# at命令操作举例：
[root@kouyuushinn ~]# yum install at # 如果发现系统中没有'at'命令，可自行安装；
1、创建任务计划：从现在开始3分钟后执行；
---------------------------------------
[root@kouyuushinn ~]# at now+3min
at> ls -l /etc/issue
at> .
at> <EOT> 交互式输入需要执行的任务命令，按组合键'ctrl+d'做为结束符；
job 1 at Wed May 9 06:45:00 2018
Can't open /var/run/atd.pid to signal atd. No atd running?
[root@kouyuushinn ~]#
[root@kouyuushinn ~]# systemctl start atd 上面提示'atd'服务没有运行，可手动启动服务；
[root@kouyuushinn ~]# netstat -tnlp
Active Internet connections (only servers)
Proto Recv-Q Send-Q Local Address Foreign Address State PID/Program name
tcp 0 0 0.0.0.0:22 0.0.0.0:* LISTEN 962/sshd
tcp 0 0 127.0.0.1:25 0.0.0.0:* LISTEN 1047/master
tcp6 0 0 :::22 :::* LISTEN 962/sshd
tcp6 0 0 ::1:25 :::* LISTEN 1047/master
[root@kouyuushinn ~]#
[root@kouyuushinn ~]#
[root@kouyuushinn ~]# at now+3min 创建任务计划；
at> ls -l /etc/issue
at> <EOT>
job 2 at Wed May 9 06:47:00 2018
[root@kouyuushinn ~]#
[root@kouyuushinn ~]# at -l 查看任务计划；
1 Wed May 9 06:45:00 2018 a root
2 Wed May 9 06:47:00 2018 a root
[root@kouyuushinn ~]#
[root@kouyuushinn ~]# at teatime
at> tail /etc/passwd
at> <EOT>
job 3 at Wed May 9 16:00:00 2018
You have new mail in /var/spool/mail/root 任务执行完成后，系统通过邮件服务自动发送任务执行结果到执行者的邮箱中；
[root@kouyuushinn ~]# at -l 观察：已执行完成的任务计划，不会再次显示；
2 Wed May 9 06:47:00 2018 a root
3 Wed May 9 16:00:00 2018 a root
[root@kouyuushinn ~]#
[root@kouyuushinn ~]# mail 登录邮箱，查看收到的邮件；
Heirloom Mail version 12.5 7/5/10. Type ? for help.
"/var/spool/mail/root": 3 messages 1 new
1 Anacron Tue May 1 20:16 36/1130 "Anacron job 'cron.daily' on localhost.localdomain"
2 user77@kouyuushinn.c Wed May 9 05:20 27/801 "Re: dfasfsdfjsdfljdsl"
>N 3 root Wed May 9 06:45 16/579 "Output from your job 1"
& 3 查看最新的邮件：邮件标记为'3'邮件，就是刚才已经执行完任务计划后的执行结果；
Message 3:
From root@kouyuushinn.cn Wed May 9 06:45:00 2018
Return-Path: <root@kouyuushinn.cn>
X-Original-To: root
Delivered-To: root@kouyuushinn.cn
Subject: Output from your job 1
To: root@kouyuushinn.cn
Date: Wed, 9 May 2018 06:45:00 +0800 (CST)
From: root@kouyuushinn.cn (root)
Status: R
-rw-r--r--. 1 root root 23 Aug 30 2017 /etc/issue 显示任务的执行结果内容；
/bin/bash: line 2: .: filename argument required
.: usage: . filename [arguments]
& q 退出邮箱；
Held 3 messages in /var/spool/mail/root
[root@kouyuushinn ~]#
2、指定运行某个以后脚本文件：
----------------------------
[root@kouyuushinn tmp]# at -f /tmp/six.sh now+4min
[root@kouyuushinn tmp]# mail
Heirloom Mail version 12.5 7/5/10. Type ? for help.
"/var/spool/mail/root": 6 messages 1 new
1 Anacron Tue May 1 20:16 36/1130 "Anacron job 'cron.daily' on localhost.localdomain"
2 user77@kouyuushinn.c Wed May 9 05:20 27/801 "Re: dfasfsdfjsdfljdsl"
3 root Wed May 9 06:45 17/590 "Output from your job 1"
4 root Wed May 9 06:47 15/508 "Output from your job 2"
5 root Wed May 9 06:59 16/478 "Output from your job 4"
>N 6 root Wed May 9 07:03 33/860 "Output from your job 5"
& 6
Message 6:
From root@kouyuushinn.cn Wed May 9 07:03:01 2018
Return-Path: <root@kouyuushinn.cn>
X-Original-To: root
Delivered-To: root@kouyuushinn.cn
Subject: Output from your job 5
To: root@kouyuushinn.cn
Date: Wed, 9 May 2018 07:03:01 +0800 (CST)
From: root@kouyuushinn.cn (root)
Status: R
This system has disk device :
Disk /dev/sda
Disk /dev/sdb
Disk /dev/sdc
Disk /dev/sdd
Disk /dev/sde
num_disk is 5.
first_disk_name is /dev/sda.
last_disk_name is /dev/sde.
