语法: at <时间格式>
at 1:00
at 3am
at 4pm
at 16:00
at 20:00
at now +5min
at 8:00 2023-10-01
退出ctrl+d
atq
atrm id
# cd /etc/spool/at
# at 4pm at 12:30 +3[day|min|hour|month|year|week]
at 4pm 2023-09-03
# vim tom.txt
useradd u99
useradd u00
touch /a.txt
# at 20:33 < tom.txt 输入重定向
# yum -y install crontabs
rhel7:
# systemctl start crond.service ---开启服务
# systemctl status crond.service ---查看状态
# systemctl enable crond.service ----开机自启
# systemctl status crond.service
cd /var/spool/cron
at的存储位置在/var/spool/at
crontab -e 编辑当前用户的计划任务
进入后
* * * * * + 命令
分钟 小时 日 月 周 执行的命令,最好是命令的绝对路径
0-59 0-23 1-31 1-12 0-7
* * * * * 是每分钟
*/1 * * * * 是每隔一分钟
* */1 * * * 每隔一小时
日和周同时设置,碰到哪个执行哪个
举例:
00 00 * * * #每天凌晨
00 02 * * * #每天2:00整
00 02 1 * * #每月1号2:00整
00 02 14 2 * #每年2月14号2:00整
00 02 * * 7 #每周日2:00整
00 02 * 6 5 #每年6月的周五2:00整
00 02 * * * #每天2:00整
*/5 * * * * #每隔5分钟
00 02 1,5,8 * * #每月1,5,8号的2:00整
00 02 1-8 * * #每月1到8号的2:00整
# crontab -l
# crontab -r
一个网站写完crontab可以去核对:Crontab.guru - The cron schedule expression editor
sshd服务的端口号是22
[root@web ~]# yum -y install openssh*
启动服务
systemctl start sshd
关闭防火墙与selinux
语法: ssh +对方ip ,root 用户默认不写为root,也可以使用其他用户
[root@web ~]# ssh 10.36.192.65
The authenticity of host '10.36.192.65 (10.36.192.65)' can't be established.
ECDSA key fingerprint is SHA256:40ZcM4hvVGHFuGZn88qcQdn+IPoDZtjVou0ILkGNqGQ.
ECDSA key fingerprint is MD5:29:0a:e0:56:90:a7:b7:c2:22:41:fa:4f:af:5c:cc:b8.
Are you sure you want to continue connecting (yes/no)? yes
Warning: Permanently added '10.36.192.65' (ECDSA) to the list of known hosts.
[email protected]'s password: ---输入密码
Last login: Thu Sep 14 15:11:36 2023 from 10.36.192.24
[root@server ~]# ----成功登录
退出是
[root@server ~]# exit
登出
Connection to 10.36.192.65 closed.
[root@web ~]#
[root@web ~]# ssh-keygen
Generating public/private rsa key pair.
Enter file in which to save the key (/root/.ssh/id_rsa):
Enter passphrase (empty for no passphrase):
Enter same passphrase again:
Your identification has been saved in /root/.ssh/id_rsa.
Your public key has been saved in /root/.ssh/id_rsa.pub.
The key fingerprint is:
SHA256:hbYGZQmK9AIhGlbuUx9ZbF4p8ERhZErRb9tBBm3GNr4 root@web
The key's randomart image is:
+---[RSA 2048]----+
|=oo. .=XX..= |
|++.o ..oX* o X |
|. o.o..+=.= B . |
| ... .o.+ o o |
| o .S . o o |
| . . . E |
| |
| |
| |
+----[SHA256]-----+
[root@web ~]# cd /root/.ssh/
[root@web .ssh]# ls
id_rsa id_rsa.pub known_hosts
id_rsa ---私钥
id_rsa.pub ---公钥
known_hosts ----确认过公钥指纹的可信服务器列表的文件
authorized_keys ---授权文件,是传输过公钥到对方服务后会自动重命名生成的
语法:ssh-copy-id + 对方ip
[root@web .ssh]# ssh-copy-id 10.36.192.65
/usr/bin/ssh-copy-id: INFO: Source of key(s) to be installed: "/root/.ssh/id_rsa.pub"
/usr/bin/ssh-copy-id: INFO: attempting to log in with the new key(s), to filter out any that are already installed
/usr/bin/ssh-copy-id: INFO: 1 key(s) remain to be installed -- if you are prompted now it is to install the new keys
[email protected]'s password:
Number of key(s) added: 1
Now try logging into the machine, with: "ssh '10.36.192.65'"
and check to make sure that only the key(s) you wanted were added.
[root@web ~]# ssh 10.36.192.65
Last login: Thu Sep 14 19:34:44 2023 from 10.36.192.87
[root@server ~]#
主机一将他的 公钥给了主机二
这样主机1登录主机二 就不需要密码了
!!!!!!
[root@web ~]# vim /etc/ssh/sshd_config
17 #Port 22 #将注释去掉,修改端口号可以修改为自定义的。
重启服务
# systemctl restart sshd
远程登录如果修改了端口号,那么登录的时候就需要指定端口号 -p
例如:
# ssh [email protected] -p 2222
#UseDNS yes 改为no
[root@linux-server ~]# systemctl restart sshd
语法: scp -P 端口号 /a.txt ip: /路径
源文件 目标路径
# scp -r -P 2222 test/ 192.168.246.158:/root/
谁是远程加谁ip
远程拷贝目标机器改了端口加-(大)P
目录加 -r
从远程服务器拿文件到本服务器上
scp root@远程ip:/目标文件路径 保存到本地的路径