Iterative replacement of substrings in bash - bash

Question

I'm trying to write a simple script to make several replacements in a big text file. I've a "map" file which contains the records to be searched and replaced,one per line,separated by a space, and a "input" file where I need the changes to be done. The examples files and the script I wrote are beneath.
Map file
new_0 old_0
new_1 old_1
new_2 old_2
new_3 old_3
new_4 old_4
Input file
itsa(old_0)single(old_2)string(old_1)with(old_5)ocurrences(old_4)ofthe(old_3)records
Script
#!/bin/bash
while read -r mapline ; do
mapf1=`awk 'BEGIN {FS=" "} {print $1}' <<< "$mapline"`
mapf2=`awk 'BEGIN {FS=" "} {print $2}' <<< "$mapline"`
for line in $(cat "input") ; do
if [[ "${line}" == *"${mapf2}"* ]] ; then
sed "s/${mapf2}/${mapf1}/g" <<< "${line}"
fi
done < "input"
done < "map"
The thing is that the searches and replaces are made correctly, but I can't find a way to save the output of each iteration and work over it in the next. So, my output looks like this:
itsa(new_0)single(old_2)string(old_1)withocurrences(old_4)ofthe(old_3)records
itsa(old_0)single(old_2)string(new_1)withocurrences(old_4)ofthe(old_3)records
itsa(old_0)single(new_2)string(old_1)withocurrences(old_4)ofthe(old_3)records
itsa(old_0)single(old_2)string(old_1)withocurrences(old_4)ofthe(new_3)records
itsa(old_0)single(old_2)string(old_1)withocurrences(new_4)ofthe(old_3)records
Yet, the desired output would look like this:
itsa(new_0)single(new_2)string(new_1)withocurrences(new_4)ofthe(new_3)records
May anyone bring some light in this darkly waters??? Thanks in advance!

Answer 1

Improving the existing script
Improvements:
Use "$()" instead of ``. It supports whitespace and is easier to read.
Don't execute sed for each line. sed already loops over all lines and is faster than a loop in bash.
The adapted script:
text="$(< input)"
while read -r mapline; do
mapf1="$(awk 'BEGIN {FS=" "} {print $1}' <<< "$mapline")"
mapf2="$(awk 'BEGIN {FS=" "} {print $2}' <<< "$mapline")"
text="$(sed "s/${mapf2}/${mapf1}/g" <<< "$text")"
done < "map"
echo "$text"
The variable $text contains the complete input file and is modified in each iteration. The output of this script is the file after all replacements were done.
Alternative approach
Convert the map file into a pattern for sed and execute sed just once using that pattern.
pattern="$(sed 's#\(.*\) \(.*\)#s/\2/\1/g#' map)"
sed "$pattern" input
The first command is the conversion step. The file
new_0 old_0
new_1 old_1
...
will result in the pattern
s/old_0/new_0/g
s/old_1/new_1/g
...

Answer 2

It is possible in GNU Awk as follows,
awk 'FNR==NR{hash[$2]=$1; next} \
{for (i=1; i<=NF; i++)\
{for(key in hash) \
{if (match ($i,key)) {$i=sprintf("(%s)",hash[key];break;)}}}print}' \
map-file FS='[()]' OFS= input-file
produces an output as,
itsa(new_0)single(new_2)string(new_1)withold_5ocurrences(new_4)ofthe(new_3)records

Answer 3

Another in Gnu awk, using split and ternary operator(s):
$ awk '
NR==FNR { a[$2]=$1; next }
{
n=split($0,b,"[()]")
for(i=1;i<=n;i++)
printf "%s%s",(i%2 ? b[i] : (b[i] in a? "(" a[b[i]] ")":"")),(i==n?ORS:"")
}' map foo
itsa(new_0)single(new_2)string(new_1)withocurrences(new_4)ofthe(new_3)records
First you read in the map to a hash. When processing the file, split all records by ( and ). Every other could be in the map (i%2==0). While printfing test with ternary operator if matches are found from a and when there is a match, output it parenthesized.