Category Archives: Linux

Pidgin, purple-remote, and solving the “No existing libpurple instance detected” error

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I was Googling around tonight to find an answer to a question I was asked about purple-remote and duplicate status messages in the Pidgin Instant Messaging Client and I ran across many, many people posting messages that they couldn’t get purple-remote to work. They had no problem running purple-remote from a command line, but as soon as they tried to call it from a web page or a cron job or from some other process they started seeing the “No existing libpurple instance detected” error.

The solution to this problem is the same as the solution to my original Update Pidgin IM status on Ubuntu using cron article. purple-remote communicates with Pidgin using DBUS. If you’re running purple-remote from a cron job or from some a process that is not owned by you (for instance, an Apache CGI script being run by the “apache” user) then you need to set the DBUS_SESSION_BUS_ADDRESS environment variable for that process so that it matches the DBUS_SESSION_BUS_ADDRESS environment variable for your login. Once that’s done, any processes run by that user that communicate using DBUS will use the same DBUS session that you’re using, so when the “apache” user runs purple-remote it’ll talk to the copy of Pidgin that you are running.

There are many ways you can disclose the value of your login’s DBUS_SESSION_BUS_ADDRESS value to other programs. The easiest way I’ve found is just to save the value to a file and then have your cron job or Apache CGI script execute that file as a script. Check out the Update Pidgin IM status on Ubuntu using cron article for examples of exactly how to do this.

Installing Skype on Ubuntu 9.04 using Synaptic

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Want to make free phone calls using Skype? Running Ubuntu 9.04? Want to make sure that Skype stays up-to-date with the latest security patches and updates once you install it? Here’s how:

On the Skype Download for Linux page Skype lists Ubuntu 7.04-8.04 as the only supported versions of Ubuntu. You can install Skype on Ubuntu 9.04, but when new updates or security fixes come out you won’t get an automatic update. If you want to make sure that your Skype installation stays up-to-date you should add skype.com as a valid software repository and install Skype from that. If you do this you’ll automatically get updates when they’re available.

To add skype.com as a repository:

  • Start up Synaptic Package Manager. (On Gnome go to System > Administration > Synaptic Package Manager)
  • Select Settings > Repositories
  • Click the Third-Party Software tab
  • Click Add
  • Enter “deb http://download.skype.com/linux/repos/debian/ stable non-free” as the APT line
  • Click the Reload button in the upper left-hand corner to download the list of available files from download.skype.com
  • Type “skype” in the Quick Search box and you should see Skype listed as an installable package
  • Mark it for installation and install

Skype should now appear on your Applications > Internet menu.

Update: At the time that I wrote this the instructions worked. However, it looks as if Skype has removed their apt repositories for 9.04. If you attempt to connect to http://download.skype.com/linux/repos/debian/ you’ll get a “Hi, this page is off limits” error message.

If you are running Ubuntu 10.04 or later you can get Skype directly from Canonical. See https://help.ubuntu.com/community/Skype for more info.

Upgrading Blu-ray Player Firmware from Linux

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I’ve got an older Sony Blu-ray player, a BDP-S300 model. I was trying to watch Burn After Reading tonight and the movie would not start. Not because the disc was damaged, but because it had some embedded software that didn’t work with the Blu-ray player’s old firmware — software that it used to START PLAYING THE MOVIE.

So I went to Google, typed in “Sony Blu-ray BDP-S300 firmware download” and found links to the usual suspects, Blu-ray.com and esupport.sony.com. Both sites have the latest firmware for Blu-ray players. Both have the software in an ISO CD-ROM image format, so you can burn a CD-ROM with the firmware, boot your Blu-ray player with the CD, and in 10 to 20 minutes the firmware has been upgraded. (Yes, 10-20 minutes. The firmware update process is even slower than the painfully, glacially slow disc load time for Sony Blu-ray players.)

The only problem is that both sites compress the ISO file into a Windows-based EXE file! Apparently the people at Sony don’t realize that there are people out there with Macs, so Mac users are screwed. They also don’t appear to realize that they could make the same file available as a plain ISO file and ANYONE with ANY OS with an ISO CD-burning software package and a CD-ROM burner (pretty much every personal computer made in the last 15 years) could make a CD-ROM from the file.

