# r_bg

0th

Percentile

##### Evaluate an expression in another R session, in the background

Starts evaluating an R function call in a background R process, and returns immediately.

##### Usage
r_bg(func, args = list(), libpath = .libPaths(),
repos = c(getOption("repos"), c(CRAN = "https://cloud.r-project.org")),
stdout = "|", stderr = "|", error = c("error", "stack", "debugger"),
cmdargs = c("--no-site-file", "--no-environ", "--slave", "--no-save",
"--no-restore"), system_profile = FALSE, user_profile = FALSE,
env = rcmd_safe_env())
##### Arguments
func

Function object to call in the new R process. The function should be self-contained and only refer to other functions and use variables explicitly from other packages using the :: notation. The environment of the function is set to .GlobalEnv before passing it to the child process. Because of this, it is good practice to create an anonymous function and pass that to callr, instead of passing a function object from a (base or other) package. In particular

r(.libPaths)


does not work, because .libPaths is defined in a special environment, but

r(function() .libPaths())


works just fine.

args

Arguments to pass to the function. Must be a list.

libpath

The library path.

repos

The repos option. If NULL, then no repos option is set. This options is only used if user_profile or system_profile is set FALSE, as it is set using the system or the user profile.

stdout

The name of the file the standard output of the child R process will be written to. If the child process runs with the --slave option (the default), then the commands are not echoed and will not be shown in the standard output. Also note that you need to call print() explicitly to show the output of the command(s).

stderr

The name of the file the standard error of the child R process will be written to. In particular message() sends output to the standard error. If nothing was sent to the standard error, then this file will be empty. This can be the same file as stderr, although there is no guarantee that the lines will be in the correct chronological order.

error

What to do if the remote process throws an error. See details below.

cmdargs

Command line arguments to pass to the R process. Note that c("-f", rscript) is appended to this, rscript is the name of the script file to run. This contains a call to the supplied function and some error handling code.

system_profile

Whether to use the system profile file.

user_profile

Whether to use the user's profile file.

env

Environment variables to set for the child process.

##### Value

An r_process object, which inherits from process, so all process methods can be called on it, and in addition it also has a get_result() method to collect the result.

• r_bg
##### Examples
# NOT RUN {
rx <- r_bg(function() 1 + 2)

# wait until it is done
rx$wait() rx$is_alive()
rx\$get_result()
# }

Documentation reproduced from package callr, version 2.0.0, License: MIT + file LICENSE

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