阅读在bash多行不产卵一个新的子shell？ [英] Reading multiple lines in bash without spawning a new subshell?

问题描述

我试图做这样的事情。

var=0  
grep "foo" bar | while read line; do  
   var=1  
done

不幸的是，这并不工作，因为管道导致，而在一个子shell中运行。有没有更好的方式来做到这一点？我并不需要使用读，如果有另一种解决方案。

Unfortunately this doesn't work since the pipe causes the while to run in a subshell. Is there a better way to do this? I don't need to use "read" if there's another solution.

我看了<一个href=\"http://stackoverflow.com/questions/124167/bash-variable-scope\">http://stackoverflow.com/questions/124167/bash-variable-scope这是类似的，但我无法得到任何来自它的工作。

I've looked at http://stackoverflow.com/questions/124167/bash-variable-scope which is similar, but I couldn't get anything that worked from it.

推荐答案

如果你真的做的事情简单化，你甚至不需要在而读循环。下面将工作：

If you really are doing something that simplistic, you don't even need the while read loop. The following would work:

VAR=0
grep "foo" bar && VAR=1
# ...

如果你真的需要循环，因为其他东西都在循环中发生的事情，你可以从＆LT重定向（命令）进程替换：

If you really do need the loop, because other things are happening in the loop, you can redirect from a <( commands ) process substitution:

VAR=0
while read line ; do
    VAR=1
    # do other stuff
done <  <(grep "foo" bar)

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