Hardlink, symlink, or copy a file

Attempt first to make a hardlink. If that fails, try to make a symlink (on non-windows systems and symlink = TRUE). If that fails, copy the file.

linkOrCopy(
  from,
  to,
  symlink = TRUE,
  overwrite = TRUE,
  verbose = getOption("reproducible.verbose", 1)
)

Arguments

from, to

Character vectors, containing file names or paths. to can alternatively be the path to a single existing directory.

symlink

Logical indicating whether to use symlink (instead of hardlink). Default FALSE.

overwrite

Logical. Passed to writeTo (possibly inside postProcess) and postProcess.

verbose

Numeric, -1 silent (where possible), 0 being very quiet, 1 showing more messaging, 2 being more messaging, etc. Default is 1. Above 3 will output much more information about the internals of Caching, which may help diagnose Caching challenges. Can set globally with an option, e.g., options('reproducible.verbose' = 0) to reduce to minimal

Value

This function is called for its side effects, which will be a file.link is that is available or file.copy if not (e.g., the two directories are not on the same physical disk).

Note

Use caution with files-backed objects (e.g., rasters). See examples.

See also

file.link(), file.symlink(), file.copy().

Author

Alex Chubaty and Eliot McIntire

Examples

tmpDir <- file.path(tempdir(), "symlink-test")
tmpDir <- normalizePath(tmpDir, winslash = "/", mustWork = FALSE)
dir.create(tmpDir)

f0 <- file.path(tmpDir, "file0.csv")
write.csv(iris, f0)

d1 <- file.path(tmpDir, "dir1")
dir.create(d1)
write.csv(iris, file.path(d1, "file1.csv"))

d2 <- file.path(tmpDir, "dir2")
dir.create(d2)
f2 <- file.path(tmpDir, "file2.csv")

## create link to a file
linkOrCopy(f0, f2)
#> Hardlinked version of file(s) created:
#> ... no copy/copies made.
#> [1] TRUE
file.exists(f2) ## TRUE
#> [1] TRUE
identical(read.table(f0), read.table(f2)) ## TRUE
#> [1] TRUE

## deleting the link shouldn't delete the original file
unlink(f0)
file.exists(f0) ## FALSE
#> [1] FALSE
file.exists(f2) ## TRUE
#> [1] TRUE

if (requireNamespace("terra", quietly = TRUE)) {
  ## using spatRasters and other file-backed objects
  f3a <- system.file("ex/test.grd", package = "terra")
  f3b <- system.file("ex/test.gri", package = "terra")
  r3a <- terra::rast(f3a)
  f4a <- file.path(tmpDir, "raster4.grd")
  f4b <- file.path(tmpDir, "raster4.gri")
  linkOrCopy(f3a, f4a) ## hardlink
  linkOrCopy(f3b, f4b) ## hardlink
  r4a <- terra::rast(f4a)

  isTRUE(all.equal(r3a, r4a)) # TRUE

  ## cleanup
  unlink(tmpDir, recursive = TRUE)
}
#> Hardlinked version of file(s) created:
#> ... no copy/copies made.
#> Hardlinked version of file(s) created:
#> ... no copy/copies made.