Substring substitution in bash

my problem of today is to replace in a string like this --> 6427//6422 6429//6423 6428//6421

every // with a ,. I tried with different commands:

• finalString=${startingString//[//]/,} doesn't work

• fileTemp=$(echo -e "$line\n" | tr "//" "," does a double substitution like this:

  hello//world ---> hello,,world

Someone has an idea of a way to do it?

You can use BASH string manipulations (need to escape / with \/):

s='6427//6422 6429//6423 6428//6421'
echo "${s//\/\//,}"
6427,6422 6429,6423 6428,6421

Similarly using awk:

awk -F '//' -v OFS=, '{$1=$1}1' <<< "$s"
6427,6422 6429,6423 6428,6421

PS: tr cannot be used here since tr translates each character in input to another character in the output and here you're dealing with 2 characters //.