Really simple to explain :
How to rename
/folder1/something.test.html
/folder1/somethingElse.test.html
/folder2/againsomething.test.html
/canBeHereAl
You can do this:
name1="/folder1/something.test.html"
name2="${name1/%.html/2.html}"
echo "$name2"
#mv "$name1" "$name2"
Output:
/folder1/something.test2.html
.html
is being replaced with 2.html
at the end of the string.
To go back i.e test2 -> test
:
name2="/folder1/something.test2.html"
name1="${name2/%2.html/.html}"
See the Bash Manual for more info on Parameter Expansion.