I have no Windows box at the moment, I do most everything on Linux, so after firing off a customer feedback letter to Sony slamming them for their short-sightedness I went ahead and clicked the pull-down menu that tells their site that yes, I was using Windows 2000, please let me download the damn file, and I downloaded UPDATE_BDPS300_VER0450.EXE.

After that it was a matter of typing:

apt-get install wine
mkdir ~/tmp/bluray
wine UPDATE_BDPS300_VER0450.EXE

A pop-up box asked me where to put the files it was about to extract from UPDATE_BDPS300_VER0450.EXE, so I clicked the Browse button and selected ~/tmp/bluray. A few seconds later UPDATE_BDPS300_VER0450.ISO was in the ~/tmp/bluray directory. I fired up K3b, clicked on the left-side file menu tree to get to ~/tmp/bluray, double-clicked the UPDATE_BDPS300_VER0450.ISO file, and burned the CD-ROM.

I stuck the CD-ROM in the Blu-ray player and about 15 minutes later the player spit the disc back out.

Now I can watch the movie…

Change your Skype availability status on Ubuntu via cron

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I used Skype when it first came out and then stopped because there were only a few other people I knew who used it regularly. Since they were all in my local calling area, if I wanted to talk to any of them for free I could just use a phone.

I just started using it again — for work — to talk with customers and consultants who do not live in the Bay Area. However, I found that my Thursday telecommute days were causing problems: Skype would be running on my work computer and people trying to call me would get ring-no-answer because I was actually at home.

Turns out you can start and stop Skype via cron the same way you can start and stop Pidgin Instant Messenger via cron, you just need to set a few environment variables and it works great.

First create the script ~/bin/export_x_info which looks like this:

#!/bin/bash
# Export the dbus session address on startup so it can be used by cron
touch $HOME/.Xdbus
chmod 600 $HOME/.Xdbus
env | grep DBUS_SESSION_BUS_ADDRESS > $HOME/.Xdbus
echo 'export DBUS_SESSION_BUS_ADDRESS' >> $HOME/.Xdbus
# Export XAUTHORITY value on startup so it can be used by cron
env | grep XAUTHORITY >> $HOME/.Xdbus
echo 'export XAUTHORITY' >> $HOME/.Xdbus

Create this script, type chmod 700 ~/bin/export_x_info so you can execute it, then execute it, then add it to System > Preferences > Sessions > Startup Programs so it will execute every time you start your computer and record the latest session address and XAUTHORITY value.

This script creates a 4-line file ~/.Xdbus with the current session address and XAUTHORITY value. By sourcing this file in the crontab file your scripts can now use dbus to send messages to X-Windows applications. To start and stop Skype at work I added these lines to my work computer’s crontab file:

# Skype on/off
00 09 * * Mon,Tue,Wed,Fri source ~/.Xdbus; /usr/bin/skype &
30 17 * * Mon,Tue,Wed,Fri killall skype

On my home computer I have:

# Skype on/off
00 09 * * Thu source ~/.Xdbus; /usr/bin/skype &
30 17 * * Thu killall skype

So on Thursdays when I telecommute Skype is running at home, the rest of the week it’s running at my office, and at night it’s turned off so customers aren’t calling me in the middle of the night.

When Skype isn’t running other users see your status as “Offline”. When cron restarts Skype it starts up with the same status it had when the process was killed. I just leave my status set to “Online,” so when cron starts Skype it shows everyone that I’m online. When cron kills the Skype process at the end of the day my status changes to “Offline” and people can’t call me.

Hope you find this useful.

Update Pidgin IM status on Ubuntu using cron

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At work we use a Jabber instant messenger (IM) server for internal company communications, so that regardless of whether someone is in the office, working from home, or on the road, they can be reached via IM.

I’m running Ubuntu both at work and at home and I use the Pidgin IM client to talk to the Jabber server. I work from home on Thursdays, and I’m always forgetting to turn Pidgin off when I leave work on Wednesday. I usually end up ssh-ing into my work box from home and killing the Pidgin client off remotely, but sometimes I forget and when I come back to work on Friday there are a half-dozen “Are you there?” -type messages on my Pidgin work-client.

So I figured I’d automate the process, automatically setting Pidgin status to “Away” and “Available” using cron, turning the work-client off entirely on Thursdays and weekends, and automatically turning the home-client on Thursday mornings and off Thursday night.

