Comment author: administrator

Having migrated to OSX I just experienced a problem with
Sys.command. It seems that there is some virual timer working that
expires in some cases. So programs that work usually do not if being
called via Sys.commmand. Example

Sys.command "cd /Users/ap/Unix/sE20;make yacc.cmo";;
/sw/bin/ocamlc -thread -I /Users/ap/Unix/sE20 -I /Users/ap/Unix/sE20/BuiltIn
-I /Users/ap/Unix/sE20/bin -c yacc.ml
make: *** [yacc.cmo] Virtual timer expired

• : int = 2

The virtual timer in question is the one used for time-slicing in the
threads library. Most Unix systems de-activate the timers before doing
exec() of another program (as per the Unix98 spec), but apparently
MacOS X isn't one of these. Hence the timer is still running in the
exec-ed program, causing it to abort.

One workaround is to use Unix.system (in OCaml 3.02 and up) or
ThreadUnix.system (in earlier releases) instead of Sys.command,
because the former deactivate the timer correctly.

Best regards,

• Xavier Leroy

Comment author: administrator

MacOS X doesn't conform to the Unix98 spec w.r.t. interval timers and exec. A
workaround is to use Unix.system rather than Sys.command.