Dired: group directories and symlinks to directories first

Question

Is there a way to make dired group directories and symlinks to directories first?

If I add --group-directories, like this:

(setq dired-listing-switches "--group-directories-first -al")

then it groups directories first, but symlinks still get sorted under files.

If I also add --dereference, like:

(setq dired-listing-switches "--group-directories-first --dereference -al")

then symlinks get resolved, and the directories do all show up together. But there's no indication anymore that they are symlinks anymore. I'd like them to be still displayed as symlinks, but get grouped first too.

Answer 1

Yes, that is what you get if you load standard library ls-lisp.el and you customize option ls-lisp-dirs-first to non-nil.

(If the value of option ls-lisp-emulation is MS-Windows then ls-lisp-dirs-first is non-nil by default. This is the case if you use Emacs on MS Windows, but you can set it this way on any platform.)

If you also use library Dired Sort Menu then you get a S-mouse-2 popup menu in Dired (and a menu-bar menu) that provides all of the ls-lisp.el sorting possibilities.

Answer 2

The ls-lisp solution is portable and straightforward, but unfortunately lacks some important (to me) flags and is considerably slower.

So instead, one can also modify ls directly. Because I wanted the same feature in ls in the terminal anyway, I wrote a patch for the ls in GNU's coreutils. That's certainly a lot less portable, but it was a much smaller and more desirable change than extending ls-lisp with the missing flags. (Still, ls-lisp can be used as a fallback as well.)

This patch for coreutils (8.25) sorts symlinked directories like directories when --group-directories-first is provided:

diff --git a/src/ls.c b/src/ls.c
index 3572060..8dd6395 100644
--- a/src/ls.c
+++ b/src/ls.c
@@ -2969,10 +2969,10 @@ gobble_file (char const *name, enum filetype type, ino_t inode,
               || is_colored (C_STICKY_OTHER_WRITABLE)))
       /* When dereferencing symlinks, the inode and type must come from
          stat, but readdir provides the inode and type of lstat.  */
-      || ((print_inode || format_needs_type)
+      || ((print_inode || format_needs_type || directories_first)
           && (type == symbolic_link || type == unknown)
           && (dereference == DEREF_ALWAYS
-              || color_symlink_as_referent || check_symlink_color))
+              || color_symlink_as_referent || check_symlink_color || directories_first))
       /* Command line dereferences are already taken care of by the above
          assertion that the inode number is not yet known.  */
       || (print_inode && inode == NOT_AN_INODE_NUMBER)
@@ -3113,7 +3113,7 @@ gobble_file (char const *name, enum filetype type, ino_t inode,
         }

       if (S_ISLNK (f->stat.st_mode)
-          && (format == long_format || check_symlink_color))
+          && (format == long_format || check_symlink_color || directories_first))
         {
           struct stat linkstats;

@@ -3123,7 +3123,7 @@ gobble_file (char const *name, enum filetype type, ino_t inode,
           /* Avoid following symbolic links when possible, ie, when
              they won't be traced and when no indicator is needed.  */
           if (linkname
-              && (file_type <= indicator_style || check_symlink_color)
+              && (file_type <= indicator_style || check_symlink_color || directories_first)
               && stat (linkname, &linkstats) == 0)
             {
               f->linkok = true;
@@ -3131,7 +3131,7 @@ gobble_file (char const *name, enum filetype type, ino_t inode,
               /* Symbolic links to directories that are mentioned on the
                  command line are automatically traced if not being
                  listed as files.  */
-              if (!command_line_arg || format == long_format
+              if (!command_line_arg || format == long_format || directories_first
                   || !S_ISDIR (linkstats.st_mode))
                 {
                   /* Get the linked-to file's mode for the filetype indicator
@@ -3251,6 +3251,15 @@ is_directory (const struct fileinfo *f)
   return f->filetype == directory || f->filetype == arg_directory;
 }

+/* Return true if F refers to a directory or a symlink pointing at a directory.  */
+static bool
+is_directory_or_symlink_to_directory (const struct fileinfo *f)
+{
+  return f->filetype == directory
+    || f->filetype == arg_directory
+    || (f->filetype == symbolic_link && S_ISDIR(f->linkmode));
+}
+
 /* Put the name of the file that FILENAME is a symbolic link to
    into the LINKNAME field of 'f'.  COMMAND_LINE_ARG indicates whether
    FILENAME is a command-line argument.  */
@@ -3396,8 +3405,8 @@ typedef int (*qsortFunc)(V a, V b);
 #define DIRFIRST_CHECK(a, b)                       \
   do                                   \
     {                                  \
-      bool a_is_dir = is_directory ((struct fileinfo const *) a);  \
-      bool b_is_dir = is_directory ((struct fileinfo const *) b);  \
+      bool a_is_dir = is_directory_or_symlink_to_directory ((struct fileinfo const *) a); \
+      bool b_is_dir = is_directory_or_symlink_to_directory ((struct fileinfo const *) b);  \
       if (a_is_dir && !b_is_dir)                   \
         return -1;         /* a goes before b */           \
       if (!a_is_dir && b_is_dir)                   \