[R] Problem with pdf, png, jpeg devices and files named CON on Window s

[Prof Brian Ripley]

This is a restriction of the ISO C interface to the Windows API.  E.g. 
'check' says

     ## Furthermore, Uwe Ligges says that Windows still does not allow
     ## the following DOS device names (by themselves or with possible
     ## extensions):
     ##
     ## Name    Function
     ## ----    --------
     ## CON     Keyboard and display
     ## PRN     System list device, usually a parallel port
     ## AUX     Auxiliary device, usually a serial port
     ## CLOCK$  System real-time clock
     ## NUL     Bit-bucket device
     ## COM1    First serial communications port
     ## COM2    Second serial communications port
     ## COM3    Third serial communications port
     ## COM4    Fourth serial communications port
     ## LPT1    First parallel printer port
     ## LPT2    Second parallel printer port
     ## LPT3    Third parallel printer port

Windows Explorer seems to have a different set of rules, disallowing a lot 
of valid names (e.g. .Rprofile) but allowing some invalid ones.

On Mon, 15 Jan 2007, Brandt, T. (Tobias) wrote:

> Hi
>
> I cannot seem to create any files that have the name "CON" before the file
> extension, i.e. all of the following fail:
>
>> pdf("CON.pdf")
> Error in pdf("CON.pdf") : unable to start device pdf
>> jpeg('CON.jpeg')
> Error in jpeg("CON.jpeg") : unable to start device devWindows
>> png('CON.png')
> Error in png("CON.png") : unable to start device devWindows
>> sink('CON.txt')
> Error in file(file, ifelse(append, "a", "w")) :
>        unable to open connection
>>
>
> Any filename other than this works fine.
>
>> png('ICON.png')
>> dev.off()
> null device
>          1
>> png('CON1.png')
>> dev.off()
> null device
>          1
>> sink('log.txt')
>> sink()
>>
>
> Remembering that in the old DOS days, commands like 'copy CON myfile.bat'
> were common, I suspected that this has something to do with CON being a
> reserved word so I tried to create the files manually in Windows explorer.
> Creating files named 'CON.png', 'CON.pdf', 'CON.txt' all work fine. However
> I did notice that Windows won't let me create a file named just "CON".
> However since the devices that I'm trying to create have extensions, I don't
> understand why they fail.
>
> Who can help?
>
> Thanks
> Tobias
>
>
>> version
>               _
> platform       i386-pc-mingw32
> arch           i386
> os             mingw32
> system         i386, mingw32
> status
> major          2
> minor          3.1
> year           2006
> month          06
> day            01
> svn rev        38247
> language       R
> version.string Version 2.3.1 (2006-06-01)
>>
>
>> Sys.info()
>                      sysname                       release
> version                      nodename
>                    "Windows"                      "NT 5.1" "(build 2600)
> Service Pack 2"
>                      machine                         login
> user
>                        "x86"
>>
>
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-- 
Brian D. Ripley,                  ripley at stats.ox.ac.uk
Professor of Applied Statistics,  http://www.stats.ox.ac.uk/~ripley/
University of Oxford,             Tel:  +44 1865 272861 (self)
1 South Parks Road,                     +44 1865 272866 (PA)
Oxford OX1 3TG, UK                Fax:  +44 1865 272595