I did a little digging and found a command-line program called purple-remote that allows me to automatically update the Pidgin status and message lines. The purple-remote program is included in the libpurple-bin package, which I installed with System > Administration > Synaptic Package Manager.

Once purple-remote was installed, I fired up a terminal and did a little experimenting on the command line. I found I could set Pidigin’s status to “Away” and the status message to “At lunch” by typing:

/usr/bin/purple-remote "setstatus?status=away&message=At lunch"

I could set the status to “Available” and blank the status message by typing:

/usr/bin/purple-remote "setstatus?status=available&message="

So far so good. I can also cause Pidgin to exit with:

/usr/bin/purple-remote "quit"

Starting Pidgin is just a matter of running:

/usr/bin/pidgin

Time to set up the cron jobs. I fired up crontab -e and entered:

# IM Status
SHELL=/bin/bash
00 08 * * Mon,Fri /usr/bin/pidgin &
01 08 * * Mon,Tue,Wed,Fri /usr/bin/purple-remote "setstatus?status=away&message="
00 09 * * Mon,Tue,Wed,Fri /usr/bin/purple-remote "setstatus?status=available&message="
30 13 * * Mon,Tue,Wed,Fri /usr/bin/purple-remote "setstatus?status=away&message=At lunch"
30 14 * * Mon,Tue,Wed,Fri /usr/bin/purple-remote "setstatus?status=available&message="
30 17 * * Mon,Tue,Wed,Fri /usr/bin/purple-remote "setstatus?status=away&message="
00 19 * * Wed,Fri /usr/bin/purple-remote "quit"

This would start Pidgin at 8:00am, set my status to “Away” at 8:01am, “Available” at 9:00am, “Away – At lunch” at 1:30pm, “Available” again at 2:30pm, “Away” at 5:30pm. On Wednesday and Friday nights at 7:00pm the client shuts down entirely, on Monday and Friday mornings Pidgin gets restarted. That will leave the client off all day on Thursdays and on weekends when I’m not at the office. If my schedule changes for any reason I can still update my status in Pidgin manually.

Looks good, but this doesn’t work. Although the commands listed above work just fine on the command line, they’d fail when they were executed from cron. Checking my mail I found error messages like this:

Traceback (most recent call last):
File "/usr/bin/purple-remote", line 16, in
obj = dbus.SessionBus().get_object("im.pidgin.purple.PurpleService",
 "/im/pidgin/purple/PurpleObject")
File "/var/lib/python-support/python2.5/dbus/_dbus.py", line 218, in __new__
mainloop=mainloop)
File "/var/lib/python-support/python2.5/dbus/_dbus.py", line 107, in __new__
bus = BusConnection.__new__(subclass, bus_type, mainloop=mainloop)
File "/var/lib/python-support/python2.5/dbus/bus.py", line 121, in __new__
bus = cls._new_for_bus(address_or_type, mainloop=mainloop)
dbus.exceptions.DBusException: org.freedesktop.DBus.Error.Spawn.ExecFailed:
 dbus-launch failed to autolaunch D-Bus session: Autolaunch error:
 X11 initialization failed.

The key part of that message is “dbus-launch failed to autolaunch D-Bus session: Autolaunch error: X11 initialization failed.” dbus is a messaging system, and X11 is the implementation of X-Windows Ubuntu uses, which is what the Gnome desktop runs on. Pidgin is an application running on the Gnome desktop / X-Windows. The error message is saying that the program failed to send a message to X11 (X-Windows) and on to Pidgin.

There are three problems here:

  1. The first is that in order for purple-remote to send messages to Pidigin via DBUS it has to work it needs to know the value of the DBUS_SESSION_BUS_ADDRESS environment variable. (Kudos to explicitly ambiguous and his article at http://ubuntuforums.org/showthread.php?t=632580 for pointing me towards this solution.)
  2. In order to start Pidgin at 8:00am Pidgin needs to know the value of the of the XAUTHORITY environment variable otherwise it won’t be authorized to start up on a screen that I’m logged into.
  3. In order to start Pidgin at 8:00am Pidgin needs to know the value of the DISPLAY environment variable so it knows what screen to start up on.

When you start up Ubuntu the dbus daemon starts up and creates a unique session address. Your applications have to know this session address in order to send messages using the daemon. The address is stored in the DBUS_SESSION_BUS_ADDRESS environment variable when you log in, so if you try to run an application from the command line it gets the session address from the DBUS_SESSION_BUS_ADDRESS environment variable. Since cron runs in it’s own environment it doesn’t know the value of DBUS_SESSION_BUS_ADDRESS, so programs that depend on dbus fail when you try to run them from a cron job.

