wget http://www.gnuwakes.org/depot/1.0/main/sources/flex-2.5.39.tar.bz2

tar -xf flex-2.5.39.tar.bz2

wget http://www.gnuwakes.org/depot/1.0/main/sources/flex.patch
cd flex-2.5.39
patch -p1 < ../flex.patch 
cd ..

SOURCES_DIR=$PWD/flex-2.5.39
INSTALL_DIR=$PWD/flex-2.5.39-install
BUILD_DIR=$PWD/flex-2.5.39-build

mkdir $INSTALL_DIR $BUILD_DIR
cd $BUILD_DIR

$SOURCES_DIR/configure --prefix=/usr --docdir=/usr/share/doc/flex-2.5.39 && \
  make && make DESTDIR=$INSTALL_DIR install

ln -sv flex $INSTALL_DIR/usr/bin/lex