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

From: Prof Brian Ripley <ripley_at_stats.ox.ac.uk>
Date: Mon 15 Jan 2007 - 14:13:28 GMT

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@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

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Received on Tue Jan 16 01:18:58 2007

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