Ghostscript
Before bitmap() function in Linux, the R system needs Ghostscript software.
R uses ghostscript to translate figure from ps file to other type image file, include jpeg, png and bmp etc.
To download, install and get more information, see
GNU Ghostscript or
ESP Ghostscript.
In Renviron file
Under ${R_HOME}/etc/Renviron, adding a R system environment variable for ghostscript.
If the default "gs" is at "/usr/bin/gs", that Renviron will be
R_GSCMD=${R_GSCMD-'/usr/bin/gs'}
In Script
If no permission to modify Renviron file, you can use the R command "Sys.putenv()" to set up the environment variable.
If the default "gs" is at "/usr/bin/gs", that environment variable can be setted by
