Date

2015-06-17

date +"%Y-%m-%d"

23:38:43

date +"%T"

23:38

date +"%H:%M"

Дата в переменной

NOW=$(date +"%Y-%m-%d %H:%M")
echo $NOW

Пример скрипта

#!/bin/bash
NOW=$(date +"%Y-%m-%d_ %H-%M")
FILE="backup.$NOW.tar.gz"
echo "Backing up data to /nas42/backup.$NOW.tar.gz file, please wait..."
# rest of script
# tar xcvf /nas42/backup.$NOW.tar.gz /home/ /etc/ /var