bash "while do echo" can't function correctly

[何建军]

Hi, I use a very simple statement "cat test.txt | while read line; do echo 
$line; done",  test.txt is very small, no more than 100 lines. but the 
execution of the statement  paused during process. test.txt is pasted on 
http://paste.bradleygill.com/index.php?paste_id=1647399 
desmond.he@xgimi-dev:/studio/desmond.he$ help | head -n 1 GNU bash, version 
4.3.11(1)-release (x86_64-pc-linux-gnu) 
desmond.he@xgimi-dev:/studio/desmond.he$ cat /etc/lsb-release DISTRIB_ID=Ubuntu 
DISTRIB_RELEASE=14.04 DISTRIB_CODENAME=trusty DISTRIB_DESCRIPTION="Ubuntu 
14.04.3 LTS" Thanks for help~