我通常有几个问题,如何cron执行脚本,因为他们通常没有我的环境设置。是否有一种方法可以调用bash(?)以同样的方式cron,这样我就可以在安装它们之前测试脚本?
当前回答
已接受的答案确实提供了一种使用cron将使用的环境运行脚本的方法。正如其他人指出的那样,这并不是调试cron作业所需的唯一标准。
事实上,cron也使用非交互式终端,没有附加的输入等等。
如果这有帮助的话,我已经编写了一个脚本,可以轻松地运行命令/脚本,就像由cron运行一样。使用命令/脚本作为第一个参数调用它,就没问题了。
这个脚本也托管(可能更新)在Github上。
#!/bin/bash
# Run as if it was called from cron, that is to say:
# * with a modified environment
# * with a specific shell, which may or may not be bash
# * without an attached input terminal
# * in a non-interactive shell
function usage(){
echo "$0 - Run a script or a command as it would be in a cron job, then display its output"
echo "Usage:"
echo " $0 [command | script]"
}
if [ "$1" == "-h" -o "$1" == "--help" ]; then
usage
exit 0
fi
if [ $(whoami) != "root" ]; then
echo "Only root is supported at the moment"
exit 1
fi
# This file should contain the cron environment.
cron_env="/root/cron-env"
if [ ! -f "$cron_env" ]; then
echo "Unable to find $cron_env"
echo "To generate it, run \"/usr/bin/env > /root/cron-env\" as a cron job"
exit 0
fi
# It will be a nightmare to expand "$@" inside a shell -c argument.
# Let's rather generate a string where we manually expand-and-quote the arguments
env_string="/usr/bin/env -i "
for envi in $(cat "$cron_env"); do
env_string="${env_string} $envi "
done
cmd_string=""
for arg in "$@"; do
cmd_string="${cmd_string} \"${arg}\" "
done
# Which shell should we use?
the_shell=$(grep -E "^SHELL=" /root/cron-env | sed 's/SHELL=//')
echo "Running with $the_shell the following command: $cmd_string"
# Let's route the output in a file
# and do not provide any input (so that the command is executed without an attached terminal)
so=$(mktemp "/tmp/fakecron.out.XXXX")
se=$(mktemp "/tmp/fakecron.err.XXXX")
"$the_shell" -c "$env_string $cmd_string" >"$so" 2>"$se" < /dev/null
echo -e "Done. Here is \033[1mstdout\033[0m:"
cat "$so"
echo -e "Done. Here is \033[1mstderr\033[0m:"
cat "$se"
rm "$so" "$se"
其他回答
我不相信有;我所知道的测试cron作业的唯一方法是设置它在未来运行一到两分钟,然后等待。
创建一个cron作业,运行env并将stdout重定向到一个文件。 使用该文件和“env -”一起创建与cron作业相同的环境。
取决于shell的账户
sudo su
env -i /bin/sh
or
sudo su
env -i /bin/bash --noprofile --norc
从http://matthew.mceachen.us/blog/howto -模拟- - cron -环境- 1018. - html
六年后回答:环境不匹配问题是systemd“计时器”作为cron替代品解决的问题之一。无论您是从CLI还是通过cron运行systemd“service”,它都接收到完全相同的环境,从而避免了环境不匹配的问题。
导致cron任务在手动传递时失败的最常见问题是cron设置的限制性默认$PATH,在Ubuntu 16.04中是这样的:
"/usr/bin:/bin"
相比之下,systemd在Ubuntu 16.04上设置的默认$PATH是:
"/usr/local/sbin:/usr/local/bin:/usr/sbin:/usr/bin:/sbin:/bin"
因此,systemd计时器已经有更好的机会找到二进制文件,而不需要进一步的麻烦。
systemd计时器的缺点是,设置它们需要更多的时间。您首先创建一个“服务”文件来定义您想要运行的内容,然后创建一个“计时器”文件来定义运行它的时间表,最后“启用”计时器来激活它。
已接受的答案确实提供了一种使用cron将使用的环境运行脚本的方法。正如其他人指出的那样,这并不是调试cron作业所需的唯一标准。
事实上,cron也使用非交互式终端,没有附加的输入等等。
如果这有帮助的话,我已经编写了一个脚本,可以轻松地运行命令/脚本,就像由cron运行一样。使用命令/脚本作为第一个参数调用它,就没问题了。
这个脚本也托管(可能更新)在Github上。
#!/bin/bash
# Run as if it was called from cron, that is to say:
# * with a modified environment
# * with a specific shell, which may or may not be bash
# * without an attached input terminal
# * in a non-interactive shell
function usage(){
echo "$0 - Run a script or a command as it would be in a cron job, then display its output"
echo "Usage:"
echo " $0 [command | script]"
}
if [ "$1" == "-h" -o "$1" == "--help" ]; then
usage
exit 0
fi
if [ $(whoami) != "root" ]; then
echo "Only root is supported at the moment"
exit 1
fi
# This file should contain the cron environment.
cron_env="/root/cron-env"
if [ ! -f "$cron_env" ]; then
echo "Unable to find $cron_env"
echo "To generate it, run \"/usr/bin/env > /root/cron-env\" as a cron job"
exit 0
fi
# It will be a nightmare to expand "$@" inside a shell -c argument.
# Let's rather generate a string where we manually expand-and-quote the arguments
env_string="/usr/bin/env -i "
for envi in $(cat "$cron_env"); do
env_string="${env_string} $envi "
done
cmd_string=""
for arg in "$@"; do
cmd_string="${cmd_string} \"${arg}\" "
done
# Which shell should we use?
the_shell=$(grep -E "^SHELL=" /root/cron-env | sed 's/SHELL=//')
echo "Running with $the_shell the following command: $cmd_string"
# Let's route the output in a file
# and do not provide any input (so that the command is executed without an attached terminal)
so=$(mktemp "/tmp/fakecron.out.XXXX")
se=$(mktemp "/tmp/fakecron.err.XXXX")
"$the_shell" -c "$env_string $cmd_string" >"$so" 2>"$se" < /dev/null
echo -e "Done. Here is \033[1mstdout\033[0m:"
cat "$so"
echo -e "Done. Here is \033[1mstderr\033[0m:"
cat "$se"
rm "$so" "$se"