The file to edit is .bash_profile and .bashrc.   Login takes the values from the /etc/passwd file and the MAIL variable uses the path /var/mail/spool/username, where username is the name passed to login by getty.

to view the current environmental variables set by default or was set rather use the following commands:

  $ env 

  $ printenv 

to locate a particular command set or service physically in the file system use the following for example we are looking for ifconfig :

  $ whereis ifconfig 

  edit the file .bash_profile and look for the lines : PATH=$PATH:$HOME/bin 

  put your path or the path desired  ex.:  PATH=$PATH:/sbin:$HOME/bin 

  save this file and then apply the changes via the following command:

  $ source .bash_profile 

Change the Default Prompt

try the following to change the default prompt for your bash.

  $ PS1='$OSTYPE r00lz ->'

after your press ENTER, you'll see

  linux-gnu r00lz ->