Hi, I was thinking how to tackle the build failures like the atlas library on OS-X or the ones from xlib and ease the writing of the shell_command a little bit. Dave B did some fancy shell scripting in 'package_emboss_5_0_0' and I was also sometimes forced to use some bash tricks. What about to make that more easy and powerful, and as a plus more consistent with the tool-command tag, and use cheetah for that kind of work. Something like that could work easily: #if ${os.environ}.getVar('X11_LIB_DIR', None): ./configure ... --x-includes=.... #else: ./configure #end if Also we could define some reserved variables like $__is64__ and cheetah evaluate that. $INSTALL_DIR and $REPOSITORY_DIR can also be a cheetah variable and we do not need to replace it later manually. What do you think any comments? If no one has any objections I can try to implement an <action type="cheetah_command">. Thanks, Björn