Pure bash scripts for removing duplicates from PATH

uniq-path-bash3.sh

#!/bin/bash

# A pure-bash (3.x+) function for removing duplicates from PATH
# Use:
#  $ export PATH=`uniq-path-bash3.sh`

# Separate on ':'
OLD_IFS=$IFS
IFS=":"
# Collect unique items in NEW_PATH
NEW_PATH=""
for I in $PATH
do
  REGEX="(^|:)$I(:|$)"
  # Is the path already present?
  if [[ ! $NEW_PATH =~ $REGEX ]]; then
    # Is this the first item?
    if [ -z "$NEW_PATH" ]; then
      NEW_PATH="$I"
    else
      NEW_PATH="$NEW_PATH:$I"
    fi
  fi
done
# Re-instate old file separator
IFS="$OLD_IFS"
echo "$NEW_PATH"

uniq-path-bash4.sh

#!/bin/bash

# A pure-bash (4.x+) function for removing duplicates from PATH
# Use:
#  $ export PATH=`uniq-path-bash4.sh`

KEEP=()
declare -A SEEN
OLD_IFS=$IFS
IFS=":"
for I in $PATH
do
  if [[ ${SEEN[$I]} != 1 ]]; then
    KEEP+=($I)
    SEEN[$I]=1
  fi
done
echo "${KEEP[*]}"
IFS=$OLD_IFS