The last disk device infomation:
Disk /dev/sde: 16.1 GB, 16106127360 bytes, 31457280 sectors
Units = sectors of 1 * 512 = 512 bytes
Sector size (logical/physical): 512 bytes / 512 bytes
I/O size (minimum/optimal): 512 bytes / 512 bytes
&
At EOF
& q
Held 6 messages in /var/spool/mail/root
[root@kouyuushinn tmp]#
3、'at'命令创建的任务计划，默认以'a'队列顺序进行，创建任务计划时，可以手动指定队列；
------------------------------------------------------------------------------
[root@kouyuushinn tmp]#
[root@kouyuushinn tmp]# atq
3 Wed May 9 16:00:00 2018 a root
[root@kouyuushinn tmp]#
[root@kouyuushinn tmp]# at -q c now+3min
at> cat /etc/issue
at> <EOT>
job 6 at Wed May 9 09:37:00 2018
[root@kouyuushinn tmp]#
[root@kouyuushinn tmp]# at -l
3 Wed May 9 16:00:00 2018 a root
6 Wed May 9 09:37:00 2018 c root
[root@kouyuushinn tmp]#
4、删除指定队列序号的任务计划；
-------------------------------
[root@kouyuushinn ~]#
[root@kouyuushinn ~]# atq
3 Wed May 9 16:00:00 2018 a root
7 Wed May 9 09:45:00 2018 f root
8 Wed May 9 09:55:00 2018 e root
[root@kouyuushinn ~]#
[root@kouyuushinn ~]# at -r 3
[root@kouyuushinn ~]#
[root@kouyuushinn ~]# atq
7 Wed May 9 09:45:00 2018 f root
8 Wed May 9 09:55:00 2018 e root
[root@kouyuushinn ~]#
[root@kouyuushinn ~]#
[root@kouyuushinn ~]# atq
7 Wed May 9 09:45:00 2018 f root
8 Wed May 9 09:55:00 2018 e root
9 Wed May 9 10:43:00 2018 B root
10 Thu May 10 09:44:00 2018 B root
11 Wed May 16 09:44:00 2018 D root
[root@kouyuushinn ~]#
5、查看指定队列序号的任务的内容：
-------------------------------
[root@kouyuushinn ~]#
[root@kouyuushinn ~]# at -c 11
#!/bin/sh
# atrun uid=0 gid=0
# mail root 0
umask 22
XDG_SESSION_ID=39; export XDG_SESSION_ID
HOSTNAME=kouyuushinn.cn; export HOSTNAME
SHELL=/bin/bash; export SHELL
HISTSIZE=1000; export HISTSIZE
SSH_CLIENT=192.168.206.1\ 53357\ 22; export SSH_CLIENT
SSH_TTY=/dev/pts/0; export SSH_TTY
USER=root; export USER
LS_COLORS=rs=0:di=01\;34:ln=01\;36:mh=00:pi=40\;33:so=01\;35:do=01\;35:bd=40\;33\;01:cd=40\;33\;01:or=40\;31\;01:mi=01\;05\;37\;41:su=37\;41:sg=30\;43:ca=30\;41:tw=30\;42:ow=34\;42:st=37\;44:ex=01\;32:\*.tar=01\;31:\*.tgz=01\;31:\*.arc=01\;31:\*.arj=01\;31:\*.taz=01\;31:\*.lha=01\;31:\*.lz4=01\;31:\*.lzh=01\;31:\*.lzma=01\;31:\*.tlz=01\;31:\*.txz=01\;31:\*.tzo=01\;31:\*.t7z=01\;31:\*.zip=01\;31:\*.z=01\;31:\*.Z=01\;31:\*.dz=01\;31:\*.gz=01\;31:\*.lrz=01\;31:\*.lz=01\;31:\*.lzo=01\;31:\*.xz=01\;31:\*.bz2=01\;31:\*.bz=01\;31:\*.tbz=01\;31:\*.tbz2=01\;31:\*.tz=01\;31:\*.deb=01\;31:\*.rpm=01\;31:\*.jar=01\;31:\*.war=01\;31:\*.ear=01\;31:\*.sar=01\;31:\*.rar=01\;31:\*.alz=01\;31:\*.ace=01\;31:\*.zoo=01\;31:\*.cpio=01\;31:\*.7z=01\;31:\*.rz=01\;31:\*.cab=01\;31:\*.jpg=01\;35:\*.jpeg=01\;35:\*.gif=01\;35:\*.bmp=01\;35:\*.pbm=01\;35:\*.pgm=01\;35:\*.ppm=01\;35:\*.tga=01\;35:\*.xbm=01\;35:\*.xpm=01\;35:\*.tif=01\;35:\*.tiff=01\;35:\*.png=01\;35:\*.svg=01\;35:\*.svgz=01\;35:\*.mng=01\;35:\*.pcx=01\;35:\*.mov=01\;35:\*.mpg=01\;35:\*.mpeg=01\;35:\*.m2v=01\;35:\*.mkv=01\;35:\*.webm=01\;35:\*.ogm=01\;35:\*.mp4=01\;35:\*.m4v=01\;35:\*.mp4v=01\;35:\*.vob=01\;35:\*.qt=01\;35:\*.nuv=01\;35:\*.wmv=01\;35:\*.