Bash shell script to grab a substring?

Question

For example- $x=xyz.2.3.4.fc15.i686 output require=15 (i.e. between fc and .i686)

Answer 1

$ x=xyz.2.3.4.fc15.i686
$ y=${x#*fc}
$ z=${y%.*}
$ echo $z
15

• # left strip
• % right strip