Copying with symlinks dereferenced is almost always the case for me, because of the version control system we use. It is a central VCS. So we need to check out the files before editing them. In checked-in state, all files are just symlinks to the physical versions in a central cache server. So almost always "cp -L" is what I want to do when copying files from one place to another without checking them out. My cp is aliased to "cp -L".
That said, here's the revised patch with updated documentation and "Revisited Option 1" I mentioned above. This allows the flexibility of *not* dereferencing symlinks for few selected cases when I would have set dired-copy-dereference to t by default in my config.
From 28b9a7c41c168daec6645638c06d5333e8b642aa Mon Sep 17 00:00:00 2001
Date: Wed, 30 Nov 2016 12:52:42 -0500
Subject: [PATCH] Dired can now dereference symlinks when copying
* lisp/dired.el (dired-copy-dereference): New defcustom, defaults to
nil.
* lisp/dired-aux.el (dired-copy-file-recursive): Add new optional
argument `dereference'.
* lisp/dired-aux.el (dired-copy-file): Use `dired-copy-dereference' as
the `dereference' argument to `dired-copy-file-recursive'.
* lisp/dired-aux.el (dired-do-copy): Invert the value of
`dired-copy-dereference' in lexical scope when prefix argument is
'(4). Update function documentation for the new defcustom.
* doc/emacs/dired.texi (Operating on Files): Mention the new defcustom.
---
doc/emacs/dired.texi | 8 ++++++++
lisp/dired-aux.el | 25 +++++++++++++++++++------
lisp/dired.el | 6 ++++++
3 files changed, 33 insertions(+), 6 deletions(-)
diff --git a/doc/emacs/dired.texi b/doc/emacs/dired.texi
index 2cda51a82f..62042c5c1e 100644
--- a/doc/emacs/dired.texi
+++ b/doc/emacs/dired.texi
@@ -638,6 +638,14 @@ Operating on Files
directories recursively (like @samp{cp -r}). The default is
@code{top}, which means to ask before recursively copying a directory.
+@vindex dired-copy-dereference
+@cindex follow symbolic links
+@cindex dereference symbolic links
+The variable @code{dired-copy-dereference} controls whether to copy
+symbolic links as links or after dereferencing (like @samp{cp -L}).
+The default is @code{nil}, which means that the symbolic links are
+copied by creating new ones.
+
@item D
@findex dired-do-delete
@kindex D @r{(Dired)}
diff --git a/lisp/dired-aux.el b/lisp/dired-aux.el
index f94e0537aa..1b9009c744 100644
--- a/lisp/dired-aux.el
+++ b/lisp/dired-aux.el
@@ -1507,12 +1507,13 @@ dired-handle-overwrite
(defun dired-copy-file (from to ok-flag)
(dired-handle-overwrite to)
(dired-copy-file-recursive from to ok-flag dired-copy-preserve-time t
- dired-recursive-copies))
+ dired-recursive-copies dired-copy-dereference))
(declare-function make-symbolic-link "fileio.c")
(defun dired-copy-file-recursive (from to ok-flag &optional
- preserve-time top recursive)
+ preserve-time top recursive
+ dereference)
(when (and (eq t (car (file-attributes from)))
(file-in-directory-p to from))
(error "Cannot copy `%s' into its subdirectory `%s'" from to))
@@ -1524,7 +1525,8 @@ dired-copy-file-recursive
(copy-directory from to preserve-time)
(or top (dired-handle-overwrite to))
(condition-case err
- (if (stringp (car attrs))
+ (if (and (not dereference)
+ (stringp (car attrs)))
;; It is a symlink
(make-symbolic-link (car attrs) to ok-flag)
(copy-file from to ok-flag preserve-time))
@@ -1963,6 +1965,9 @@ dired-copy-how-to-fn
;;;###autoload
(defun dired-do-copy (&optional arg)
"Copy all marked (or next ARG) files, or copy the current file.
+ARG has to be numeric for above functionality. See
+`dired-get-marked-files' for more details.
+
When operating on just the current file, prompt for the new name.
When operating on multiple or marked files, prompt for a target
@@ -1976,10 +1981,18 @@ dired-do-copy
the modification time of each old file in the copy, similar to
the \"-p\" option for the \"cp\" shell command.
-This command copies symbolic links by creating new ones, similar
-to the \"-d\" option for the \"cp\" shell command."
+This command copies symbolic links by creating new ones,
+similar to the \"-d\" option for the \"cp\" shell command.
+But if `dired-copy-dereference' is non-nil, the symbolic
+links are dereferenced and then copied, similar to the \"-L\"
+option for the \"cp\" shell command. If ARG is a cons with
+element 4 (`\\[universal-argument]'), inverted value of
+`dired-copy-dereference' will be used."
(interactive "P")
- (let ((dired-recursive-copies dired-recursive-copies))
+ (let ((dired-recursive-copies dired-recursive-copies)
+ (dired-copy-dereference (if (equal arg '(4))
+ (not dired-copy-dereference)
+ dired-copy-dereference)))
(dired-do-create-files 'copy (function dired-copy-file)
"Copy"
arg dired-keep-marker-copy
diff --git a/lisp/dired.el b/lisp/dired.el
index daa6d776a9..ca7ab2813b 100644
--- a/lisp/dired.el
+++ b/lisp/dired.el
@@ -191,6 +191,12 @@ dired-copy-preserve-time
:type 'boolean
:group 'dired)
+(defcustom dired-copy-dereference nil
+ "If non-nil, Dired dereferences symlinks when copying them.
+This is similar to the \"-L\" option for the \"cp\" shell command."
+ :type 'boolean
+ :group 'dired)
+ ;
; These variables were deleted and the replacements are on files.el.
; We leave aliases behind for back-compatibility.
(defvaralias 'dired-free-space-program 'directory-free-space-program)
--
2.11.0