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% Generated by roxygen2: do not edit by hand
% Please edit documentation in R/command.R
\name{bg_process}
\alias{bg_process}
\title{Start a background process}
\usage{
bg_process(command, args = character())
}
\arguments{
\item{command, args}{The system command and its arguments. They do not need to
be quoted, since they will be quoted via \code{\link{shQuote}()}
internally.}
}
\value{
The process ID as a character string.
}
\description{
Start a background process using the PowerShell cmdlet \command{Start-Process
-PassThru} on Windows or the ampersand \command{&} on Unix, and return the
process ID.
}
\details{
If you need to see the output from \verb{stdout} and \verb{stderr}, you may
set \code{options(xfun.bg_process.verbose = TRUE)} before starting the
process. By default, these outputs are hidden.
}
\note{
On Windows, if PowerShell is not available, try to use
\code{\link{system2}(wait = FALSE)} to start the background process
instead. The process ID will be identified from the output of the command
\command{tasklist}. This method of looking for the process ID may not be
reliable. If the search is not successful in 30 seconds, it will throw an
error (timeout). If a longer time is needed, you may set
\code{options(xfun.bg_process.timeout)} to a larger value, but it should be
very rare that a process cannot be started in 30 seconds. When you reach
the timeout, it is more likely that the command actually failed.
}
\seealso{
\code{\link{proc_kill}()} to kill a process.
}
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