peter dalgaard <pda...@gmail.com> writes: > On 29 Oct 2015, at 10:44 , Rainer M Krug <rai...@krugs.de> wrote: > >> Out of interest: What is the magic ~R CMD~ is doing? Is it documented >> anywhere? > > > R is open source.... (and shell scripts are considered self-documenting by > some)
True - should have looked in the sources...
>
> On Unix-alikes, R is a shell script which, if called with 1st argument
> CMD, calls ${R_HOME}/bin/Rcmd, which is another shell script that ends
> with
>
> case "${1}" in
> ## this was a separate command prior to 2.10.0
> Rd2txt)
> cmd="${R_HOME}/bin/Rdconv"
> extra="-t txt"
> ;;
> ## removed in 2.15.0
> Rd2dvi)
> echo "R CMD Rd2dvi is defunct: use Rd2pdf instead"
> exit 1
> ;;
> *)
> if test -x "${R_HOME}/bin/${1}"; then
> cmd="${R_HOME}/bin/${1}"
> else
> cmd="${1}"
> fi
> ;;
> esac
> shift
>
> exec "${cmd}" ${extra} "${@}"
>
> I.e., except for setting up variables and such, R CMD ${foo}
> essentially looks for ${R_HOME}/bin/${foo} and executes it if it
> exists and is executable, otherwise it just executes ${foo}.
Thanks for that detailed explanation of the mechanism - it is much
clearer now. And as usual, if one knows how something is happening, it's
not "magical" anymore.
>
> Notice that, somewhat contrary to what Dirk said, this logic works at
> the mercy of the file system when it comes to case sensitivity. On OSX
> with the default case-insensitive setup we get
>
> Peters-iMac:IBP pd$ R CMD install
> Error: ERROR: no packages specified
>
> which comes from R's package installer, whereas a case-sensitive FS
> would pick up /usr/bin/install instead. That is just how the "test"
> shell built-in works:
>
> Peters-iMac:~ pd$ test -x `R RHOME`/bin/INSTALL ; echo $?
> 0
> Peters-iMac:~ pd$ test -x `R RHOME`/bin/UNSTALL ; echo $?
> 1
> Peters-iMac:~ pd$ test -x `R RHOME`/bin/install ; echo $?
> 0
Yeah - true. I was already starting to wonder as I always was using ~R
CMD install~ and it always worked on my Mac.
Thanks again,
Rainer
--
Rainer M. Krug, PhD (Conservation Ecology, SUN), MSc (Conservation Biology,
UCT), Dipl. Phys. (Germany)
Centre of Excellence for Invasion Biology
Stellenbosch University
South Africa
Tel : +33 - (0)9 53 10 27 44
Cell: +33 - (0)6 85 62 59 98
Fax : +33 - (0)9 58 10 27 44
Fax (D): +49 - (0)3 21 21 25 22 44
email: rai...@krugs.de
Skype: RMkrug
PGP: 0x0F52F982
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