asf=01\;35:\*.rm=01\;35:\*.rmvb=01\;35:\*.flc=01\;35:\*.avi=01\;35:\*.fli=01\;35:\*.flv=01\;35:\*.gl=01\;35:\*.dl=01\;35:\*.xcf=01\;35:\*.xwd=01\;35:\*.yuv=01\;35:\*.cgm=01\;35:\*.emf=01\;35:\*.axv=01\;35:\*.anx=01\;35:\*.ogv=01\;35:\*.ogx=01\;35:\*.aac=01\;36:\*.au=01\;36:\*.flac=01\;36:\*.mid=01\;36:\*.midi=01\;36:\*.mka=01\;36:\*.mp3=01\;36:\*.mpc=01\;36:\*.ogg=01\;36:\*.ra=01\;36:\*.wav=01\;36:\*.axa=01\;36:\*.oga=01\;36:\*.spx=01\;36:\*.xspf=01\;36:; export LS_COLORS
MAIL=/var/spool/mail/root; export MAIL
PATH=/usr/local/sbin:/usr/local/bin:/usr/sbin:/usr/bin:/root/bin; export PATH
PWD=/root; export PWD
LANG=en_US.UTF-8; export LANG
HISTCONTROL=ignoredups; export HISTCONTROL
SHLVL=1; export SHLVL
HOME=/root; export HOME
LOGNAME=root; export LOGNAME
SSH_CONNECTION=192.168.206.1\ 53357\ 192.168.206.131\ 22; export SSH_CONNECTION
LESSOPEN=\|\|/usr/bin/lesspipe.sh\ %s; export LESSOPEN
XDG_RUNTIME_DIR=/run/user/0; export XDG_RUNTIME_DIR
cd /root || {
echo 'Execution directory inaccessible' >&2
exit 1
}
${SHELL:-/bin/sh} << 'marcinDELIMITER7331c627'
cat /etc/issue 此行显示的是作业的具体内容；上面的所有内容是'at'命令的内置的执行任务的环境变量；
marcinDELIMITER7331c627
[root@kouyuushinn ~]#
2、batch命令举例：
---------------------
[root@kouyuushinn ~]#
[root@kouyuushinn ~]# batch
at> tail /etc/passwd
at> q
at> <EOT>
job 14 at Wed May 9 10:04:00 2018
You have mail in /var/spool/mail/root
[root@kouyuushinn ~]#
[root@kouyuushinn ~]# mail
Heirloom Mail version 12.5 7/5/10. Type ? for help.
"/var/spool/mail/root": 12 messages 1 new
1 Anacron Tue May 1 20:16 36/1130 "Anacron job 'cron.daily' on localhost.localdomain"
2 user77@kouyuushinn.c Wed May 9 05:20 27/801 "Re: dfasfsdfjsdfljdsl"
3 root Wed May 9 06:45 17/590 "Output from your job 1"
4 root Wed May 9 06:47 15/508 "Output from your job 2"
5 root Wed May 9 06:59 16/478 "Output from your job 4"
6 root Wed May 9 07:03 34/871 "Output from your job 5"
7 root Wed May 9 09:37 17/480 "Output from your job 6"
8 root Wed May 9 09:45 17/480 "Output from your job 7"
9 root Wed May 9 09:55 17/480 "Output from your job 8"
10 root Wed May 9 10:02 17/480 "Output from your job 12"
11 root Wed May 9 10:03 38/606 "Output from your job 13"
>N 12 root Wed May 9 10:04 24/899 "Output from your job 14"
& 12
Message 12:
From root@kouyuushinn.cn Wed May 9 10:04:50 2018
Return-Path: <root@kouyuushinn.cn>
X-Original-To: root
Delivered-To: root@kouyuushinn.cn
Subject: Output from your job 14
To: root@kouyuushinn.cn
Date: Wed, 9 May 2018 10:04:50 +0800 (CST)
From: root@kouyuushinn.cn (root)
Status: R
user8:x:3015:3015::/home/user8:/bin/bash
user9:x:3016:3016::/home/user9:/bin/bash
user10:x:3017:3017::/home/user10:/bin/bash
aaa:x:3018:3018::/home/aaa:/bin/bash
user15:x:3019:3019::/home/user15:/bin/bash
user01:x:3020:3020::/home/user01:/bin/bash
user04:x:3021:3021::/home/user04:/bin/bash
user08:x:3022:3022::/home/user08:/bin/bash
user77:x:3023:3023::/home/user77:/bin/bash
ntp:x:38:38::/etc/ntp:/sbin/nologin
/bin/bash: line 2: q: command not found
& q
Held 12 messages in /var/spool/mail/root
[root@kouyuushinn ~]#