R: Create Names for Temporary Files

tempfile {base} | R Documentation

## 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

`pattern` | a non-empty character vector giving the initial part of the name.
`tmpdir` | a non-empty character vector giving the directory name
`fileext` | a non-empty character vector giving the file extension

### 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 per-session temporary directory found by the following rule when the R session is started. 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. Note that setting any of these environment variables in the R session has no effect on `tempdir()`: the per-session temporary directory is created before the interpreter is started.

### 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 forked by functions 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 try 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

[Package base version 2.15.1 Index]