Preserve bash history

 # Maximum number of history lines in memory

export HISTSIZE=50000

# Maximum number of history lines on disk

export HISTFILESIZE=50000

 
# Ignore duplicate lines

export HISTCONTROL=ignoredups:erasedups

# When the shell exits, append to the history file instead of overwriting it

shopt -s histappend

# After each command, append to the history file and reread it

export PROMPT_COMMAND="${PROMPT_COMMAND:+$PROMPT_COMMAND$'n'}history -a; history -c; history -r"

 

 

# Linux command history with date and time.

echo 'export HISTTIMEFORMAT="%d/%m/%y %T "' >> ~/.bash_profile

source ~/.bash_profile

Or set it permenant, add below entry into .bashrc

export HISTTIMEFORMAT="%d/%m/%y %T "