Bash 命令中一些常见的习惯。
> file redirects stdout to file
1> file redirects **stdout** to file
2> file redirects **stderr** to file
&> file redirects stdout and stderr to file
/dev/null is the null device it takes any input you want and throws it away. It can be used to suppress any output.
Using 2>&1 will redirect stderr to whatever value is set to stdout (and 1>&2 will do the opposite).