Setup passphraseless ssh for Hadoop in Fedora 10

To run Hadoop it is necessary (at least that is what I know) to be able to ssh to the localhost without a passphrase. The Hadoop quick start guide has simple instructions on how to do that. The first time I installed and ran Hadoop was for a class project and I worked in a pc having Ubuntu 8.04. I could follow all the instructions of that guide without any problem. But this time when I wanted to run it on my laptop having Fedora 10, the passphraseless ssh was not working. I searched the internet for a solution and I found an excellent one here, thanks to Daniel Owen for the article. The trick is in the permissions. The authorized_keys file must have the permission 644. Anything other than that does not work. The known_host file created by ssh client also has the same permission.

Installing TrueType fonts in Fedora 10

I wanted to install four Bangla fonts to read some Bangladeshi newspapers. I searched the net for instructions on how to do it and found quite a few relevant results. But all of them used some commands which I could not find in my system even with full pathnames. They simply do not exist in my Fedora box. Then I just tried the following:

1. Opened a shell and changed to super user:
# su
Password: myrootpassword
2.. Created a new directory "banglafonts" in /usr/share/fonts:
# mkdir /usr/share/fonts/banglafonts
3. Changed directory to that one:
# cd /usr/share/fonts/banglafonts
4. Copied the ttf fonts to that directory
# cp /path/to/directory/having/downloaded/fonts/*.ttf .
5. Created fonts.dir:
# mkfontdir
6. Rebuilt the fonts cache
# fc-cache
7. Exited the shell
# exit
8. Restarted Firefox.

There may be some GUI tools to ease the process but my system do not have them and I also do not want to install something which will be rarely used. The simple steps described above are easy enough, even for a newbie, to install ttf fonts in a Fedora box.

Adding mp3 Support to Fedora 10

As mp3 support is not built-in in any Linux distributions, I was looking for some way to add it to my newly installed Fedora 10. I found some working instructions here: http://www.ghacks.net/2008/12/25/add-mp3-support-in-fedora-10. There is one typo in the second command, it should be "rpmfusion-nonfree" instead of "rmpfusion-nonfree".