make-goroot-symlink.sh

#!/bin/bash
# Copyright 2018 The Fuchsia Authors. All rights reserved.
# Use of this source code is governed by a BSD-style license that can be
# found in the LICENSE file.
#
# Make a symlink, handling the case where the source is a directory
# by removing the source first.
# "ln -sf" doesn't work in this case: the symbolic link is placed in the
# directory named LINK-NAME.
# For paranoia purposes, this script only works if the basename of
# TARGET and LINK-NAME are "goroot". This is to avoid accidents resulting
# in rm -rf removing way more than intended.

set -e

if [[ $# != 2 ]]
then
  echo >&2 "Usage: $(basename $0) TARGET LINK-NAME"
  exit 1
fi

declare -r TARGET=$1
declare -r LINK_NAME=$2

if [[ $(basename "$TARGET") != "goroot" ]]
then
  echo >&2 "TARGET basename is not goroot"
  exit 1
fi
if [[ $(basename "$LINK_NAME") != "goroot" ]]
then
  echo >&2 "LINK-NAME basename is not goroot"
  exit 1
fi

/bin/rm -rf "$LINK_NAME"
/bin/ln -s "$TARGET" "$LINK_NAME"