Category: linux

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Checking varnish configuration syntax

If you’ve updated your varnish server’s configuration, there doesn’t seem to be an equivalent of ‘apachectl configtest’ for it, but you can do :

varnishd -C -f /etc/varnish/default.vcl

If everything is correct, varnish will then dump out the generated configuration. Otherwise you’ll get an error message pointing you to a specific line number.

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yum changelog (Want to know what you’re about to upgrade on CentOS/RHEL?)

Want to see what changes you’re about to apply when doing a ‘yum update’ ? Similar-ish to how ‘apt-listchanges’ works…

On CentOS 5.6, try :

  • yum install yum-changelog python-dateutil

Note, python-dateutil seems to be an unmarked dependency – i.e. you get an error message like : “Dateutil module not available, so can’t parse dates” when trying to run ‘yum changelog all updates’.

Note, /etc/yum/pluginconf.d/changelog.conf (but this didn’t seem to need changing to me).

Now you can do :

  • yum changelog all updates
  • yum changelog all mysql-server (or whatever package you’re interested in).

 

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Useful settings for history recording in bash (/etc/profile or ~/.bashrc)

shopt -s histappend
shopt -s checkwinsize
export HISTCONTROL=ignoredups:ignorespace
export HISTTIMEFORMAT='%Y-%m-%d %H:%M:%S  '
export EDITOR=vim

histappend: don’t overwrite .bash_history files on each logout; then when someone logs into the server, and messes something up, there’s a vague chance you’ll see what they did. Your history file will obviously grow to be quite big – but suppression of duplicates helps. Mine’s only 900kb after 7 months.

checkwinsize: check the window size after each command, might help some braindead programs cope with you resizing their windows, I guess.

HISTCONTROL: suppress duplicates, ignore spaces

HISTTIMEFORMAT: record a timestamp against each history entry; run ‘history’ to see an example of it’s output…

EDITOR: why would you not use vim?