不跟随符号链接复制文件

Question

像这样在 R 中递归复制文件时：

file.copy(from = "/path/to/sdir", to = "/path/to/dest", recursive=TRUE)

符号链接的目标被复制。我想让 R 按原样复制任何符号而不是它的目标。如果那不可能，我想跳过复制它。

Answer 1

试试 Sys.readlink（感谢@antonio）、file.info（对于 $isdir）和一些相关函数的组合。

copy_dir <- function(src, dest, ..., recursive = TRUE, overwrite = FALSE, mode = "0700") {
 work <- data.frame(
   src = list.files(src, recursive = recursive, full.names = TRUE, include.dirs = TRUE)
 )

 work$link <- Sys.readlink(work$src)
 work$isdir <- file.info(work$src)$isdir

 # if something is both a link and a dir, then remove all children
 srcdirlinks <- work$src[work$isdir & nzchar(work$link)]
 work <- work[rowSums(sapply(srcdirlinks, startsWith, x = work$src)) < 1 |
                work$src %in% srcdirlinks,]

 work$dest <- gsub(paste0("^", src), dest, work$src)

 if (!overwrite) {
   probs <- file.exists(work$dest)
   if (any(probs)) {
     stop("dest files exist, set overwrite=TRUE to force: ",
          paste(sQuote(work$dest[probs]), collapse = ","))
   }
 }

 Vectorize(dir.create)(work$dest[work$isdir & !nzchar(work$link)],
                       recursive = TRUE, mode = mode, showWarnings = FALSE)

 isfile <- !nzchar(work$link) & !work$isdir
 file.copy(work$src[isfile], work$dest[isfile])

 islink <- nzchar(work$link)
 file.symlink(work$link[islink], work$dest[islink])
}

功能证明：

system("find somedir -ls")
#     40135      4 drwxr-xr-x   4 r2       r2           4096 Jul 17 10:14 somedir
#    124826      0 -rw-r--r--   1 r2       r2              0 Jul 17 08:07 somedir/file2
#    124836      0 lrwxrwxrwx   1 r2       r2              5 Jul 17 08:24 somedir/file3s -> file1
#    124825      0 -rw-r--r--   1 r2       r2              0 Jul 17 08:07 somedir/file1
#    124822      0 lrwxrwxrwx   1 r2       r2              4 Jul 17 08:06 somedir/dir3s -> dir1
#    124789      4 drwxr-xr-x   2 r2       r2           4096 Jul 17 08:24 somedir/dir2
#    124824      0 lrwxrwxrwx   1 r2       r2              7 Jul 17 08:24 somedir/dir2/dir21s -> ../dir1
#    124832      0 -rw-r--r--   1 r2       r2              0 Jul 17 08:07 somedir/dir2/file22
#    124833      0 lrwxrwxrwx   1 r2       r2             14 Jul 17 08:23 somedir/dir2/file21s -> ../dir1/file11
#     40136      4 drwxr-xr-x   2 r2       r2           4096 Jul 17 08:23 somedir/dir1
#    124828      0 lrwxrwxrwx   1 r2       r2              6 Jul 17 08:07 somedir/dir1/file12s -> file11
#    124827      0 -rw-r--r--   1 r2       r2              0 Jul 17 08:07 somedir/dir1/file11
copy_dir("somedir", "somedir2", recursive = FALSE)
# [1] TRUE TRUE
system("find somedir2 -ls")
#    124837      4 drwx------   4 r2       r2           4096 Jul 17 10:38 somedir2
#    124841      0 -rw-r--r--   1 r2       r2              0 Jul 17 10:38 somedir2/file2
#    124843      0 lrwxrwxrwx   1 r2       r2              5 Jul 17 10:38 somedir2/file3s -> file1
#    124840      0 -rw-r--r--   1 r2       r2              0 Jul 17 10:38 somedir2/file1
#    124842      0 lrwxrwxrwx   1 r2       r2              4 Jul 17 10:38 somedir2/dir3s -> dir1
#    124839      4 drwx------   2 r2       r2           4096 Jul 17 10:38 somedir2/dir2
#    124838      4 drwx------   2 r2       r2           4096 Jul 17 10:38 somedir2/dir1
unlink("somedir2", recursive = TRUE)
copy_dir("somedir", "somedir2", recursive = TRUE)
# [1] TRUE TRUE TRUE TRUE TRUE
system("find somedir2 -ls")
#    124837      4 drwx------   4 r2       r2           4096 Jul 17 10:38 somedir2
#    124843      0 -rw-r--r--   1 r2       r2              0 Jul 17 10:38 somedir2/file2
#    124851      0 lrwxrwxrwx   1 r2       r2              5 Jul 17 10:38 somedir2/file3s -> file1
#    124842      0 -rw-r--r--   1 r2       r2              0 Jul 17 10:38 somedir2/file1
#    124850      0 lrwxrwxrwx   1 r2       r2              4 Jul 17 10:38 somedir2/dir3s -> dir1
#    124839      4 drwx------   2 r2       r2           4096 Jul 17 10:38 somedir2/dir2
#    124848      0 lrwxrwxrwx   1 r2       r2              7 Jul 17 10:38 somedir2/dir2/dir21s -> ../dir1
#    124841      0 -rw-r--r--   1 r2       r2              0 Jul 17 10:38 somedir2/dir2/file22
#    124849      0 lrwxrwxrwx   1 r2       r2             14 Jul 17 10:38 somedir2/dir2/file21s -> ../dir1/file11
#    124838      4 drwx------   2 r2       r2           4096 Jul 17 10:38 somedir2/dir1
#    124844      0 lrwxrwxrwx   1 r2       r2              6 Jul 17 10:38 somedir2/dir1/file12s -> file11
#    124840      0 -rw-r--r--   1 r2       r2              0 Jul 17 10:38 somedir2/dir1/file11

不跟随符号链接复制文件

Copying files without following symbolic links

filesystems

symlink

r