Create Names for Temporary Files

Description

tempfile returns a vector of character strings which can be used as names for temporary files.

Usage

tempfile(pattern = "file", tmpdir = tempdir(), fileext = "")
tempdir()

Arguments

Details

The length of the result is the maximum of the lengths of the three arguments; values of shorter arguments are recycled.

The names are very likely to be unique among calls to tempfile in an R session and across simultaneous R sessions (unless tmpdir is specified). The filenames are guaranteed not to be currently in use.

The file name is made by concatenating the path given by tmpdir, the pattern string, a random string in hex, and a suffix of fileext.

By default, tmpdir will be the directory given by tempdir(). This will be a subdirectory of the temporary directory found by the following rule. The environment variables TMPDIR, TMP and TEMP are checked in turn and the first found which points to a writable directory is used: if none succeeds ‘/tmp’ is used.

Value

For tempfile a character vector giving the names of possible (temporary) files. Note that no files are generated by tempfile.

For tempdir, the path of the per-session temporary directory.

Note on parallel

R processes produced by function such as mclapply in package parallel (or multicore) share a per-session temporary directory. Further, the ‘guaranteed not to be currently in use’ applies only at the time of asking, and two children could ask simultaneously. As from R 2.14.1 this is avoided by ensuring that tempfile calls in different children look for different names.

References

Becker, R. A., Chambers, J. M. and Wilks, A. R. (1988) The New S Language. Wadsworth & Brooks/Cole.

See Also

unlink for deleting files.

Examples

tempfile(c("ab", "a b c"))   # give file name with spaces in!

tempfile("plot", fileext=c(".ps", ".pdf"))

tempdir() # works on all platforms with a platform-dependent result