4.14 Changing the Pyramid Router’s Hostname - BrainDump

Problem

Pyramid is a nice name, but you really want to change it to something else. You tried editing /etc/hostname, but the name reset to Pyramid after reboot. Arg! How do you make it what you want?

Solution

The files listed in /etc/rw/ are mounted in a temporary writeable filesystem, and are copied from /etc/ro at boot. /etc/hostname is symlinked to /rw/etc/hostname:

  pyramid:~# ls -l /etc/hostname
  lrwxrwxrwx  1 root root 18 Oct 30 2006 /etc/hostname -> ../rw/etc/hostname

So, you can make /etc/hostname immutable (remove the symlink to /rw/etc/hostname), or edit /ro/etc/hostname.

Discussion

The filesystem is set up this way to reduce writes, because Compact Flash supports a limited number of writes.

You can use find to see which files in /etc are symlinks:

  pyramid:~# find /etc -maxdepth 1 -type l -ls

6051 0 lrwxrwxrwx 1 root	root	14 Oct 4	2006 /etc/mtab -> ../proc/
mounts
6052 0 lrwxrwxrwx 1 root	root	21 Oct 4	2006 /etc/resolv.conf -> ../
rw/etc/resolv.conf
6079 0 lrwxrwxrwx 1 root	root	30 Dec 31	2006 /etc/localtime -> /usr/
share/zoneinfo/US/Pacific
6081 0 lrwxrwxrwx 1 root	root	18 Oct 4	2006 /etc/hostname -> ../rw/
etc/hostname
6156 0 lrwxrwxrwx 1 root	root	15 Oct 4	2006 /etc/issue -> ../rw/
etc/issue
6195 0 lrwxrwxrwx 1 root	root	17 Oct 4	2006 /etc/zebra -> ../usr/
local/etc/
6227 0 lrwxrwxrwx 1 root	root	16 Oct 4	2006 /etc/resolv -> ../rw/
etc/resolv
6426 0 lrwxrwxrwx 1 root	root	19 Oct 4	2006 /etc/issue.net -> ../
rw/etc/issue.net
6427 0 lrwxrwxrwx 1 root	root	17 Oct 4	2006 /etc/adjtime -> ../rw/
etc/adjtime

See Also

1. man 1 find
   
2. man 1 ls

Please check back for the conclusion to this series.