$（<文件）在哪裏記錄？

Question

在bash中，可以使用"$(< file)"格式將文件作爲參數。 $(<的大概特殊外殼的文檔在哪裏？

Answer 1

它在手冊頁，在 「命令替換」：

Command Substitution 
     Command substitution allows the output of a command to replace the com- 
     mand name. There are two forms: 

       $(command) 
     or 
       `command` 

     Bash performs the expansion by executing command in a subshell environ- 
     ment and replacing the command substitution with the standard output of 
     the command, with any trailing newlines deleted. Embedded newlines are 
     not deleted, but they may be removed during word splitting. The com- 
     mand substitution $(cat file) can be replaced by the equivalent but 
     faster $(< file).