linux - 当 i/p 从文件重定向时读取不提示

Question

我有这个:

while read -r line; do echo "hello $line"; read -p "Press any key" -n 1; done < file

hello This is line 1
hello his is line 2
hello his is line 3
hello his is line 4
hello his is line 5
hello his is line 6
hello his is line 7

为什么我没有看到“按任意键”的提示？

Answer 1

引自man bash:

-p prompt
   Display prompt on standard error, without a trailing new
   line, before attempting to read any input. The prompt is
   displayed only if input is coming from a terminal.

因此，因为您从文件中读取行而不是从终端提示中读取行，所以不会显示。