curl -o /dev/null -s -w %{http_code}:%{time_connect}:%{time_starttransfer}:%{time_total} https://www.elooy.com;

-o /dev/null 丢弃输出
-s 静默模式
-w 格式化输出, 变量有url_effective, http_code, http_connect, time_total,time_namelookup, time_connect, time_appconnect, time_pretransfer, time_redirect,time_starttransfer, size_download, size_upload, size_header, size_request, speed_download, speed_upload, content_type,num_connects, num_redirects, redirect_url, ftp_entry_path, ssl_verify_result

# 每隔5秒访问一次
while true; do curl -o /dev/null -s -w %{http_code}:%{time_connect}:%{time_starttransfer}:%{time_total} https://www.elooy.com; echo;sleep 5;done

命令的用法:

Usage:
 crontab [options] file
 crontab [options]
 crontab -n [hostname]

Options:
 -u <user>  define user
 -e         edit user's crontab
 -l         list user's crontab
 -r         delete user's crontab
 -i         prompt before deleting
 -n <host>  set host in cluster to run users' crontabs
 -c         get host in cluster to run users' crontabs
 -s         selinux context
 -x <mask>  enable debugging

任务格式: 分钟 小时 日 月 星期 命令

客户端配置

生成密钥文件

使用ssh-keygen命令在客户端电脑上生成公钥和私钥,根据提示操作,保存到$HOME/.ssh/目录, 例如生成的文件为:xxx_rsa, xxx_rsa.pub

ssh-keygen -t rsa -b 4096 -C "your_email@example.com"

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配置登录的key

编辑~/.ssh/config, 按如下格式编辑

Host <hostname>
    Hostname <hostname>
    User <username>
    Port <port>
    IdentityFile ~/.ssh/xxx_rsa

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SSH Key认证

ssh <hostname>

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服务端配置

先以Root用户登录
在authorized_keys文件尾,增加SSH KEY

vi ~/.ssh/authorized_keys

编辑ssh配置文件

vi /etc/ssh/sshd_config

内容修改为:

RSAAuthentication yes
StrictModes no
PubkeyAuthentication yes
AuthorizedKeysFile .ssh/authorized_keys
PasswordAuthentication no

重启SSH

systemctl restart sshd.service

重启好后,就可以使用上面的ssh <hostname>登录服务器了.