Add a tool to take the pain out of ln -s

bin/lns

@@ -0,0 +1,74 @@
+#!/usr/bin/python
+# (c) 2015 Taeyeon Mori
+# A simple script to make ln -s less painful
+#
+# Because of how symbolic links work (they're just a pathname that the OS reads and follows),
+# the link target path must always be relative to the symlink's containing directory, OR
+# an absolute path altogether. Unfortunately, ln -s does not automatically solve this issue
+# which makes it painful to create a relative symlink somewhere outside the current working
+# directory (It screws up shell completion for instance)
+# This script performs the path transformation before creating the link and can therefore be
+# used without worries of creating broken symlinks because one forgot to apply the correct
+# relative adjustment to the target path
+#
+# ex:
+# $ lns -v some-file dir/some-link
+# ln -s '../some-file' 'dir/some-link'
+# $ lns -v file ../derp/link # inside a directory called 'herp'
+# ln -s '../herp/file' '../derp/link'
+
+
+import os
+import argparse
+
+
+def transport_relpath(path, old_anchor, new_anchor):
+    """
+    :brief: Transport a relative path from one anchor to another
+    Anchors must both be absolute paths, path must be relative (to old_anchor)
+    """
+    return os.path.relpath(os.path.normpath(os.path.join(old_anchor, path)), new_anchor)
+
+
+def verbose_symlink(target, dest):
+    print("ln -s '%s' '%s'" % (target, dest))
+    return os.symlink(target, dest)
+
+
+def main(argv):
+    # Command line interface to make_symlink()
+    parser = argparse.ArgumentParser(prog=argv[0],
+                                     description="A 'ln -s' command that automatically translates relative target paths to be relative to the resulting symlink's containing directory when necessary.")
+    parser.add_argument("target", help="The file(s) to create symlink(s) to", nargs="+")
+    parser.add_argument("destination", help="The path of the symbolic link(s) to create")
+    parser.add_argument("-v", "--verbose", help="Print every operation",
+                        dest="symlink", const=verbose_symlink, action="store_const", default=os.symlink)
+
+    args = parser.parse_args(argv[1:])
+
+    # Multiple
+    if len(args.target) > 1:
+        if not os.path.isdir(args.destination):
+            print("Destination must be an existing directory when multiple targets are passed!")
+        for target in args.target:
+            dest = os.path.join(args.destination, os.path.basename(target))
+            args.symlink(target if os.path.isabs(target) else transport_relpath(target, os.curdir, args.destination), dest)
+
+    # One
+    else:
+        target = args.target[0]
+
+        dest = ldir = args.destination
+        if os.path.isdir(dest):
+            dest = os.path.join(dest, os.path.basename(target))
+        else:
+            ldir = os.path.dirname(dest)
+
+        args.symlink(target if os.path.isabs(target) else transport_relpath(target, os.curdir, ldir), dest)
+
+    return 0
+
+
+if __name__ == "__main__":
+    import sys
+    sys.exit(main(sys.argv))