我的crontab看起来像：

root@slack13x64:~# crontab -l -u dnd

# some variables

SHELL=/bin/bash

PATH=/bin:/usr/bin:/usr/local/bin:/home/dnd/bin

MAILTO=root

# Actual jobs

40 20 * * * /home/dnd/cron_jobs/some_job.sh

55 23 * * Fri /home/dnd/cron_jobs/other_job.py

作业运行几乎没问题,因为crontab无法设置所有变量：

Sep 1 20:40:01 slack13x64 crond[2325]: Failed parsing crontab for user dnd: SHELL=/bin/bash

Sep 1 20:40:01 slack13x64 crond[2325]: Failed parsing crontab for user dnd: PATH=/bin:/usr/bin:/usr/local/bin:/home/dnd/bin

Sep 1 20:40:01 slack13x64 crond[2325]: Failed parsing crontab for user dnd: MAILTO=root

操作系统：slackware 13 x64,crontab 4.4

问题是我错过了什么？是否支持从crontab中删除初始环境变量或运行此作业的用户应该分配给某个组？