Coredump

Hmmm…

In Bash, I would have done:

$ for i in `seq 100` ; do if [ `expr $i % 15` -eq 0 ] ; then echo FizzBuzz; elif [ `expr $i % 3` -eq 0 ]; then echo Fizz; elif [ `expr $i % 5` -eq 0 ]; then echo Buzz; else echo $i; fi; done

Then again, it took me about 10 minutes to do that. (I couldn’t get the ternary operator to work, somehow.) In C: about five minutes (rusty — I last used C way back in college {ages ago!}).

In a recent phone interview, I was asked to programmatically (in shell) rename a set of files. I blundered for about two minutes, and gave up in the end, saying I could probably do that by experimentation. I could fairly say I passed that interview. The point? Answering “FizzBuzz” questions does not reflect real-world situations — it’s how you approached the problem, even if you didn’t get the answer, that matters.

If I were an interviewer, I’d concentrate on the steps rather than the solution.

I’m currently playing with Devil’s Pie, a utility that matches windows and window events to a set of rules similar to Emacs’ (yikes! :P) S-expressions.

I installed Devil’s Pie on my work desktop (running FC6), thus:

$ sudo yum install devilspie

(I have previously organized my desktop with four workspaces: for browsing, remote SSH sessions, remote desktop sessions, and other tasks.) I then created a configuration file:

$ mkdir .devilspie && vi ~/.devilspie/workspaces.ds
   (debug)
   (if (is (application_name) "Firefox") (begin maximize (undecorate (set_workspace 1))))
   (if (is (application_name) "Terminal") (begin maximize (undecorate (set_workspace 2))))
   (if (matches (application_name) "^rdesktop.+") (begin center (maximize (set_workspace 3))))

and invoked Devil’s Pie: devilspie -d ~/.devilspie/workspaces.ds &. The (debug) line in the configuration is, heh, for debugging purposes so Devil’s Pie will print out events and other information, which I can then later use.

Seems pretty straightforward, though there isn’t much functionality that I can use. (Then again, my requirement is minimal: I just want to group apps to different workspaces to avoid clutter.) I can then drop Devil’s Pie in my X startup script, along with the other startup apps.

(This is part of an ongoing series on Linux CLI shortcuts and hacks.)

After editing .bashrc and .bash_profile, you can reload the values by running

$ source ~/.bash_profile

Given:

$ ll Archive/
total 8
-rw-r--r-- 1 d3m users 10 2007-01-26 16:29 file1.z
-rw-r--r-- 1 d3m users 15 2007-01-26 16:29 file2.z

What happens if:

$ cd ~/Destination; cp ~/Archive/*.z

It’s been a long time since I did a source tar-ball install. But the production servers at work require that applications that are not part of the standard install base (from Kickstart/Jumpstart and VMWare images) should be compiled from source. It was a very refreshing experience.

So after going through the usual configure; make; make install invocation, it was time to make sure that the app is persistent at boot. I would have copied an init script from my *nix desktop, but good thing SLES had a baseline script in /etc/init.d/skeleton.

In a nutshell, the steps are:

1. Define the INIT INFO section, as per the LSB specs.
2. Fill in the variables.
3. Use /etc/rc.status and rc_* functions for sanity checks.
4. Create the basic start, stop and status functions.
5. Use YAST (System > System Services (Runlevel)) — or, if available, innserv — to enable the startup script.

Below is a script I wrote for Apache:

#!/bin/sh
#
# Author: Ian Dexter R. Marquez
#
# /etc/init.d/httpd
#
### BEGIN INIT INFO
# Provides: httpd
# Required-Start: $local_fs
# Required-Stop: $local_fs
# Default-Start: 3 5
# Default-Stop: 0 1 2 6
# Description: Start the Apache httpd daemon
### END INIT INFO
 
HTTPD=/path/to/apache/2.2.4/bin/httpd
APACHECTL=/path/to/apache/2.2.4/bin/apachectl
PROG=httpd
 
test -x $HTTPD || exit 5
test -s /etc/rc.status && . /etc/rc.status && rc_reset
 
start() {
   echo -n "Starting $PROG: "
   $HTTPD -k start
   rc_status -v
}
 
stop() {
   echo -n "Stopping $PROG: "
   /sbin/killproc $HTTPD
   rc_status -v
}
 
status() {
   echo -n "Checking $PROG: pid "
   /sbin/pidofproc $HTTPD
   rc_status -v
}
 
case "$1" in
   start)
      start
      ;;
   stop)
      stop
      ;;
   restart)
      stop
      start
      rc_status
      ;;
   status)
      status
      ;;
   try-restart|condrestart)
      if test "$1" = "condrestart"; then
         echo "${attn} Use try-restart ${done}(LSB)${attn} rather than condrestart ${warn}(RH)${norm}"
      fi
      $0 status
      if test $? = 0; then
         $0 restart
      else
         rc_reset   # Not running is not a failure.
      fi
      # Remember status and be quiet
      rc_status
      ;;
   graceful|help|configtest|fullstatus)
      $APACHECTL $@
      rc_status
      ;;
   *)
      echo "Usage: $PROG {start|stop|restart|status|graceful|help|configtest|fullstatus}"
      exit 1
esac
rc_exit

References:

• Writing Init Scripts, Novell Developer Net.
• Creating Custom Init Scripts, Novell Cool Solutions.