[jamming] BJam's command/shell execution

[Joshua ChaitinPollak]

Hi,

I'm using BJam, and I can't figure out how to get the shell script  
execution working. I know there was a recent thread about a COMMAND  
patch for Jam, and I'm looking forward to that, but for now I'm using  
BJam and I don't have the time to apply patches and compile, etc.

I've ported most of my project to Jam, but I have one Makefile I  
can't figure out how to ditch. I have this Makefile code:

REVISION := $(shell svnversion)
OLD_REVISION := $(shell cat revision.cpp 2> /dev/null)

revision.cpp:
ifeq (,$(findstring \"{REVISION}\", ${OLD_REVISION}))
   @echo "void config::getRevision(std::string& rev) { rev = \"$ 
{REVISION}\"; } >> revision.cpp
endif

This (should) effectively (re)builds revision.cpp if the revision has  
changed. My program depends in revision.cpp, so if revision has  
changed, the file gets rebuild and the program gets rebuilt.

How would I do this in a Jam way? I guess I could call a shell script  
to build the revision.cpp file all the time, but I'd rather not  
unless its out of date.

-Josh

-- 
Joshua ChaitinPollak
Software Engineer
Kiva Systems