CPPFLAGS=-Dre_max_failures=re_max_failures2: The CPPFLAGS variable is a variable that's read by the cpp program (C PreProcessor). The value of this variable tells the preprocessor to replace every instance of re_max_failures it finds by re_max_failures2 before handing the source file to the compiler itself for compilation. This package has problems linking statically on systems that run an older Glibc version and this construction fixes that problem. PR_PROGRAM=/usr/bin/pr: When 'diff' is called with the '-l' flag, it tries to find 'pr' at the location specified with the PR_PROGRAM variable. By default, this variable points to '/bin/pr', but since we install 'pr' in /usr/bin, we need to change this.