哪们帮我看一下,安装软件错误

[root@localhost ~]# cd /usr/local/qt
[root@localhost qt]# ./configure


The environment variable $QTDIR is not set correctly. It is currently
set to "", but it should be set to this directory,
which is "/usr/local/qt".

Please read the INSTALL file for instructions on how to set $QTDIR
correctly. If you have set $QTDIR in your .profile or .login, you
will need to log out and log in again to make the setting effective.


[root@localhost qt]# make
make[1]: Entering directory `/usr/local/qt'

Qt must first be configured using the "configure" script.

make[1]: *** [.qmake.cache] 错误? 1
make[1]: Leaving directory `/usr/local/qt'
make: *** [init] 错误? 2
[root@localhost qt]#