If you are trying to find a program, log into the shell.
Type the command:
# whereis <program>
where program is the program you are looking for, will show you one or more possibilities for what you are looking for.
If you have more than one copy of a program, say one in /usr/bin and another in /usr/local/bin/ ,
typing "which program" will show you which one will be called first.
If you can't find it at all, type command:
# locate <program>
will show you everyfile that matches "program".
Some of the most common programs :
/usr/sbin/sendmail
/usr/bin/perl
/bin/mail
/usr/bin/php
Default locations for most commonly used configuration files and important directories:
Exim
/etc/exim.conf
/var/log/exim_mainlog
/var/log/exim_rejectlog
/etc/valiases/
/etc/vfilters/
/home/username/.forward
MySQL
/root/.my.cnf
/etc/my.cnf
/var/lib/mysql/
Apache
/usr/local/apache/conf/httpd.conf
/usr/local/apache/domlogs/
System
/var/log/messages
/var/log/dmesg
Proftpd
/etc/proftpd.conf
/var/log/xferlog
/etc/proftpd/
sshd
/etc/ssh/sshd_config
