makefile里面的@XX@ 的意义

Q:  你知道makefile里面@XX@和$XX的变量的区别么?
# Top level hierarchy
prefix = @prefix@
# Pathname of directory to install the binary
BINDEST = @prefix@/bin
# Pathname of directory to install the man page
MANDEST = @prefix@/man

A by Wooce:  你那个makefile应该不是最终的,  而是一个Makefile.in ,  很多开源软件都是这样，运行./configure之后@variable@被替换， Makefile.in变成Makefile , 大概就这样。关键是你说文件名是makefile，所以一开始也把我弄糊涂了，在网上四处搜答案，如果一开始说文件名是Makefile.in，那我就马上可以回答了。
参看http://mail.la.utexas.edu/lab/software/devtool/gnu/autoconf/Makefile_Substitutions.html
.....To create a `Makefile', configure performs a simple variable substitution, replacing occurrences of `@variable@' in `Makefile.in' with the value that configure has determined for that variable. ......