[Rd] Fwd: Using existing envars in Renviron on friendly Windows

Tomas Kalibera tom@@@k@||ber@ @end|ng |rom gm@||@com
Thu Nov 4 15:24:09 CET 2021 

Thanks for the suggestions, I've updated the documentation.
Tomas

On 11/3/21 11:30 AM, Tomas Kalibera wrote:
>
> On 11/3/21 1:37 AM, Henrik Bengtsson wrote:
>> Oh, I see, I misunderstood.  Thanks for clarifying.
>>
>> One more thing, to mix-and-match environment variables and strings
>> with escaped characters, while mimicking how POSIX shells does it, by
>> using strings with double and single quotes. For example, with:
>>
>> $ cat .Renviron
>> APPDATA='C:\Users\foobar\AppData\Roaming'
>> R_LIBS_USER="${APPDATA}"'\R-library'
>>
>> we get:
>>
>> $ Rscript --no-init-file --quiet -e 'cat(sprintf("R_LIBS_USER=[%s]\n",
>> Sys.getenv("R_LIBS_USER")))'
>> R_LIBS_USER=[C:\Users\foobar\AppData\Roaming\R-library]
>>
>> and
>>
>> $ source .Renviron
>> $ echo "R_LIBS_USER=[${R_LIBS_USER}]"
>> R_LIBS_USER=[C:\Users\foobar\AppData\Roaming\R-library]
> Yes, that could be mentioned explicitly as well.
>
> Tomas
>
>
>>
>> /Henrik
>>
>> On Sun, Oct 31, 2021 at 2:59 AM Tomas Kalibera 
>> <tomas.kalibera using gmail.com> wrote:
>>>
>>> On 10/31/21 2:55 AM, Henrik Bengtsson wrote:
>>>>> ... If one still needed backslashes,
>>>>> they could then be entered in single quotes, e.g. VAR='c:\users'.
>>>> I don't think it matters whether you use single or double quotes -
>>>> both will work.  Here's a proof of concept on Linux with R 4.1.1:
>>>>
>>>> $ cat ./.Renviron
>>>> A=C:\users
>>>> B='C:\users'
>>>> C="C:\users"
>>>>
>>>> $ Rscript -e "Sys.getenv(c('A', 'B', 'C'))"
>>>>             A           B           C
>>>>     "C:users" "C:\\users" "C:\\users"
>>> Yes, but as I wrote "I think the Renviron files should be written in a
>>> way so that they would work the same in a POSIX shell". This is why
>>> single quotes. With double quotes, backslashes are interpreted
>>> differently from a POSIX shell.
>>>
>>> Tomas
>>>
>>>
>>>> /Henrik
>>>>
>>>> On Wed, Oct 27, 2021 at 11:45 AM Tomas Kalibera
>>>> <tomas.kalibera using gmail.com> wrote:
>>>>> On 10/21/21 5:18 PM, Martin Maechler wrote:
>>>>>>>>>>> Michał Bojanowski
>>>>>>>>>>>        on Wed, 20 Oct 2021 16:31:08 +0200 writes:
>>>>>>        > Hello Tomas,
>>>>>>        > Yes, that's accurate although rather terse, which is 
>>>>>> perhaps the
>>>>>>        > reason why I did not realize it applies to my case.
>>>>>>
>>>>>>        > How about adding something in the direction of:
>>>>>>
>>>>>>        > 1. Continuing the cited paragraph with:
>>>>>>        > In particular, on Windows it may be necessary to quote 
>>>>>> references to
>>>>>>        > existing environment variables, especially those 
>>>>>> containing file paths
>>>>>>        > (which include backslashes). For example: `"${WINVAR}"`.
>>>>>>
>>>>>>        > 2. Add an example (not run):
>>>>>>
>>>>>>        > # On Windows do quote references to variables containing 
>>>>>> paths, e.g.:
>>>>>>        > # If APPDATA=C:\Users\foobar\AppData\Roaming
>>>>>>        > # to point to a library tree inside APPDATA in .Renviron 
>>>>>> use
>>>>>>        > R_LIBS_USER="${APPDATA}"/R-library
>>>>>>
>>>>>>        > Incidentally the last example is on backslashes too.
>>>>>>
>>>>>>
>>>>>>        > What do you think?
>>>>>>
>>>>>> I agree that adding an example really helps a lot in such cases,
>>>>>> in my experience, notably if it's precise enough to be used +/- 
>>>>>> directly.
>>>>> Yes, I agree as well. I think the Renviron files should be written 
>>>>> in a
>>>>> way so that they would work the same in a POSIX shell, so e.g.
