http://gcc.gnu.org/bugzilla/show_bug.cgi?id=30090
--- Comment #2 from Dmitry Gorbachev <d.g.gorbachev at gmail dot com> 2011-01-30 23:39:27 UTC --- $ gcc --version gcc (GCC) 4.6.0 20110129 (experimental) Copyright (C) 2011 Free Software Foundation, Inc. This is free software; see the source for copying conditions. There is NO warranty; not even for MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. $ grep -A6 'Specs are strings' gcc-4.6/gcc/gcc.c Specs are strings containing lines, each of which (if not blank) is made up of a program name, and arguments separated by spaces. The program name must be exact and start from root, since no path is searched and it is unreliable to depend on the current working directory. Redirection of input or output is not supported; the subprograms must accept filenames saying what files to read and write. $ gcc -E -x foo_language -specs=specs /dev/null /usr/local/sbin:/usr/local/bin:/usr/sbin:/usr/bin:/sbin:/bin:/usr/games /usr/games/fortune Never reveal your best argument.