Please support --no-dereference

[wez]

From man cp:

       -P, --no-dereference
              never follow symbolic links in SOURCE

The intended outcome is, rather than treating a symlink to a dir as a directory that should be recursively copied, the destination should itself be a symlink with the same target.

Thank you for creating this utility!

[tarka]

Hi @wez, I'm happy to add this, but I'm not sure I understand your underlying issue ATM. By default xcp does not dereference symlinks; in-fact can't, which is a missing feature. Also cp doesn't dereference by default. e.g:

# mkdir source
# cd source/
# echo data > file
# ln -s file file-link
# ln -s /etc/ .
# mkdir dir
# ln -s dir/ dir-link
# cd dir
# ln -s ../file file-link
# cd ../../

# cp -p --recursive --no-dereference source cp-noderef
# cp -p --recursive source cp-default
# xcp --recursive source xcp-default

# tree source/ cp-default/ cp-noderef/ xcp-default/
source/
├── dir
│   └── file-link -> ../file
├── dir-link -> dir/
├── file
└── file-link -> file
cp-default/
├── dir
│   └── file-link -> ../file
├── dir-link -> dir/
├── file
└── file-link -> file
cp-noderef/
├── dir
│   └── file-link -> ../file
├── dir-link -> dir/
├── file
└── file-link -> file
xcp-default/
├── dir
│   └── file-link -> ../file
├── dir-link -> dir/
├── file
└── file-link -> file

I'm missing something here, can you provide a concrete example of a broken and working copy with cp?

Thank you for creating this utility!

You're welcome! I'm glad somebody finds it useful.

[mearsten]

Hi @tarka,

xcp does not dereference symlinks

Yes but no, let me show a case. First do preparations:

% xcp --version
xcp 0.24.2

% mkdir -p 1/some 2; touch 1/some/whatever; ln -s /nix/store/00bc157nm93q5fjz551fwk60ihlbilvj-coreutils-9.7 1

% eza -T .
.
├── 1
│   ├── 00bc157nm93q5fjz551fwk60ihlbilvj-coreutils-9.7 -> /nix/store/00bc157nm93q5fjz551fwk60ihlbilvj-coreutils-9.7
│   └── some
│       └── whatever
└── 2

Then try to copy (with progress bar enabled):

% xcp --recursive --target-directory 2 1/some 1/00bc157nm93q5fjz551fwk60ihlbilvj-coreutils-9.7
[------------------------------------------------------------------------------------------------------]         0 B / 15.48 KiB   |   0% |     0 B/s     | 00:00:00 remaining16:49:39 [ERROR] Error copying: "1/00bc157nm93q5fjz551fwk60ihlbilvj-coreutils-9.7/libexec/coreutils/libstdbuf.so" -> "2/00bc157nm93q5fjz551fwk60ihlbilvj-coreutils-9.7/libexec/coreutils/libstdbuf.so"; aborting.
16:49:39 [ERROR] Received error: Error during copy: Permission denied (os error 13)
Error: Error during copy: Permission denied (os error 13)

% eza -T .
.
├── 1
│   ├── 00bc157nm93q5fjz551fwk60ihlbilvj-coreutils-9.7 -> /nix/store/00bc157nm93q5fjz551fwk60ihlbilvj-coreutils-9.7
│   └── some
│       └── whatever
└── 2
    ├── 00bc157nm93q5fjz551fwk60ihlbilvj-coreutils-9.7 -> /nix/store/00bc157nm93q5fjz551fwk60ihlbilvj-coreutils-9.7
    └── some
        └── whatever

And repeat with no progres bar:

% rm -rf 2; mkdir 2

% xcp --no-progress --recursive --target-directory 2 1/some 1/00bc157nm93q5fjz551fwk60ihlbilvj-coreutils-9.7

% eza -T .
.
├── 1
│   ├── 00bc157nm93q5fjz551fwk60ihlbilvj-coreutils-9.7 -> /nix/store/00bc157nm93q5fjz551fwk60ihlbilvj-coreutils-9.7
│   └── some
│       └── whatever
└── 2
    ├── 00bc157nm93q5fjz551fwk60ihlbilvj-coreutils-9.7
    │   ├── bin
    │   │   ├── [ -> coreutils
    │   │   ├── b2sum -> coreutils
    │   │   ├── base32 -> coreutils
    │   │   ├── base64 -> coreutils
    │   │   ├── basename -> coreutils
    │   │   ├── basenc -> coreutils
…