func to use in bash to log invocations of `defaults write`

log_defaults_writes.bash

# to be run as your `PROMPT_COMMAND`, this will log any invocations of `defaults write`
# now you stand a chance of figuring out which time when you pasted something from a
# random website into your terminal months ago is now totally screwing up your mac
function __log_defaults_writes {
    local DEFAULTS_WRITES_HISTORY="$HOME/.defaults_writes"

    if history 1 | grep -F -q 'defaults write'
    then
        chmod u+w "$HOME/.defaults_writes" # make log file writeable
        echo -en "$(date +%Y%m%d.%T):\t"$'\t' >> "$DEFAULTS_WRITES_HISTORY" # add timestamp
        history 1 | perl -pe 's/^\s*\d*\s*//' >> "$DEFAULTS_WRITES_HISTORY" # strip history number preamble

        # prevent accidental deletion/truncation of the log file and
        # make sure log file is readable only by user, in case sensitive data leaks into it
        chmod 400 "$HOME/.defaults_writes"
    fi
}