Never lost your bash history again

I had a cronjob which was archiving my bash history file, but after one of my Fedora upgrades, it stopped working and I lost my .bash_history. Now, that’s unfortunate!

To prevent this in the future, I have decided to take different approach. I have a script now which I run from my bash profile. It creates backups every month (leaving last 200 commands there so I will not lost the latest commands). Since I have this in my profile, it will work forever.

The script is lightweight and basically it only adds one extra check - if backup is older than latest bash history file, copy it over. So this should not slow down my bash startup at all (basically one cp command a day when I start my laptop or when I append a history in a terminal).

Here it is:

#!/bin/sh
# This script creates monthly backups of the bash history file. Make sure you have
# HISTSIZE set to large number (more than number of commands you can type in every
# month). It keeps last 200 commands when it "rotates" history file every month.
# Typical usage in a bash profile:
#
# HISTSIZE=90000
# source ~/bin/history-backup
#
# And to search whole history use:
# grep xyz -h --color ~/.bash_history.*
#

KEEP=200
BASH_HIST=~/.bash_history
BACKUP=$BASH_HIST.$(date +%y%m)

if [ -s "$BASH_HIST" -a "$BASH_HIST" -nt "$BACKUP" ]; then
  # history file is newer then backup
  if [[ -f $BACKUP ]]; then
    # there is already a backup
    cp -f $BASH_HIST $BACKUP
  else
    # create new backup, leave last few commands and reinitialize
    mv -f $BASH_HIST $BACKUP
    tail -n$KEEP $BACKUP > $BASH_HIST
    history -r
  fi
fi