Create a Deep Shadow Link Tree

lndirs.sh

#! /bin/sh

# lndir - create deep shadow link tree
#
# Time stamp <1989/11/28 18:56:54 gildea>
# By Stephen Gildea <gildea@bbn.com> based on
#  XConsortium: lndir.sh,v 1.1 1988/10/20 17:37:16 jim Exp
#
# Modified slightly for ImageMagick by Bob Friesenhahn, 1999
#   * https://github.com/ImageMagick/ImageMagick/blob/main/config/lndir.sh
#   * https://github.com/ImageMagick/WizardsToolkit/blob/main/config/lndir.sh
#
# Updated and modified by Matthew Sheets, 2026-01-10
#
# Used to create a copy of the a directory tree that has links for all
# non-directories.  If you are building the distribution on more than
# one machine, you should use this script.
#
# A key difference between this script and the "lndir" executable from the
# X.org project is that when this script encounters a linked directory, it
# will create a new directory in the shadow link tree and then continue
# linking files recursively.  X.org's lndir executable, on the other hand,
# will merely create a link to the linked directory and stop further recursively
# processing on that particular path.
#
# USAGE EXAMPLE:
# If your main sources are located in /usr/local/src/X and you would like
# your link tree to be in /usr/local/src/new-X, do the following:
#
#   %  mkdir /usr/local/src/new-X
#   %  cd /usr/local/src/new-X
#   %  lndir ../X
#
# Improvements over R3 version:
#   Allows the fromdir to be relative: usually you want to say "../dist"
#   The name is relative to the todir, not the current directory.
#
# Bugs in R3 version fixed:
#   Do "pwd" command *after* "cd $DIRTO".
#   Don't try to link directories, avoiding error message "<dir> exists".
#   Barf with Usage message if either DIRFROM *or* DIRTO is not a directory.
#
# Changes over ImageMagick version:
#   ShellCheck'd.
#   More robust capturing of script name for when called recursively.
#   Now also links hidden files (those beginning with ".").
#   Resolves encountered file links to create a link directly to the target
#     (like X.org's lndir).

SCRIPTNAME="$(basename "$0")"
SCRIPTPATH="$(realpath "$0")"
USAGE="Usage: $SCRIPTNAME fromdir [todir]"

if [ $# -lt 1 ] || [ $# -gt 2 ]
then
    echo "$USAGE"
    exit 1
fi

DIRFROM="$1"

if [ $# -eq 2 ];
then
    DIRTO="$2"
else
    DIRTO=.
fi

if [ ! -d "$DIRTO" ]
then
    echo "$SCRIPTNAME: \"$DIRTO\" is not a directory"
    echo "$USAGE"
    exit 2
fi

cd "$DIRTO" || exit 1

if [ ! -d "$DIRFROM" ]
then
    echo "$SCRIPTNAME: \"$DIRFROM\" is not a directory"
    echo "$USAGE"
    exit 2
fi

pwd="$(pwd)"

if [ "$(cd "$DIRFROM" ; pwd)" = "$pwd" ]
then
    echo "$pwd: FROM and TO are identical!"
    exit 1
fi

for file in .* *
do
    if [ ! -d "$DIRFROM/$file" ]
    then
        test -r "$file" || ln -s "$(realpath --relative-to=. "$DIRFROM/$file")" .
    else
        #echo "$file":
        test -d "$file" || mkdir "$file" && chmod 777 "$file"
        (
            cd "$file" || exit 1
            pwd="$(pwd)"
            case "$DIRFROM" in
                /*) ;;
                *)  DIRFROM="../$DIRFROM" ;;
            esac
            if [ "$(cd "$DIRFROM/$file" ; pwd)" = "$pwd" ]
            then
                echo "$pwd: FROM and TO are identical!"
                exit 1
            fi
            "$SCRIPTPATH" "$DIRFROM/$file"
        )
    fi
done