Regex provides an implementation of the GNU, POSIX, and BSD regular expression functions. Current versions are derived from the GNULIB implementation of the regex module, but an older version of the runtime derived from the venerable GNU regex library, with a slightly different interface, is available for legacy MSYS applications. The msys-regex package provides the documentation for the regex library, while the associated msys-libregex package provides the runtime library and related development files. Regex provides an implementation of the GNU, POSIX, and BSD regular expression functions. Current versions are derived from the GNULIB implementation of the regex module, but an older version of the runtime derived from the venerable GNU regex library, with a slightly different interface, is available for legacy MSYS applications. The msys-libregex package the runtime library and related development files, while the associated msys-regex package provides the documentation.