per-directory-bash-history.md

Per-directory Bash history (w/o aliasing cd)

I use Bash’s PROMPT_COMMAND variable:

The value of the variable PROMPT_COMMAND is examined just before Bash prints each primary prompt. If PROMPT_COMMAND is set and has a non-null value, then the value is executed just as if it had been typed on the command line.

The source code should be pretty straight forward, but if not, please ask in the comments. Put this in your .bashrc or similar:

# per-directory Bash history
function check_for_local_history {
  local last_command=`history 1`
  local last_command=${last_command:27} # this depends on HISTTIMEFORMAT

  function main {
    if changing_directory; then
      if found_local_history_file; then
        use_history_file $PWD/.bash_history
      else
        use_history_file ~/.bash_history
      fi
    fi
  }

  function changing_directory {
    is_cd_nothing || is_cd_something || is_a_cd_alias
  }

  function is_cd_nothing {
    [ ${#last_command} -eq 2 -a "${last_command:0:2}" = "cd" ]
  }

  function is_cd_something {
    [ ${#last_command} -gt 2 -a "${last_command:0:3}" = "cd " ]
  }

  function is_a_cd_alias {
    local cd_aliases=`alias | grep "='cd " | grep -P -o '[a-z]+(?==)'`
    echo $cd_aliases | grep -q "\<$last_command\>"
  }

  function found_local_history_file {
    [ -e .bash_history ]
  }

  function use_history_file {
    history -w
    history -c
    export HISTFILE=$1
    history -r
  }

  main
}

PROMPT_COMMAND="check_for_local_history"