Wednesday, December 30, 2009

local usefull databases

By default, linux and unix systems have two usefull databases installed. Those databases may speed up your work as a system administrator.

First of all, there is the locate database. This database contains the list of the files in your system. Imagine you need to edit a file whose name is "password" but you can't remember its path. A quick way to do it would be :
luangsay@ramiro:/tmp$ locate -r password$
(-r switch is for using regular expressions).
To initialize the database or update it, you can use the command updatedb. Normally, your operating system does it with a cron task.

The second database is apropos, a french word which means "about". This is a collection of the first description sentences (the whatis sentence) of all the man pages. To know all the manpages that deal with the configuration of passwords, you would type :
luangsay@ramiro:/tmp$ apropos -s 5 password
login.defs (5) - configuration de la suite des mots de passe cach├ęs shadow password
passwd (5) - the password file
shadow (5) - encrypted password file
smbpasswd (5) - The Samba encrypted password file
Here, to create/update the database, you will use makewhatis (or mandb in Debian).

Another interesting database that is less known is perlindex. Quite usefull because perl is (still...) used by many system admins. This tool indexes all your perl modules documentation pages. So, to find all the modules installed on your system that deal with LDAP, you can type:
luangsay@ramiro:/tmp$ perlindex ldap
1 1.791 share/perl5/URI/
2 0.317 share/perl5/
3 0.137 share/perl/5.10.0/pod/perlhpux.pod
Highest mark (1.791) gives you the most relevant page. If you pulse 1, you'll get the perldoc page printed. Of course, such database isn't as big as the CPAN one, but it proved to have helped me quite a few times in the past.

Finally, I would like to say a word about maybe my prefered database. I mean, the debian packages database. Debian apt-get system is a lot more faster than redhat yum software and it offers you many more packages. I believe every debian admin knows the power of the "apt-cache search/show" commands so I won't waste my time giving an example. For those who don't have a debian based distribution, you can get an idea of this database on this web page. If you have to install a new solution on your servers, and you don't know what software can handle it, the debian package can give you a precious help to get the information. Even if you don't have debian, it can be very usefull.

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