If you need to see Bash history with timestamps, use this command.
HISTTIMEFORMAT="%d/%m/%y %T "
To make it permanent, add it to your .bashrc.
echo 'HISTTIMEFORMAT="%d/%m/%y %T "' >> ~/.bashrc
Timestamps accuracy is retroactively, meaning it will not be accurate for commands performed prior to the history time format being set.
.bash_profile is executed for login shells. .bashrc is executed for interactive non-login shells. When you login, .bash_profile is executed. If you are already logged in, .bashrc is executed. .bashrc is also executed when you start a new bash using /bin/bash.
How to set up umask for a Linux user.
# sets umask for all users
# sets umask for a user
Add the following umask line to the file.