• Version: 2.5.31
• Summary: Generates fast lexical analyzers, usually used with yacc or bison.

Prerequisites

• GNU m4 macro processor (BuildingGnuMFour)
• GNU Indent (BuildingGnuIndent)

Obtaining

Start by checking http://freshmeat.net/projects/flex/ After a few links, you should be able to find the download page for flex distributions. As of the time of this writing, the current version was 2.5.31

   cd /cis/src/languages
   <... download flex-2.5.31.tar.bz2 ...>
   bzip2 -dc flex-2.5.31.tar.bz2 |tar xf -
   cd flex-2.5.31

Patching 2.5.31

Version 2.5.31 has some problems, it isn't written to standard C in some places. To compile it under a system like Solaris, you'll have to do some light patching (it's easy, though). Hopefully, they'll fix these in the next version of flex.

patch 1 of 3

Make a backup copy of filter.c, then edit it. Look in the =filter_apply_chain_ function, around line 140 you should find two calls to fflush in a row, flushing stdout and stderr. Insert fflush (stdin); just before them, so you have three flushes in a row of stdin, stdout, and stderr.

patch 2 of 3

Then, down around line 161, there are two if statements that attempt to call fdopen and assign its result to stdin and stdout. Ifdef or comment those four lines out.

patch 3 of 3

Finally, around line 187 of the same file, you'll see another if statement that's doing the same thing with fdopen and stdout. Again, comment those two lines out.

Solaris

Ensure the /gnu tree is near the front of all relevant PATH variables in your shell. You can expect three test failure involving bison, if you haven't installed it yet. You can expect one more failure around test-linedir-r if awk isn't gawk. flex installs libraries, so be certain you use the vendor toolkits if installing into /cis.

   PATH=/gnu/bin:${PATH} ; export PATH
   ./configure --prefix=/gnu
   gmake
   gmake check
   gmake install

Documentation

   cd doc; gmake dvi ps pdf; cd ..
   mkdir -m 0775 /gnu/share/doc/flex
   cp [A-Z]* doc/*.dvi doc/*.ps doc/*.pdf /gnu/share/doc/flex