| system {base} | R Documentation |
system invokes the system command specified by command.
system(command, intern=FALSE, wait=TRUE, input,
show.output.on.console=FALSE
invisible=FALSE, minimized=FALSE)
command |
the system command to be invoked, as a string. |
intern |
a logical, indicates whether to make the output of the command an R object. |
wait |
should the R interpreter wait for the command to finish?
The default is to wait, and the interpreter will always wait if
intern = TRUE. |
input |
if a character vector is supplied, this is copied one
string per line to a temporary file, and the standard input of
command is redirected to the file. |
show.output.on.console |
a logical, indicates whether to capture
the output of the command and show it on the R console (not used
by Rterm, which captures the output unless wait
is false). |
invisible |
a logical, indicates whether the command window should be visible on the screen. |
minimized |
a logical, indicates whether the command window should be initially displayed as iconic. |
The command is run directly as a Windows command by the Windows API
call CreateProcess: extensions of .exe, .com,
.cmd and .bat are tried in turn if none
is supplied. (To use DOS internal commands use
command.com /c cmd.) The search path for command
may be system-dependent: it will include the R bin
directory, the working directory and the Windows system directories
before PATH.
Precisely what is seen by the user depends on whether Rgui or
Rterm is being used. For Rgui a new console will
always be used, so a commands window will appear for the duration of
console applications unless invisible is true. For
Rterm a separate commands window
will appear for console applications only if wait=FALSE.
unix is a deprecated alternative, available for
backwards compatibility.
If intern=TRUE, a character vector giving the output of the
command, one line per character string. If the command could not be
run or gives an error a R error is generated.
If intern=FALSE, the return value is a error code, given the
invisible attribute (so needs to be printed explicitly). If the
command could not be run for any reason, the value is -1 and
an R warning is generated. Otherwise if wait=FALSE the value
is the error code returned by the command, and if wait=TRUE
it is the zero (the conventional success value),
If intern=FALSE and show.output.on.console=TRUE
the text output from a command that is a console application will
appear in the R console (Rgui) or the window running R
(Rterm).
The command cannot be interrupted by the R process.
Do not run console applications that require user
input from Rgui setting intern=TRUE and/or
show.output.on.console=TRUE. They will not work,
may hang and then will probably hang Rgui too.
Guido Masarotto and Brian Ripley
shell for a less raw interface.
# launch an editor, wait for it to quit
system("notepad myfile.txt")
# launch a Windows 9x process monitor (from Win9x KernelToys)
system("wintop", wait=FALSE)
# launch your favourite (!) shell:
system("command.com")