10.16. Flex-2.5.39

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

10.16.1. Installation of Flex

Prepare Flex for compilation:

./configure --prefix=/usr --docdir=/usr/share/doc/flex-2.5.39

Compile the package:


To test the results, issue:

make check

The test suite will report 3 failures for tests that use bison, which is not installed yet. For full test coverage, you can run Flex's test suite again after Bison is installed.

Install the package:

make install

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 > /usr/bin/lex << "EOF"
# Begin /usr/bin/lex

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

# End /usr/bin/lex
chmod -v 755 /usr/bin/lex

10.16.2. Contents of Flex

Installed programs: flex, flex++ (link to flex), lex
Installed libraries: libfl.[a,so], libfl_pic.[a,so]
Installed directory: /usr/share/doc/flex-2.5.39

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


Link to flex which makes it generate C++ scanner classes


A script that runs flex in lex emulation mode


The flex library


The flex library