Replacing values in files is incredibly easy with sed. Here’s some examples:
sed 's/match/replace/g' file.txt
Find match, replace with replace, globally (all matches), in file.txt
sed 's/match/replace/g' file.txt > file2.txt
Same as before, but write results to new file, file2.txt
sed -n 's/match/replace/p' file.txt
-n suppresses output of the results, but /p prints out just the matching patterns that are replaced.
sed -i.old 's/match/replace/g' file.txt
Replace matches in the input file with inline replace (-i), renaming original file file.txt.old and writing inline replace results to file.txt