Wrangling bash_history across multiple sesions

BASH_HISTORY_FILE or HISTFILE

I find myself constantly using multiple terminals on the same system. The default bash history is a good start, but not enough for my needs. After endless searching, testing, ignoring, deleting, and procrastinating I finally found a solution that works for me.

Session Isolation
- I don’t need new history items available across sessions
- Typically the work I am preforming is isolated but similar enough that having commands updated between sessions is both obnoxious and unhelpful.
Custom Timestamp
- I like seeing a particular timestamp format in my history output (helps me remember what I was doing at that time)
Dedupe
- Like I mentioned above, I don’t need commands shared across terminal windows
- Also, I don’t like duplicate uses of command in my history
- Sure I may lose the first, or prior, occurrence(s) of a command. But I only require the last use.
Write on session exit
- I don’t want to lose my history to a kill -i <shell_pid>
- I also don’t want to lose my history if I close the wrong session tab
- dedupe only needs to happen at this point
Use only linux bash commands
- I don’t want to download some fancy utility.
- use the fewest number of commands
Unlimited history
- computers are big enough and fast enough to handle this
- new versions of bash allow an unlimited history

`~/.bashrc`

HISTCONTROL=ignorespace:ignoredups:erasedups
shopt -s histappend
HISTSIZE=-1
HISTFILESIZE=-1
HISTTIMEFORMAT="[%b %d,%Y %T] "
PROMPT_COMMAND="history -a;${PROMPT_COMMAND}"

`/etc/profile.d/00-dedup-bash-history-on-exit.sh`

function deduphistory {
  echo "deduphistory"
  history -w ~/.bash_history.dedup_backup
  history -n; history -a
  tac ~/.bash_history | awk '!x[$0]++' | tac > ~/.bash_history_new_dedup
  history -cr ~/.bash_history_new_dedup
  history -w
}
# cleanup bash history on exit
trap deduphistory EXIT

Profit

Watch your history get appended and deduped on exit. No more lost history (mostly) And be happy

Files available as gists

https://gist.github.com/therevoman/a7532af575479f0a2b5edfbb0bef8212

Originally posted on GitHub: https://github.com/therevoman/nate-revo-blog/issues/2