Why can't combine the two configuration file --/home/normal/.bashrc and /root/.bashrc-- into just one file?

Question

Os : debian8. There are two users :normal and root.

touch /var/log/all.log
chmod  777  /var/log/all.log

For normal.

vim  /home/normal/.bashrc
export HISTTIMEFORMAT="%Y-%m-%d:%H-%M-%S:  `whoami` : "    
export PROMPT_COMMAND='history  > /var/log/all.log'

source /home/normal/.bashrc

All the history command for normal(the user) will write into /var/log/all.log.

For root the same way.

vim  /root/.bashrc
export HISTTIMEFORMAT="%Y-%m-%d:%H-%M-%S:  `whoami` : "    
export PROMPT_COMMAND='history  > /var/log/all.log'

source /root/.bashrc

All the history command for root(the user) will write into /var/log/all.log.

Now i want to combine the two configuration file into one file.
Delete the two lines in both /home/normal/.bashrc and /root/.bashrc .
1. Combine them into /etc/profile.

vim  /etc/profile    
export HISTTIMEFORMAT="%Y-%m-%d:%H-%M-%S:  `whoami` : "    
export PROMPT_COMMAND='history  > /var/log/all.log'    

source /etc/profile

All the history info for normal can't be written into /var/log/all.log.
All the history info for root can be written into /var/log/all.log.
2. Combine them into /etc/bash.bashrc .

vim  /etc/bash.bashrc     
export HISTTIMEFORMAT="%Y-%m-%d:%H-%M-%S:  `whoami` : "    
export PROMPT_COMMAND='history  > /var/log/all.log'

source /etc/bash.bashrc

All the history info for normal can't be written into /var/log/all.log.
All the history info for root can be written into /var/log/all.log.

Why can't combine the two configuration file --/home/normal/.bashrc and /root/.bashrc-- into just one file?

Answer 1

What you're looking for is $HISTFILE, and you get that information from man bash:

HISTFILE ---- The name of the file in which command history is saved (see HISTORY below). The default value is ~/.bash_history. If unset, the command history is not saved when a shell exits.

So, set $HISTFILE to /var/log/all.log in your profile and that should do it.

export HISTFILE=/var/log/all.log