well, I can try explaining..
ls *.pdf - its clear i guess.
now..
Quote:
sed 's/\(.*\)1\(\..*\)/mv & \1\2/'
this matches anything1.anything i.e the filename like 01_anote1.pdf
and replacing this by mv anything1.anything anything.anything
here - "anything" before dot means filename and "anything" after dot means extntion.
so the output is mv 01_anote1.pdf 01_anote.pdf which is redirecting to the shell to execute the mv command.
now in sed... & is used to replace what is matched previously.
\1 \2 are used to recall the saved regex by escaped paranthesis.
as far as i know m you can have max 9 save regex/strings.
@Franklin52 or other : if there is something else in your command please share.