>>>>> VAR="${VAR0}" or VAR="${VAR0}/subdir" are the recommended ways to
>>>>> preserve backslashes in VAR0. It is better to use forward slashes in
>>>>> string literals, e.g. VAR="c:/users". If one still needed 
>>>>> backslashes,
>>>>> they could then be entered in single quotes, e.g. VAR='c:\users'.
>>>>>
>>>>> The currently implemented parsing of Renviron files differs in a 
>>>>> number
>>>>> of details from POSIX shells, some are documented and some are not.
>>>>> Relying only on the documented behavior that is the same as in POSIX
>>>>> shells is the best choice for future compatibility.
>>>>>
>>>>> Tomas
>>>>>
>>>>>>        > On Mon, Oct 18, 2021 at 5:02 PM Tomas Kalibera 
>>>>>> <tomas.kalibera using gmail.com> wrote:
>>>>>>        >>
>>>>>>        >>
>>>>>>        >> On 10/15/21 6:44 PM, Michał Bojanowski wrote:
>>>>>>        >> > Perhaps a small update to ?.Renviron would be in 
>>>>>> order to mention that...
>>>>>>        >>
>>>>>>        >> Would you have a more specific suggestion how to update 
>>>>>> the
>>>>>>        >> documentation? Please note that it already says
>>>>>>        >>
>>>>>>        >> "‘value’ is then processed in a similar way to a Unix 
>>>>>> shell: in
>>>>>>        >> particular the outermost level of (single or double) 
>>>>>> quotes is stripped,
>>>>>>        >> and backslashes are removed except inside quotes."
>>>>>>        >>
>>>>>>        >> Thanks,
>>>>>>        >> Tomas
>>>>>>        >>
>>>>>>        >> > On Fri, Oct 15, 2021 at 6:43 PM Michał Bojanowski 
>>>>>> <michal2992 using gmail.com> wrote:
>>>>>>        >> >> Indeed quoting works! Kevin suggested the same, but 
>>>>>> he didnt reply to the list.
>>>>>>        >> >> Thank you all!
>>>>>>        >> >> Michal
>>>>>>        >> >>
>>>>>>        >> >> On Fri, Oct 15, 2021 at 6:40 PM Ivan Krylov 
>>>>>> <krylov.r00t using gmail.com> wrote:
>>>>>>        >> >>> Sorry for the noise! I wasn't supposed to send my 
>>>>>> previous message.
>>>>>>        >> >>>
>>>>>>        >> >>> On Fri, 15 Oct 2021 16:44:28 +0200
>>>>>>        >> >>> Michał Bojanowski <michal2992 using gmail.com> wrote:
>>>>>>        >> >>>
>>>>>>        >> >>>> AVAR=${APPDATA}/foo/bar
>>>>>>        >> >>>>
>>>>>>        >> >>>> Which is a documented way of referring to existing 
>>>>>> environment
>>>>>>        >> >>>> variables. Now, with that in R I'm getting:
>>>>>>        >> >>>>
>>>>>>        >> >>>> Sys.getenv("APPDATA")    # That works OK
>>>>>>        >> >>>> [1] "C:\\Users\\mbojanowski\\AppData\\Roaming"
>>>>>>        >> >>>>
>>>>>>        >> >>>> so OK, but:
>>>>>>        >> >>>>
>>>>>>        >> >>>> Sys.getenv("AVAR")
>>>>>>        >> >>>> [1] "C:UsersmbojanowskiAppDataRoaming/foo/bar"
>>>>>>        >> >>> Hmm, a function called by readRenviron does seem to 
>>>>>> remove backslashes,
>>>>>>        >> >>> but not if they are encountered inside quotes:
>>>>>>        >> >>>
>>>>>>        >> >>> 
>>>>>> https://github.com/r-devel/r-svn/blob/3f8b75857fb1397f9f3ceab6c75554e1a5386adc/src/main/Renviron.c#L149
>>>>>>        >> >>>
>>>>>>        >> >>> Would AVAR="${APPDATA}"/foo/bar work?
>>>>>>        >> >>>
>>>>>>        >> >>> --
>>>>>>        >> >>> Best regards,
>>>>>>        >> >>> Ivan
>>>>>>        >> > ______________________________________________
>>>>>>        >> > R-devel using r-project.org mailing list
>>>>>>        >> > https://stat.ethz.ch/mailman/listinfo/r-devel
>>>>>>
>>>>>>        > ______________________________________________
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>>>>> ______________________________________________
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