I have found was downloading and installing the missing package manually:

$ wget https://launchpad.net/ubuntu/+archive/primary/+files/linux-server_3.2.0.58.69_amd64.deb
$ sudo dpkg -i linux-server_3.2.0.58.69_amd64.deb

Enjoy!

C++11 vs Python – not quite there yet

Although not exactly fair, while reading the C++ Primer book to refresh my C++11 knowledge during Christmas break (OK, after kids went asleep), I came across the example given for the new C++11 features (lambdas), strings and STL usage in chapter 16, which does nothing more than counting words in a text file. This is a rather classical example and I happen to have it as a part of the Python course I give to my colleagues. Of course I couldn’t hold myself from comparing C++11 and Python as C++11 actually tries to get higher level and closer to languages like Python. Here is what I’ve got.
Continue reading “C++11 vs Python – not quite there yet”

Scan and create multipage .pdf files from .jpeg

Recently I needed to scan and mail multi-page documents. I have a rather simple scanner that can produce descent .jpeg files, but when combining into a document it sucks. Therefore I prefer to scan in 100% quality and then produce documents depending on my needs.

E.g. hereby some commands to put two scanned pages into a single .pdf document with 75% quality (reducing ~2.3MB images into ~800KB):


convert -quality 75 page_1.jpeg page_1_75.jpeg
convert -quality 75 page_2.jpeg page_2_75.jpeg
convert -page A4 -compress jpeg page_1_75.jpeg page_2_75.jpeg document.pdf

One-liner to rename files in bash

To rename many files from one pattern to another use e.g.

for i in *.jpeg; do mv $i ${i//exampel/example}; done

Some useful patterns:

${parameter//substring/replacement}
${parameter##remove_matching_prefix}
${parameter%%remove_matching_suffix}
${parameter:offset}
${parameter:offset:length}
${parameter:offset:length}

To check whether the parameter is null:

${parameter:+use this if param is NOT null}
${parameter:-use this if param is null}
${parameter:=use this and assign to param if param is null}
${parameter:?show this error if param is null}