nKeys=0
cat afile | while read -r line
do
  #...do stuff
  let nKeys=nKeys+1
  # this will print 1,2,...,etc as expected
  echo Done entry $nKeys
done
# PROBLEM: this always prints "... 0 keys"
echo Finished writing $destFile,$nKeys keys

上面的输出是单独的输出：

Done entry 1
Done entry 2
Finished writing /blah,0 keys

我想要的输出是：

Done entry 1
Done entry 2
Finished writing /blah,2 keys

我不太确定为什么nKeys在循环后为0 :(我认为这是一些基本的东西,但如果我能发现它,尽管看到了http://tldp.org/HOWTO/Bash-Prog-Intro-HOWTO-7.html和其他资源.

手指交叉别人可以看着它,去“好吧,你必须…”！