Search through bash history shared by multiple terminal windows, but keep sessions separate

Question

I've read the solutions at Preserve bash history in multiple terminal windows and I'm looking for the following compromise:

1. Commands from all concurrent bash sessions are appended after being executed to one shared file
2. Ctrl+r in one session finds commands from other sessions
3. Pressing Up/Down in one session only cycles through the commands in that session.

Is this possible with bash? If not, with zsh maybe?

Answer 1

I've stumbled upon this question while trying to achieve something similar. I believe the following solves your problem:

1. Use a file to record all executed commands. Thanks to Eli Bendersky for his post, I use his code as it is, the only change is setting the filename in $PERSISTENT_HISTORY_FILE.

2. Install fzf with key bindings (I'm unsure if installation via package manager sets key bindings, but via git and install script does).

3. Change __fzf_history function in fzf/shell/key-bindings.bash to:

__fzf_history__() {
  local output opts script
  opts="--height ${FZF_TMUX_HEIGHT:-40%} --bind=ctrl-z:ignore ${FZF_DEFAULT_OPTS-} -n2..,.. --scheme=history --bind=ctrl-r:toggle-sort ${FZF_CTRL_R_OPTS-} +m --read0"
  script='BEGIN { $/ = "\n"; $HISTCOUNT = $ENV{last_hist} + 1 } s/^[ *]//; print $HISTCOUNT - $. . "\t$_" if !$seen{$_}++'
  output=$(
    tac $PERSISTENT_HISTORY_FILE |
        last_hist=$(HISTTIMEFORMAT='%F %T  ' builtin history 1) perl -n -l0 -e "$script" |
      FZF_DEFAULT_OPTS="$opts" $(__fzfcmd) --query "$READLINE_LINE"
    ) || return
  READLINE_LINE=${output#*| }
  if [[ -z "$READLINE_POINT" ]]; then
    echo "$READLINE_LINE"
  else
    READLINE_POINT=0x7fffffff
  fi
}

Obviously, you can make your own function stripping the code above from fzf specifics and binding it to ctrl+r.