UNIX for Dummies Questions & Answers

${f} is the same that $f, the variable, right?
There are two parts in shell expansion ${f%.*}, the `%' and the glob pattern `.*' (this is not a regular expression), in this case a dot followed by anything.
The `%' says remove starting from the end of the string as minimum as possible of that which matches the pattern.
If there were two `%%' it would be as much as it is able to match the pattern, starting at the utmost right of the string.

An example:

Code:

[aia@ludus krsnadasa]$ f="krsnadasa.original"
[aia@ludus krsnadasa]$ echo "$f"
krsnadasa.original
[aia@ludus krsnadasa]$ echo "${f%.*}"
krsnadasa
[aia@ludus krsnadasa]$ echo "${f%.*}.bak"
krsnadasa.bak

mv -v "$f" "${f%.*}.bak" expands to mv --verbose krsnadasa.original krsnadasa.bak

Thanks RudiC and Aia

I just went through documentation of Bash Paramter expansion. Post that these things became quite clear to me. Thank you for your time..