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Wed, 11 Jun 2008

Per-user resolv.conf files

I want per-user resolv.conf files. I've mentioned this in a couple of places and got asked why. It's so that I can have a consistent set of aliases everywhere I go (so I can, eg, type ssh sdf instead of ssh sverige.freeshell.org) and also so that the resolver will fill in my choice of domain on the end of hostnames, so I can be lazy and type ssh plough instead of ssh plough.barnyard.co.uk.

Some quick googling didn't turn up anything usefully cross-platform, but the implementation shouldn't be too hard - just set LD_LIBRARY_PATH or LD_PRELOAD and provide my own resolver library. Unfortunately, the resolver is part of libc so I need to figure out how to:

  • persuade arbitrary binaries to load an extra library;
  • have that library effectively replace bits of libc ...
  • ... even when the functions I'm replacing are called by other functions in libc

Damn, I might have to read about how the linker actually works if I'm ever to do this.

Posted at 19:10 by David Cantrell
keywords: geeky | unix
Permalink | 5 Comments
Tue, 20 Feb 2007

The value of backups

Yesterday, my file server crashed badly. I hit the per-user process limit, so couldn't log in remotely, couldn't log in on the console - and so couldn't do a graceful shutdown. So I cycled the power. When it came back up, one of the filesystems was a bit buggered, as expected. But it was a bit more buggered than I first thought and couldn't be recovered. So I mkfsed it, adding journalling while I was at it, and it is now restoring from the last backup.

Rsnapshot FTW!

Posted at 20:12 by David Cantrell
keywords: geeky | rsnapshot | unix
Permalink | 0 Comments