.libPaths(new)
base::.Library
base::.Library.site

If you supply a value for new:

• Character strings specified by new are passed through normalizePath to convert relative paths to absolute paths, and to convert a possible initial tilde to the user's home directory.
• The package search path is changed to unique(c(new, base::.Library.site, base::.Library)).
• The new list of library directories is returned from the function.
• If new refers to an invalid path, the argument is ignored.

If you do not supply a value for new, then the search path does not change, and .libPaths() just returns the current list of library directories.

.Library is a character string specifying the path of the default library (R.home("library")).

.Library.site is a character vector specifying the locations of site-specific libraries. Its default value, set when Spotfire Enterprise Runtime for R (TERR) starts a session, is R.home("site-library"), but you can override it before you start TERR by setting the environment variable TERR_LIBS_SITE to a colon-separated (on Linux) or semicolon-separated (on Windows) list of directories. Directories that do not exist at startup time are silently omitted from .Library.site.

Neither .Library nor .Library.site can be changed after a TERR session starts.

When TERR starts a session, it uses the values of Sys.getenv("TERR_LIBS") and Sys.getenv("TERR_LIBS_USER") (treated as colon-separated or semicolon-separated lists of directories) in a call to .libPaths(). TERR_LIBS_USER should be considered a user-specific list of libraries for the current platform and version of TERR, and it has the default value .expand_R_libs_env_var("\~/TERR/%p-library/%v"). TERR_LIBS should be considered as a session-specific list of libraries, and it has no default value.

# list libraries.
.libPaths()
# add "~/packages" to front of list of libraries, if it names a directory.
.libPaths(c("~/packages", .libPaths()))