How to Copy Symbolic Link File from Linux to Windows and Then Back to Linux But Still Keeping It as a Symbolic Link

How to copy symbolic link file from Linux to Windows and then back to Linux but still keeping it as a symbolic link

In *nix a symlink is typically just a plain text file with a "symlink" attribute. The file contains the path to the link target. The "symlink" attribute does not exist on Windows. So when you extract the symlink on Windows, it becomes a regular text file [though it may also error, it may depend on a tool you use to extract the archive]. When copied back to *nix, it stays a regular text file.

The only solution would be to keep the "symlink" attribute in some external metadata store and restore the attribute when uploading the file or creating the archive.

Though I'm not aware of any tool that supports this.

You can definitely code this.

1. Using WinSCP: You make a code that generates WinSCP script. The code would recursively iterate a local directory structure. For a file it will generate the put command to upload it. For a symlink it will generate the ln command to create a symlink. To distinguish the symlink, you can maybe use just a simple heuristics (symlink = a short one-line text file with slashes). A proper way would be to remember the file symlink attribute when extracting the archive (but you would have to code the extraction yourself too then, see also a hint below).

2. Using archive:
   I recently implemented this for a ZIP archive. (Even on Windows) You can use the PHP method ZipArchive::setExternalAttributes to flag an archived file as a symlink. Note that the function is available since PHP 5.6 only.

   Sample code:

   $symlink = true; // is symlink?
   $dir = false; // is folder?
   $mode = "755"; // permissions
   
   $local_path = "C:\\zip\\folder\\mylink";
   $zip_path = "folder/mylink";
   
   $attr = 
       (1 << 14) | // this bit seems to be always set
       (1 << ($dir ? 30 : 31)) |
       ($symlink ? (1 << 29) : 0) |
       octdec($mode) << 16;
   
   $zip->addFile($local_path, $zip_path);
   $zip->setExternalAttributesName($zip_path, ZipArchive::OPSYS_UNIX, $attr);
   

   If you are more familiar with Python, see How do I set permissions (attributes) on a file in a ZIP file using Python's zipfile module? It deals with permissions only, but you can easily extend it with the symlink bit, as per my PHP example.

How to convert symlink to regular file?

There is no single command to convert a symlink to a regular file. The most direct way is to use readlink to find the file a symlink points to, and then copy that file over the symlink:

cp --remove-destination `readlink bar.pdf` bar.pdf

Of course, if bar.pdf is, in fact, a regular file to begin with, then this will clobber the file. Some sanity checking would therefore be advisable.

How to copy a directory with symbolic links and resolve them?

cp -rL /source /destination

r = recursive
L = follow and expand symlinks

linux cp: how to have it follow links but not stop if a link target doesn't exist

With the standard GNU toolchain, no, there's no way.

You could instead copy your files, keeping symlinks as symlinks, then use find -follow -type l -delete to delete the broken symlinks, and then copy again, this time following symlinks.

Of course, you could also just write a python etc. program to do the copy for you, or find all files in the original trees that are not broken symlinks and use these with cp, replacing parts of the path with the target path using sed:

find -type d|sed 's/^\(.*\)/"\1" "\/target\/\1"/g'|xargs -p mkdir
find -follow -not -type l -not -type d|sed 's/^\(.*\)/"\1" "\/target\/\1"/g'|xargs -n2 cp

sed will duplicate your found file path, prefixing it with the target directory.

Git symbolic links in Windows

You can find the symlinks by looking for files that have a mode of 120000, possibly with this command:

git ls-files -s | awk '/120000/{print $4}'

Once you replace the links, I would recommend marking them as unchanged with git update-index --assume-unchanged, rather than listing them in .git/info/exclude.

How do I move a relative symbolic link?

You can turn relative paths into full paths using readlink -f foo. So you would do something like:

ln -s $(readlink -f $origlink) $newlink
rm $origlink

EDIT:

I noticed that you wish to keep the paths relative. In this case, after you move the link, you can use symlinks -c to convert the absolute paths back into relative paths.

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