# sys.source

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##### Parse and Evaluate Expressions from a File

Parses expressions in the given file, and then successively evaluates them in the specified environment.

Keywords
utilities, file
##### Usage
sys.source(file, envir = baseenv(), chdir = FALSE, keep.source = getOption("keep.source.pkgs"))
##### Arguments
file
a character string naming the file to be read from
envir
an R object specifying the environment in which the expressions are to be evaluated. May also be a list or an integer. The default value NULL corresponds to evaluation in the base environment. This is probably not what you want; you should typically supply an explicit envir argument.
chdir
logical; if TRUE, the R working directory is changed to the directory containing file for evaluating.
keep.source
logical. If TRUE, functions keep their source including comments, see options(keep.source = *) for more details.
##### Details

For large files, keep.source = FALSE may save quite a bit of memory.

In order for the code being evaluated to use the correct environment (for example, in global assignments), source code in packages should call topenv(), which will return the namespace, if any, the environment set up by sys.source, or the global environment if a saved image is being used.

source, and library which uses sys.source.
library(base) ## a simple way to put some objects in an environment ## high on the search path tmp <- tempfile() writeLines("aaa <- pi", tmp) env <- attach(NULL, name = "myenv") sys.source(tmp, env) unlink(tmp) search() aaa detach("myenv")