#!/usr/bin/env sh
# compat: +ash +bash +dash +zsh

baknow() { ### @- backup files by appending their timestamps given by [`now`.](#now)
    ### ```
    ### $ touch -d '2001-12-25 16:30:00' butts
    ### $ baknow butts
    ### $ baknow butts
    ### cp: overwrite 'butts.2001-12-26_01800000.bak'? n
    ### $ ls -l
    ### total 0
    ### -rw-r--r-- 1 notwa None 0 Dec 25  2001 butts
    ### -rw-r--r-- 1 notwa None 0 Dec 25  2001 butts.2001-12-26_01800000.bak
    ### ```
    argc $# -ge 1 "$0" || return
    local ret=0 f=
    for f; do
        cp -ip "$f" "$f.$(now "$f").bak" || ret=1
    done
    return $ret
}

[ -n "${preload+-}" ] || . ~/sh/preload || exit 2
eval ${preload:-preload} argc now
[ -n "${preload+-}" ] || baknow "$@"