How to copy a folder structure and make symbolic links to files?

Question

I have a folder SOURCE that contains several sub-level folders, each with its own files.

I want to copy this folder in a new folder COPY where I need to copy the directory structure but keep the files as symbolic links to the original files in SOURCE and its subfolders.

Answer 1

Here's the solution on non-embedded Linux and Cygwin:

cp -as SOURCE/ COPY

Note that SOURCE must be an absolute path and have a trailing slash. If you want to give a relative path, you can use

cp -as "$(pwd)/SOURCE/" COPY

Answer 2

There are at least 2 standard utilities to build a shadow directory tree of an existing tree, so no need to write code here.

First there's lndir(1) from the xutils-dev package. It uses symlinks to files. From the man page:

NAME
   lndir  -  create a shadow directory of symbolic links to another
             directory tree
SYNOPSIS
   lndir [ -silent ] [ -ignorelinks ] [ -withrevinfo ] fromdir [ todir ]

A perhaps better alternative is to simply use cp with the right options as the accepted answer suggests. I'll just give some more hopefully useful detail:

cp -al /src/dir /dest/dir    # hard-links to leaf-files
cp -as /src/dir /dest/dir    # symlinks to leaf-files

If you don't care about preserving all attributes (ownerships/permissions, times) replace the a option (equivalent to -dr --preserve=all) with r (recursive only):

cp -rl /src/dir /dest/dir    # hard-links to leaf-files
cp -rs /src/dir /dest/dir    # symlinks to leaf-files

Answer 3

You can try a couple of find commands like this:

mkdir FULL-PATH-TO-COPY
cd SOURCE
find . \( ! -regex '\.' \) -type d -exec mkdir FULL-PATH-TO-COPY/{} \;
find * -type f -exec ln -s `pwd`/{} FULL-PATH-TO-COPY/{} \;

Answer 4

GNU shtool provides such a feature:

shtool mkshadow srcdir destdir

Moreover, if your point is to make a shallow copy of a source directory into a build tree, you can distribute shtool with your source tree as it is a portable shell script (which provides many other facilities you might be interested in).

Answer 5

Something like this POSIX script will do what you need.

#!/bin/sh
#
SOURCE="$1" COPY="$2"
cd "$SOURCE"
find . |
    sed 's!^\./!!' |
    while IFS= read -r ITEM
    do
        if test -d "$ITEM"
        then
            mkdir -p "$COPY/$ITEM"
            continue
        fi
        BASE="${FILE%\/*}"
        ( cd "$COPY/$BASE" && ln -s "$SOURCE/$ITEM" )
    done

Directories are created in the target COPY tree. Everything else is symlinked back to the absolute path within the SOURCE tree. Ensure that both SOURCE and COPY are specified as absolute paths (starting with /).

If you have a large tree to copy and you want a per-directory progress report, you could add echo "$ITEM" >&2; just before the mkdir command.

(I looked at POSIX cp and cpio but neither seems to have an option for linking to the source with symbolic links.)

Answer 6

If there are not empty dirs in SOURCE which need to be copied

find /full/path/to/SOURCE -type f -exec cp -t COPY --parents -s {} +
mv COPY/full/path/to/SOURCE COPY
rm -r COPY/full

Answer 7

I would start by breaking out the perl:

#!/usr/bin/perl

use strict;
use warnings;
use File::Find;

my $src_dir = "/full_path/to/dir";
my $tgt_dir = "/path/to/new/location";

sub link_or_mkdir {

    #current file is directory
    if (-d) {
        #extract the path
        my $newpath = $File::Find::dir;
        #change the path so 'old' and 'new' are swapped
        $newpath =~ s,^$src_dir,$tgt_dir,g;
        #print the command to make a new dir (doesn't actually do it)
        print "mkdir -p $newpath\n";
    }
    if (-f) {
        my $new_file = $File::Find::name;
        #change the path so 'old' and 'new' are swapped
        $new_file =~ s,^$src_dir,$tgt_dir,g;
        #print the symlink command
        print "ln -s $File::Find::name $new_file\n";
    }
}

find( \&link_or_mkdir, $tgt_dir );

File::Find is a useful module that allows you to run a specific subroutine on any file within a directory tree. In this case, the sub checks if it's a directory - and if it is, does a mkdir or a file - in which case it does a symlink.

Answer 8

It seems you are looking for something like the tool rsnapshot; it creates copies of arbitrary directories and uses hardlinks where possible. (Have a look at the man page to see whether that fits.)