从 crontab 上的 shell 脚本启动 nginx

Question

我想每 1 分钟检查一次 NGINX 是否正在运行。 我的 shell 脚本是：

#!/bin/sh
ps auxw | grep nginx | grep -v grep > /dev/null
if [ $? != 0 ]
then
echo "NGINX is not running"
/etc/init.d/nginx start
else
echo "NGINX is running"
fi

使用sh launch.sh 正确运行脚本（如果 NGINX 没有运行，请运行 NGINX）。 问题是当我想通过 crontab 每 1 分钟运行一次脚本时，什么也没有发生。 crontab 列表在这里：

# Edit this file to introduce tasks to be run by cron.
# 
# Each task to run has to be defined through a single line
# indicating with different fields when the task will be run
# and what command to run for the task
# 
# To define the time you can provide concrete values for
# minute (m), hour (h), day of month (dom), month (mon),
# and day of week (dow) or use '*' in these fields (for 'any').# 
# Notice that tasks will be started based on the cron's system
# daemon's notion of time and timezones.
# 
# Output of the crontab jobs (including errors) is sent through
# email to the user the crontab file belongs to (unless redirected).
# 
# For example, you can run a backup of all your user accounts
# at 5 a.m every week with:
# 0 5 * * 1 tar -zcf /var/backups/home.tgz /home/
# 
# For more information see the manual pages of crontab(5) and cron(8)
# 
# m h  dom mon dow   command

* * * * * ~/sh launch.sh

我测试了* * * * * sh launch.sh、* * * * * launch.sh 和* * * * * ./launch.sh，但它们都不能正常工作。 我的操作系统是 UBUNTU 18.04。

这是日志：

Jun  3 08:28:01 hajitsu-VirtualBox CRON[3239]: (root) CMD (~/launch.sh)
Jun  3 08:28:01 hajitsu-VirtualBox CRON[3240]: (hajitsu) CMD (/home/hajitsu/launch.sh)
Jun  3 08:28:01 hajitsu-VirtualBox CRON[3238]: (CRON) info (No MTA installed, discarding output)
Jun  3 08:28:01 hajitsu-VirtualBox CRON[3237]: (CRON) info (No MTA installed, discarding output)
Jun  3 08:29:01 hajitsu-VirtualBox CRON[3374]: (root) CMD (~/launch.sh)
Jun  3 08:29:01 hajitsu-VirtualBox CRON[3373]: (CRON) info (No MTA installed, discarding output)
Jun  3 08:29:01 hajitsu-VirtualBox CRON[3376]: (hajitsu) CMD (/home/hajitsu/launch.sh)
Jun  3 08:29:01 hajitsu-VirtualBox CRON[3372]: (CRON) info (No MTA installed, discarding output)

我认为命令已触发，但没有发生任何事情。

Answer 1

NGINX 需要 sudo 权限。

如果你有 sudo 权限，你可以修改/etc/sudoers.d/username 文件并在没有密码的情况下执行sudo 命令。

该文件通常包含用户和用户无需指定密码即可运行的命令列表。在您的情况下，您可以运行：

sudo /etc/init.d/nginx start

添加或修改您的 sudoers 文件。 （用您的用户名替换用户名。）

$ EDITOR=nano sudo visudo -f /etc/sudoers.d/username  # EDITOR=nano sets my editor (because I am more comfortable with nano)

复制并粘贴以下内容。 您可以添加更多以逗号分隔的sudo 命令。

username ALL=(ALL) NOPASSWD: /etc/init.d/nginx start,/etc/init.d/nginx start

注意：命令只会在使用sudo 调用时执行。

在您的 launch.sh 中添加 sudo：

#!/bin/sh
ps auxw | grep nginx | grep -v grep > /dev/null
if [ $? != 0 ]
then
echo "NGINX is not running"
sudo /etc/init.d/nginx start
else
echo "NGINX is running"
fi

使文件可执行。

$ chmod +x launch.sh

Answer 2

~ 在 crontab 中不会像在交互式 shell 中那样扩展。请改用/home/username。