system {base}R Documentation

Invoke a System Command

Description

system invokes the OS command specified by command.

Usage

system(command, intern = FALSE, ignore.stderr = FALSE)

Arguments

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.
ignore.stderr a logical indicating whether error messages (written to `stderr') should be ignored.

Details

If intern is TRUE then popen is used to invoke the command and the output collected, line by line, into an R character vector which is returned as the value of system. Output lines of more that 8096 characters will be split.

If intern is FALSE then the C function system is used to invoke the command and the value returned by system is the exit status of this function.

unix is a deprecated alternative, available for backwards compatibility.

Value

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 an error code.

See Also

.Platform for platform specific variables.

Examples

# list all files in the current directory using the -F flag
system("ls -F")

# t1 is a character vector, each one
# representing a separate line of output from who
t1 <- system("who", TRUE)

system("ls fizzlipuzzli", TRUE, TRUE)# empty since file doesn't exist

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