I make heavy use of Ctrl + R in my terminal, it allows me to quickly search for previously run commands. By default, the history of a Bash terminal is only written to disk, and therefore searchable in other terminals when the terminal closes. It also overwrites the whole history file. This is annoying as I usually have many terminals open, and they all get closed at different times.

This can be fixed with two additions to the .bashrc file:

shopt -s histappend
PROMPT_COMMAND="history -a;$PROMPT_COMMAND"

The first of these lines instructs Bash to append to the history file rather than overwriting it. The second causes the history to be updated each time a command completes.

At first, I thought that only the second line would be required because that seems to do everything that's required, each time a command is run it's written to the history file. The problem is that when the terminal exits, it will try to overwrite the history file with any unwritten history but there is none, so the history file is overwritten with nothing AKA it's truncated.

Infinite History

On Ubuntu the default history length is 2000 lines. I think there is very little reason not to keep everything. I also opt to ignore repeated commands and any which start with a space:

HISTFILESIZE=
HISTSIZE=
HISTCONTROL=ignoreboth