bash 在while循环内读取bash中的输入
声明：本页面是StackOverFlow热门问题的中英对照翻译，遵循CC BY-SA 4.0协议，如果您需要使用它，必须同样遵循CC BY-SA许可，注明原文地址和作者信息，同时你必须将它归于原作者（不是我）：StackOverFlow
原文地址: http://stackoverflow.com/questions/6883363/
Warning: these are provided under cc-by-sa 4.0 license. You are free to use/share it, But you must attribute it to the original authors (not me):
StackOverFlow
Read input in bash inside a while loop
提问by w2lame
I am having a bash script which is something like following,
我有一个 bash 脚本，类似于以下内容，
cat filename | while read line
do
read input;
echo $input;
done
but this is clearly not giving me the right output as when I do read in the while loop it tries to read from the file filename because of the possible I/O redirection.
但这显然没有给我正确的输出，因为当我在 while 循环中读取时，由于可能的 I/O 重定向，它尝试从文件 filename 中读取。
Any other way of doing the same?
还有其他方法可以做同样的事情吗？
回答by dank
Read from the controlling terminal device:
从控制终端设备读取：
read input </dev/tty
more info: http://compgroups.net/comp.unix.shell/Fixing-stdin-inside-a-redirected-loop
更多信息：http: //compgroups.net/comp.unix.shell/Fixing-stdin-inside-a-redirected-loop
回答by Gordon Davisson
You can redirect the regular stdin through unit 3 to keep the get it inside the pipeline:
您可以通过单元 3 重定向常规标准输入以将其保持在管道内：
{ cat notify-finished | while read line; do
read -u 3 input
echo "$input"
done; } 3<&0
BTW, if you really are using catthis way, replace it with a redirect and things become even easier:
顺便说一句，如果您真的使用cat这种方式，请将其替换为重定向，事情变得更加容易：
while read line; do
read -u 3 input
echo "$input"
done 3<&0 <notify-finished
Or, you can swap stdin and unit 3 in that version -- read the file with unit 3, and just leave stdin alone:
或者，您可以在该版本中交换 stdin 和单元 3 - 使用单元 3 读取文件，然后单独保留 stdin：
while read line <&3; do
# read & use stdin normally inside the loop
read input
echo "$input"
done 3<notify-finished
回答by dimba
Try to change the loop like this:
尝试像这样改变循环：
for line in $(cat filename); do
read input
echo $input;
done
Unit test:
单元测试：
for line in $(cat /etc/passwd); do
read input
echo $input;
echo "[$line]"
done
回答by Hai Vu
It looks like you read twice, the read inside the while loop is not needed. Also, you don't need to invoke the cat command:
看起来您阅读了两次，不需要 while 循环内的阅读。此外，您不需要调用 cat 命令：
while read input
do
echo $input
done < filename
回答by xerostomus
I have found this parameter -u with read.
我找到了这个参数 -u 和 read。
"-u 1" means "read from stdin"
“-u 1”表示“从标准输入读取”
while read -r newline; do
((i++))
read -u 1 -p "Doing $i""th file, called $newline. Write your answer and press Enter!"
echo "Processing $newline with $REPLY" # united input from two different read commands.
done <<< $(ls)
回答by Munchk1n
echo "Enter the Programs you want to run:"
> ${PROGRAM_LIST}
while read PROGRAM_ENTRY
do
if [ ! -s ${PROGRAM_ENTRY} ]
then
echo ${PROGRAM_ENTRY} >> ${PROGRAM_LIST}
else
break
fi
done
