rshellerror-handlingsystemsystem2

R system functions always returns error 127

I need to execute an external tool from R and process errors (if any) occurred in that tool. I know 3 functions to do something familiar with my task: 

shell, system and system2.

Trying to test those, I see that command 

shell("notepad")

opens notepad. As far as I know shell doesn't allow to check errors (there's no interface to look into stderr).

When I call 

system("notepad")

or 

system2("notepad")

R freezes trying to make those commands.

Calling 

system("start notepad")

or 

system2("start notepad")

returns warning 

Warning message:
running command '"start notepad"' had status 127
Solution

  • As I mentioned in my comments, the R documentation reveals that in Windows the system() function does not launch a separate shell (if needed). This is why command line commands run with system(), but Notepad, which needs a separate window, does not run:

    From the documentation for system():

    The most important difference is that on a Unix-alike system launches a shell which then runs command. On Windows the command is run directly – use shell for an interface which runs command via a shell (by default the Windows shell cmd.exe, which has many differences from a POSIX shell).