How to use sed to change file extensions?

Question

I have to do a sed line (also using pipes in Linux) to change a file extension, so I can do some kind of mv *.1stextension *.2ndextension like mv *.txt *.

Answer 1

This may work:

find . -name "*.txt" | 
sed -e 's|./||g' | 
awk '{print "mv",$1, $1"c"}' | 
sed -e "s|\.txtc|\.c|g" > table;
chmod u+x table;
./table

I don't know why you can't use a loop. It makes life much easier :

newex="c";  # Give your new extension
for file in *.*;  # You can replace with *.txt instead of *.*
do 
 ex="${file##*.}";    # This retrieves the file extension
 ne=$(echo "$file" | sed -e "s|$ex|$newex|g"); # Replaces current with the new one
 echo "$ex";echo "$ne";
 mv "$file" "$ne";
done