Replace one substring for another string in shell script

Question

I have \"I love Suzi and Marry\" and I want to change \"Suzi\" to \"Sara\".

#!/bin/bash
firstString=\"I love Suzi and Marry\"
secondString=\"Sara\"
# do some         


        

Answer 1

To replace the first occurrence of a pattern with a given string, use ${parameter/pattern/string}:

#!/bin/bash
firstString="I love Suzi and Marry"
secondString="Sara"
echo "${firstString/Suzi/$secondString}"    
# prints 'I love Sara and Marry'

To replace all occurrences, use ${parameter//pattern/string}:

message='The secret code is 12345'
echo "${message//[0-9]/X}"           
# prints 'The secret code is XXXXX'

(This is documented in the Bash Reference Manual, §3.5.3 "Shell Parameter Expansion".)

Note that this feature is not specified by POSIX — it's a Bash extension — so not all Unix shells implement it. For the relevant POSIX documentation, see The Open Group Technical Standard Base Specifications, Issue 7, the Shell & Utilities volume, §2.6.2 "Parameter Expansion".