telotortium / bash-state

Save and restore Bash shell state for speedy startup

Bash State

A Bash library to save and restore as much local Bash state as feasible, to enable quickly starting interactive shells.

Demo

To save state of current shell, run the following at the Bash command prompt:

source bash-dump-state >/tmp/bash-state

To restore state into another shell, run the following:

source /tmp/bash-state

Installation

In your ~/.bashrc, put something like this at the beginning:

# If not running interactively, don't do anything
[ -z "${PS1:-}" ] && return

BASH_LOAD_STATE=${BASH_LOAD_STATE:-1}
BASH_STATE_FILE=${BASH_STATE_FILE:-"/tmp/bash-load-state-${USER}-${EUID}"}
if [[ "${BASH_LOAD_STATE:-0}" -ne 0 ]] && [[ -r "${BASH_STATE_FILE}" ]]; then
    if [[ -O "${BASH_STATE_FILE}" ]]; then
        echo "${HOME}/.bashrc: loading from ${BASH_STATE_FILE}. If you need to reinitialize that file, run \`BASH_LOAD_STATE=0 bash -l\`" 1>&2
        # shellcheck disable=SC1090
        source "$BASH_STATE_FILE"
        return
    else
        echo "${HOME}/.bashrc: ${BASH_STATE_FILE} exists but is not owned by you. Will try to write to it at the end of this script, but will probably fail. You should investigate." 1>&2
    fi
fi
echo "${HOME}/.bashrc: loading full Bashrc. Will run \`source ~/bin/bash-dump-state >\"${BASH_STATE_FILE}\"\` afterward." 1>&2

And something like this at the end:

echo "${HOME}/.bashrc: Running \`source ~/bin/bash-dump-state >\"${BASH_STATE_FILE}\"\` to save state." 1>&2
mkdir -p "${BASH_STATE_FILE%/*}"
# shellcheck disable=SC1090,SC1091
source ~/bin/bash-dump-state >"${BASH_STATE_FILE}"

Now all Bash shell state will be saved into ${BASH_STATE_FILE} if it doesn't exist. This file will be used to quickly load the state upon subsequent shells, unless the environment variable BASH_LOAD_STATE is unset, empty, or 0.

TODO

• Convert to bash_state_save and bash_state_load shell functions.
• Lock in bash_state_save to avoid having multiple shells stomp on each other during startup (flock on Linux and where present, shlock as fallback).
• Make compatible with Bash 3.x if possible (right now requires at least Bash 4.4 for ${x@Q} syntax).
• Convert beginning and end blocks in ~/.bashrc to shell functions.