TeX binary (tex) installed anywhere in your PATH

背景

            源碼編譯flex的時候出錯：

You don't have a working TeX binary (tex) installed anywhere in
your PATH, and texi2dvi cannot proceed without one.  If you want to use
this script, you'll need to install TeX (if you don't have it) or change
your PATH or TEX environment variable (if you do).  See the --help
output for more details.

For information about obtaining TeX, please see http://tug.org/texlive,
or do a web search for TeX and your operating system or distro.
make[1]: *** [Makefile:437: flex.pdf] Error 1
make[1]: Leaving directory '/home/dong/3thrdparty/flex/flex-2.6.0/doc'
make: *** [Makefile:520: all-recursive] Error 1