Get bash script source directory (follow symlinks etc)

bash_script_source.sh

#!/bin/bash
# Taken from answer: https://stackoverflow.com/questions/59895/how-to-get-the-source-directory-of-a-bash-script-from-within-the-script-itself/246128#246128

# Option 1: One Liner
#
# "It will work as long as the last component of the path used to find the script is not a symlink (directory links are OK)"
DIR="$( cd "$( dirname "${BASH_SOURCE[0]}" )" >/dev/null 2>&1 && pwd )"

# Option 2: Bulletproof
# 
# "If you also want to resolve any links to the script itself"
SOURCE="${BASH_SOURCE[0]}"
while [ -h "$SOURCE" ]; do # resolve $SOURCE until the file is no longer a symlink
    DIR="$( cd -P "$( dirname "$SOURCE" )" >/dev/null 2>&1 && pwd )"
    SOURCE="$(readlink "$SOURCE")"
    [[ $SOURCE != /* ]] && SOURCE="$DIR/$SOURCE" # if $SOURCE was a relative symlink, we need to resolve it relative to the path where the symlink file was located
done
DIR="$( cd -P "$( dirname "$SOURCE" )" >/dev/null 2>&1 && pwd )"

# Option 2 Verbose output
#
# Use the following to gain an understanding on how option 2 works
SOURCE="${BASH_SOURCE[0]}"
while [ -h "$SOURCE" ]; do # resolve $SOURCE until the file is no longer a symlink
    TARGET="$(readlink "$SOURCE")"
    if [[ $TARGET == /* ]]; then
        echo "SOURCE '$SOURCE' is an absolute symlink to '$TARGET'"
        SOURCE="$TARGET"
    else
        DIR="$( dirname "$SOURCE" )"
        echo "SOURCE '$SOURCE' is a relative symlink to '$TARGET' (relative to '$DIR')"
        SOURCE="$DIR/$TARGET" # if $SOURCE was a relative symlink, we need to resolve it relative to the path where the symlink file was located
    fi
done
echo "SOURCE is '$SOURCE'"
RDIR="$( dirname "$SOURCE" )"
DIR="$( cd -P "$( dirname "$SOURCE" )" >/dev/null 2>&1 && pwd )"
if [ "$DIR" != "$RDIR" ]; then
    echo "DIR '$RDIR' resolves to '$DIR'"
fi
echo "DIR is '$DIR'"