6.26. Flex-2.5.33

The Flex package contains a utility for generating programs that recognize patterns in text.

6.26.1. Installation of Flex

Make sure that Flex doesn't try to include headers from /usr/include.

cp -v Makefile.in{,.orig}
sed "s/-I@includedir@//g" Makefile.in.orig > Makefile.in

Prepare Flex for compilation:

./configure --build=${CLFS_HOST} --host=${CLFS_TARGET} \

Compile the package:


Install the package:

make DESTDIR=${CLFS} install

There are some packages that expect to find the lex library in /usr/lib. Create a symlink to account for this:

ln -sv libfl.a ${CLFS}/usr/lib/libl.a

A few programs do not know about flex yet and try to run its predecessor, lex. To support those programs, create a wrapper script named lex that calls flex in lex emulation mode:

cat > ${CLFS}/usr/bin/lex << "EOF"
# Begin /usr/bin/lex

exec /usr/bin/flex -l "$@"

# End /usr/bin/lex
chmod -v 755 ${CLFS}/usr/bin/lex

6.26.2. Contents of Flex

Installed programs: flex and lex
Installed library: libfl.a

Short Descriptions


A tool for generating programs that recognize patterns in text; it allows for the versatility to specify the rules for pattern-finding, eradicating the need to develop a specialized program


A script that runs flex in lex emulation mode


The flex library