Where is my PS1 defined?

Project:Linux software
Component:Documentation
Category:support request
Priority:normal
Assigned:Unassigned
Status:active
Related pages:#5663: bash prompt
Tags:bash, bash prompt, chroot
Description

When I chroot into my gentoo environment, PS1 is defined but I don't know where.

$ sudo chroot /mnt/gentoo
# echo $PS1
\[\033]0;\u@\h:\w\007\]\[\033[01;31m\]\h\[\033[01;34m\] \W \$\[\033[00m\]
/ # env-update && source /etc/profile
>>> Regenerating /etc/ld.so.cache...
# echo $PS1
\[\033]0;\u@\h:\w\007\]\[\033[01;31m\]\h\[\033[01;34m\] \W \$\[\033[00m\]

I greped but couldn't find where that PS1 was defined...