You can see the value by typing:

> env | grep DBUS_SESSION_BUS_ADDRESS
DBUS_SESSION_BUS_ADDRESS=unix:abstract=
/tmp/dbus-AmUs20000,guid=6cce82d52ca190000000000000000000

Likewise, the value of XAUTHORITY changes every time you restart your computer. You can see the current value by typing:

> env | grep  XAUTHORITY

DISPLAY remains the same between reboots. To get the value for your system, type:

> env | grep DISPLAY
DISPLAY=:0.0

Add the “DISPLAY=:0.0” line at the beginning of your crontab file and it’ll be set for Pidgin.

In order to make the environment variables available to cron jobs I created the program ~/bin/export_x_info which looks like this:

#!/bin/bash
# Export the dbus session address on startup so it can be used by cron
touch $HOME/.Xdbus
chmod 600 $HOME/.Xdbus
env | grep DBUS_SESSION_BUS_ADDRESS > $HOME/.Xdbus
echo 'export DBUS_SESSION_BUS_ADDRESS' >> $HOME/.Xdbus
# Export XAUTHORITY value on startup so it can be used by cron
env | grep XAUTHORITY >> $HOME/.Xdbus
echo 'export XAUTHORITY' >> $HOME/.Xdbus

Create this script, type chmod 700 ~/bin/export_x_info so you can execute it, then execute it, then add it to System > Preferences > Sessions > Startup Programs so it will execute every time you start your computer and record the latest session address and XAUTHORITY value.

This script creates a 4-line file ~/.Xdbus with the current session address and XAUTHORITY value. By sourcing this file in the crontab file your scripts can now use dbus to send messages to X-Windows applications. My final crontab file looks like this:

SHELL=/bin/bash
DISPLAY=:0.0
# IM Status
00 08 * * Mon,Fri source ~/.Xdbus; /usr/bin/pidgin &
01 08 * * Mon,Tue,Wed,Fri source ~/.Xdbus; /usr/bin/purple-remote "setstatus?status=away&message="
00 09 * * Mon,Tue,Wed,Fri source ~/.Xdbus; /usr/bin/purple-remote "setstatus?status=available&message="
30 13 * * Mon,Tue,Wed,Fri source ~/.Xdbus; /usr/bin/purple-remote "setstatus?status=away&message=At lunch"
30 14 * * Mon,Tue,Wed,Fri source ~/.Xdbus; /usr/bin/purple-remote "setstatus?status=available&message="
30 17 * * Mon,Tue,Wed,Fri source ~/.Xdbus; /usr/bin/purple-remote "setstatus?status=away&message="
00 19 * * Wed,Fri source ~/.Xdbus; /usr/bin/purple-remote "quit"

The call to source ~/.Xdbus on each line loads the DBUS_SESSION_BUS_ADDRESS and XAUTHORITY environment variables before executing the purple-remote command or starting Pidgin.

Now the cron works and my Pidgin status is constantly updated. The cron on my home computer is much simpler:

SHELL=/bin/bash
DISPLAY=:0.0
# IM Status
00 08 * * Thu source ~/.Xdbus; /usr/bin/pidgin &
01 08 * * Thu source ~/.Xdbus; /usr/bin/purple-remote "setstatus?status=away&message="
00 09 * * Thu source ~/.Xdbus; /usr/bin/purple-remote "setstatus?status=available&message="
30 13 * * Thu source ~/.Xdbus; /usr/bin/purple-remote "setstatus?status=away&message=At lunch"
30 14 * * Thu source ~/.Xdbus; /usr/bin/purple-remote "setstatus?status=available&message="
30 17 * * Thu source ~/.Xdbus; /usr/bin/purple-remote "setstatus?status=away&message="
00 19 * * Thu source ~/.Xdbus; /usr/bin/purple-remote "quit"

The same technique works for other X-Windows programs as well. For instance, I added this line to my cron:

30 17 * * Mon,Tue,Wed,Fri source ~/.Xdbus; /usr/bin/notify-send "Go Home" "Time to Go"

So every day at 5:30pm a “notify” message pops up reminding me that it’s time to go home.

Hope you find this useful.