Search and replace using key-value pairs

sedDictFnR.sh

#!/bin/bash

# We're gonna assume your "key-value" pairs is in a normal bash array.
fakedict=(
  key1 value1
  key2 value2
  key3 value3
)

# Constructs a string like "s/key1/value1/g; s/key2/value2/g; s/key3/value3/g"
sedPattern="$(printf 's/%s/%s/g; ' "${fakedict[@]}")" 

# Use the pattern string however you need
sed -i "$sedString" /path/to/file.txt