Arch: find package for specific command

The problem is: How do you find the package for a given command? Two solutions are presented.

  1. Use the program pkgfile.
  2. Use pacman.
    1. Update database: $ sudo pacman -Fy
    2. Searching: $ pacman -Fs $cmd



Install firefox nightly on ubuntu/mint

for the nightly builds of firefox do the following:

  1. just include the following ppa:$ sudo add-apt-repository ppa:ubuntu-mozilla-daily/ppa
  2. update and install the package, called firefox-trunk


for the firefox-next install see:

git ignore files (especially global)

one can create gitignore files for specific repos and also globally.
github offers gitignore templates for lots of different things: frameworks, languages, editors, operating systems, etc. (link: github-ignore-templates).

the templates should be copied to some file (~/.gitignore_global) and applied with this command:
git config --global core.excludesfile ~/.gitignore_global



it basics: types and number representation

types (int,long,..) often vary in size and therfore one uses standard types: qtypes_t where q is a qualifier, type is the base type, s is the width in bits and _t is an extension so you know you are using the C99 defined types (e.g., uint8_t)

negative binary number representations:

  1. sign bit: one bit is specialized as a sign bit
  2. one’s complement:
    • “not” operator applied to positive number yields neg. number
    • advantage: subtraction is easy (just add and also add additional carry over bit)
  3. two’s complement:
    • same as one’s comp. but you always add an additional one
    • advantag: subtraction is even easier (just add) and all simple math op. are now easy to manage