Busser Tech Notes

A guide for various things computerish… where not otherwise specified, a lot of what is noted below is debian-based.

Command-line usage

• apt-cache
  • sudo apt-cache showpkg gnumed-client shows the versions, the depends
  • sudo apt-cache showpkg gnumed-server shows the versions, the depends
  • sudo apt-cache policy python-psycopg2 shows what is installed, available, pinning values
• apt-get
  • sudo apt-get -t testing install gnumed-client installs, on Debian, the GNUmed client
• operating system information
  • uname -a yields: Linux debian 2.6.26-2-686 #1 SMP Sun Jun 21 04:57:38 UTC 2009 i686 GNU/Linux
  • cat /etc/debian_version yields: 5.0.2
  • cat /etc/apt/sources.list shows one's sources
  • cat /etc/apt/preferences (provided the file has been created) shows any preferences including pinning as provided here
  • packages… show what's installed (using a post-install apt-show-versions)
    • sudo apt-show-versions | grep psyco (here the | grep was an optional filter among results, for "psyco...")
  • top shows running processes and, if a process has hung up the system, the kill command can release it
  • users tells you who else is logged in, before you might sudo shutdown

Date-Time troubleshooting

• Debian when run inside a VM may lose synchronization to servers (for example the enclosing host OS may go to sleep) so, as sudo
  • run ntpq -p to confirm that NTP is still working (Connection refused suggests is needs restarting)
  • run /etc/init.d/ntp restart to restart, wait a few minutes, then re-issue ntpq -p
  • guide here
• various issues with date-time formatting and localization, the devel archive has lots on this

Debian installation

• DebianGuideLong

Mac overview

• see MacPackages references which include references to Apple documentation
• outline of Mac OS processes
• listing of Mac OS X 10.5.x Applications and Their Locations
• tree command, on Mac: find . -print | sed -e 's;[^/]*/;|____;g;s;____|; |;g'

Shell command: executables

• "sh" is the name of the executable of a shell program
• doing "sh some-program.sh" is pretty much like "python gnumed.py" except that the interpreter is the shell rather than Python
• running an executable program
  • doesn't actually need the "sh" in front of it. Rather, sh is assumed by default
  • we must give an explicit path (commonly the current directory ./) without which the shell would trawl the executable directories for it (/bin/, /usr/bin/ etc).

Uscan

• uscan is a Debian tool which inspects a so called watch file for new upstream versions. It run by our debian-med maintainer against this wiki page for a string matching http://www.gnumed.de/downloads/client/[\d\.]+/GNUmed-client\.([\d\.]+)\.tgz