system2 invokes the OS command specified by
1 2 3 4
the system command to be invoked, as a character string.
a character vector of arguments to
where output to ‘stdout’ or
‘stderr’ should be sent. Possible values are
should input be diverted?
if a character vector is supplied, this is copied one
string per line to a temporary file, and the standard input of
character vector of name=value strings to set environment variables.
a logical (not
arguments that are accepted on Windows but ignored on this platform, with a warning.
command is always quoted by
shQuote, so it must be a single command without arguments.
For details of how
command is found see
env is only supported for commands such as
make which accept environment variables on
their command line.
Some Unix commands (such as some implementations of
their output if they consider it to be piped or redirected:
stdout = TRUE uses a pipe whereas
"some_file_name" uses redirection.
Because of the way it is implemented, on a Unix-alike
stdout = TRUE: a warning is given if this is
not what was specified.
stdout = TRUE or
stderr = TRUE, a character vector
giving the output of the command, one line per character string.
(Output lines of more than 8095 bytes will be split.) If the command
could not be run an R error is generated. If
command runs but
gives a non-zero exit status this will be reported with a warning and
in the attribute
"status" of the result: an attribute
"errmsg" may also be available.
In other cases, the return value is an error code (
for success), given the invisible attribute (so needs to be printed
explicitly). If the command could not be run for any reason, the
127. Otherwise if
wait = TRUE the value is the
exit status returned by the command, and if
wait = FALSE it is
0 (the conventional success value).
system2 is a more portable and flexible interface than
system, introduced in R 2.12.0. It allows redirection
of output without needing to invoke a shell on Windows, a portable way
to set environment variables for the execution of
finer control over the redirection of
shell on Windows) allows the
invocation of arbitrary command lines.
There is no guarantee that if
stderr are both
TRUE or the same file that the two streams will be interleaved
in order. This depends on both the buffering used by the command and