[Boost-build] How to override variable during install

Subject: [Boost-build] How to override variable during install
From: Avi Bahra (avibahra_at_[hidden])
Date: 2010-05-06 08:46:28

Using  Boost.Jam  Version 3.1.14. OS=LINUX

I want to override the installation directory that was specified via an
environment variable. i.e in my Jamroot.jam

.....
alias install : install-server install-client install-simulator ;
install install-server    : Server//install    : <location>$ECF_INSTALL_DIR
;
install install-client    : Client//install    : <location>$ECF_INSTALL_DIR
;
install install-simulator : Simulator//install : <location>$ECF_INSTALL_DIR
;
explicit install-server ;
explicit install-client ;
explicit install-simulator ;
explicit install ;

This all works OK.   ECF_INSTALL_DIR is an environment variable
   bjam install

However when I do:
    bjam install -s ECF_INSTALL_DIR=$HOME/bin

It ignores the -s, and still uses the environment variable setting.
The documention for -s says:
-s *var*=*value*

Set the variable *var* to *value*, overriding both internal variables and
variables imported from the environment.
have i missed something obvious , as this does not appear to work ?

Any help appreciated.

  Best regards,
Ta,
   Avi