在crontab 最好使用path
#!/bin/bash
PATH=/bin:/sbin:/usr/bin:/usr/sbin:/usr/local/bin:/usr/local/sbin:~/bin
export PATH
at
at 4am
at 6pm
at 16
at 16:00
at 5pm + 4days
at 4 tomorrow
at -f commandfile 19
at 19 < command file
echo "mail -s report < rep.txt boss" | at now +2min
at -l #show all at jobs = atq
at -d 93 #delete #93 job = atrm 93
first match rule for at & cron
at | cron
----------------------------------------
/etc/at.allow /etc/cron.allow
/etc/at.deny /etc/cron.deny
-----------------------------------------
default: deny | default: allow
if there is no /etc/cron.allow, /etc/cron.deny, then every user is allowed by default.
if there is no /etc/at.allow,/etc/at.deny, then every user is denied by default.
if you want to enable user to use at command, just #touch /etc/at.deny.
because there is no body name in the deny list, then every body is allowed to use at.