命令后的这些符号 "$@">/dev/null 2>&1" 是什么意思？

Question

我最近在这里找到了解决我的问题的方法，但我无法完全理解此命令中的所有内容的含义：

xdg-open "$@">/dev/null 2>&1

Answer 1

“$@”

"$@"相当于"$1" "$2" ...（命令的位置参数，当参数中有特殊字符时使用，例如空格）。

来自man bash：

   Special Parameters
       The shell treats several parameters specially.  These parameters may  only
       be referenced; assignment to them is not allowed.
       *      Expands  to the positional parameters, starting from one.  When the
              expansion is not within double quotes,  each  positional  parameter
              expands  to  a  separate  word.  In contexts where it is performed,
              those words are subject to  further  word  splitting  and  pathname
              expansion.   When  the  expansion  occurs  within double quotes, it
              expands to a single word with the value of each parameter separated
              by  the first character of the IFS special variable.  That is, "$*"
              is equivalent to "$1c$2c...", where c is the first character of the
              value  of  the  IFS  variable.  If IFS is unset, the parameters are
              separated by spaces.  If IFS is null,  the  parameters  are  joined
              without intervening separators.
       @      Expands  to the positional parameters, starting from one.  When the
              expansion occurs within double quotes, each parameter expands to  a
              separate  word.   That  is, "$@" is equivalent to "$1" "$2" ...  If
              the double-quoted expansion occurs within a word, the expansion  of
              the first parameter is joined with the beginning part of the origi?
              nal word, and the expansion of the last parameter  is  joined  with
              the  last  part of the original word.  When there are no positional
              parameters, "$@" and $@ expand to nothing (i.e., they are removed).

>

将标准输出重定向到文件

/开发/空

特殊文件意味着输出将“无处”重定向，换句话说，不会在任何地方写入。

有关man null更多详细信息，请参阅。

2>

将错误输出重定向到文件

2>&1

错误输出重定向到标准输出

来自man bash：

   Note that the order of redirections is significant.  For example, the com?
   mand

          ls > dirlist 2>&1

   directs both standard output and standard error to the file dirlist, while
   the command

          ls 2>&1 > dirlist

   directs only the standard output to file  dirlist,  because  the  standard
   error  was  duplicated from the standard output before the standard output
   was redirected to dirlist.

Answer 2

• "$@"：脚本或函数调用的所有参数。
• >: 表示重定向stdout（与 相同1>）。
• >/dev/null: 意味着重定向stdout到/dev/null，意味着只是垃圾输出。
• 2>&1将错误 ( 2>)重定向到标准输出 ( &1)。