Re: Handling of shell builtins in make(1)

From: Harti Brandt (hartmut.brandt_at_dlr.de)
Date: 05/24/05

  • Next message: Sergey Babkin: "Re: Re: Handling of shell builtins in make(1)" 
    Date: Tue, 24 May 2005 12:46:33 +0200 (CEST)
To: Peter Jeremy <PeterJeremy@optushome.com.au>

    On Tue, 24 May 2005, Peter Jeremy wrote:

    PJ>On Mon, 2005-May-23 20:50:40 -0600, Scott Long wrote:
    PJ>>Harti Brandt wrote:
    PJ>>>The result of this is that for one and the same command you can get
    PJ>>>different behaviour whether you execute it via make(1) or via sh -c '...'.
    PJ>
    PJ>Not to mention the effect of IFS. Does POSIX provide any helpful
    PJ>suggestions on how to efficiently implement the behaviour they specify?

    POSIX has no .SHELL target - that's pmake's invention. IFS is no problem
    because in order to specify a different IFS you need to have at least a
    '=' on the command line. This is a meta character so the command will be
    executed by the shell.

    Generally POSIX says that make should execute command lines as if given to
    system(). System() in turn says that it should behave as if it fork()ed
    and execl()ed "sh -c ...". The as-if here seems to allow for our
    optimisation.

     PJ>
    PJ>>4. Separate /bin/sh into a front end and back end (libsh) and include
    PJ>>libsh into make.
    PJ>
    PJ>And this still won't help people who use .SHELL (or similar) to pick
    PJ>a different shell.
    PJ>
    PJ>5) Add a "POSIX_ME_HARDER" option that just invokes the shell on every
    PJ> command. In the absence of this option, make(1) is free to directly
    PJ> exec the command if it's simple enough.
    PJ>
    PJ>6) Add two new magic line markers (to supplement '@', '+' and '-') to
    PJ> require the line be executed using the shell or exec'd directly,
    PJ> superceding the buildin rules.

    You can alway make to execute the shell by putting a meta-character on the
    command line or by specifying and empty builtin list or an empty meta
    character list to .SHELL. But what should we do as default?

    harti
    _______________________________________________
    freebsd-arch@freebsd.org mailing list
    http://lists.freebsd.org/mailman/listinfo/freebsd-arch
    To unsubscribe, send any mail to "freebsd-arch-unsubscribe@freebsd.org"

  • Next message: Sergey Babkin: "Re: Re: Handling of shell builtins in make(1)"

    Relevant Pages