[R] unable to start device JPEG in linux

[Haiyan Pan]

r-help£¬
 When I want to use jpeg() in R-2.1.1 which is installed in linux platform to generate a jpeg file, the error occurs as following:
 
 > jpeg()
Error in X11(paste("jpeg::", quality, ":", filename, sep = ""), width,  : 
        unable to start device JPEG
In addition: Warning message:
unable to open connection to X11 display '' 
> capabilities()  
    jpeg      png    tcltk      X11 http/ftp  sockets   libxml     fifo 
   FALSE    FALSE     TRUE    FALSE     TRUE     TRUE     TRUE     TRUE 
  cledit  IEEE754    iconv 
    TRUE     TRUE     TRUE 

X11 device is existed in this machine, would you suggest me how to resolve this problem. 
Many thanks for your help and it will be greatly appreciated!
	


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 Haiyan Pan
 hypan at scbit.org

 Tel: 021-64363311-123
 Shanghai Center for Bioinformatics Technology
 Floor 12th,100# QinZhou Road
 Shanghai,China,200235