I'm not sure I understand how the "maximum 8" clause is supposed to apply, but the naive approach would be something like this:
sed 's/\((TAB)\)\{2,8\}/(TAB)/g'
If you have a fixed extension, POSIX basename supports exactly the cropping you're attempting:
basename "$var" .ext
If you don't, zsh expansion supports exactly what you're trying:
If a ${...} type parameter expression or a $(...) type command substitution is used in place of name above, it is expanded first and the result is used as if it were the value of name. Thus it is possible to perform nested operations: ${${foo#head}%tail} substitutes the value of $foo with both ‘head’ and ‘tail’ deleted.
So in zsh
echo ${${var##*/}%.*}
will do what you expected.
If you're committed to Bash, and you want to save lines, you could use sed:
sed -e 's/\.[^.]*$//' <<<"${var##*/}"
That's just a regular-expression replacement of everything after the last . with nothing, after losing the prefix the same way you are now. I don't see this particularly saving memory over the two-line version, however, and it's probably less comprehensible too.
Note that there's no reason you can't use the same variable right through the process:
var2=${var##*/}
var2=${var2%.*}
The expansion happens before the assignment, so this is safe. If your concern is a really long filename being stored twice, that won't happen now, but I don't think that is a realistic problem.
Best Answer
The
{is before$. It should be${version}:)