Installing Flex-2.5.4a

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

Approximate build time:  0.1 SBU
Required disk space:     3.4 MB

Official download location for Flex (2.5.4a): 
ftp://ftp.gnu.org/gnu/non-gnu/flex/

For its installation Flex depends on: Bash, Binutils, Bison, Coreutils, Diffutils, GCC, Gettext, Glibc, Grep, M4, Make, Sed.

Installation of Flex

Prepare Flex for compilation:

./configure --prefix=/usr

Compile the package:

make

This package has a test suite available which can perform a number of checks to ensure it built correctly. Should you choose to run it, the following command will do so:

make bigcheck

And install the package:

make install

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

ln -s libfl.a /usr/lib/libl.a

A few programs don't know about flex yet and try to run its predecessor lex. To support those programs, create a shell script named lex that calls flex in Lex emulation mode:

cat > /usr/bin/lex << "EOF"
#!/bin/sh
# Begin /usr/bin/lex

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

# End /usr/bin/lex
EOF
chmod 755 /usr/bin/lex

Contents of Flex

Installed programs: flex, flex++ (link to flex) and lex

Installed library: libfl.a

Short descriptions

flex is a tool for generating programs that recognize patterns in text. Pattern recognition is useful in many applications. From a set of rules on what to look for flex makes a program that looks for those patterns. The reason to use flex is that it is much easier to specify the rules for than to write the actual pattern-finding program.

flex++ invokes a version of flex that is used exclusively for C++ scanners.

libfl.a is the flex library.