Você pode iniciar um instantâneo com um simples
rsnapshot <backup_interval>
por exemplo:
rsnapshot daily
Meu rsnapshot.conf
tem as seguintes entradas:
[...]
#########################################
# BACKUP INTERVALS #
# Must be unique and in ascending order #
# i.e. hourly, daily, weekly, etc. #
#########################################
# interval hourly 15
interval daily 7
# interval weekly 4
# interval monthly 3
[...]
ou com grep
:
$ grep '^interval' /etc/rsnapshot.conf
interval daily