<name>My name is Tom but people call me as XYZ but my actual name is Tommy!</name>
Example:
(?<=<name>)[a-zA-Z]*(Tom)[a-zA-Z]*(?=<\/name>),
Since the name tag cannot have any other tags inside, the regex that can solve the issue is
(?:\G(?!^)|<name>)[^<]*?\K\bTom\b
See the regex demo. Replace with Harry.
Details
(?:\G(?!^)|<name>) - the end of the previous successful match (\G(?!^)) or (|) the <name> substring[^<]*? - any 0+ chars other than <, as few as possible\K - match reset operator\bTom\b - whole word Tom (remove \b word boundaries if you need to match Tom in Tommy).NOTE: If you also want to match Tommy, replace \bTom\b with \bTom(?:my)?\b.
Find what : (?<=<name>)(.*?)(Tom)(?=\b.*</name>)
Replace with : $1Harry
Detail :
Balise name : (?<=<name>)
Anything between name and Tom(.*?)
Tom (Tom)
A boudary to check the end of the word Tom(?=\b
Anything between tom and the closing name balise .*
The closing balise </name>)
Reinject what's between the balise name and tom$1
Replacing Tom by HarryHarry
<name>tag contain other tags?