ksh rename multiple files with prefix entered by user to another prefix entered by user - rename

Question

pretty new to scripting...
Lets say I have multiple files with multiple prefixes in current directory. I need to rename them based on user input.
Let's say I have aaa_file.dat and bbb_file.dat aaa_log.dat ccc.txt and so on.
Script will ask to enter "old prefix" and enter "new prefix" and search files with "old" prefix and mv it into name with "new" prefix.
print "enter old prefix" ;
read old ;
print "enter new prefix" ;
read new ;
find and rename part is where I get stuck..
for $old in * ;
do mv $old_* $new_* ;
done
If I enter as user aaa and the zzz my files, my result should be:
aaa_file.dat and aaa_log.dat are now named zzz_file.dat zzz_log.dat

Answer 1

You have some mistakes in
for $old in * ;
do
mv $old_* $new_* ;
done
When you use a for-loop, a value will be assigned to the loop variable. So drop the $ in for $old in *.
You already have assigned a value to the variable old, you do not want to overwrite it with a new value. Use a new variable like for file in * (or for file in ${old}*).
Variables can have understores in their name. $old_* is not the same as ${old}_*. Get used to using those braces in all cases except for one character variables when they are followed by a space or quote.
You are hoping for some magic, when you write ${new}_*. The variable will be extended to its value (like zzz), the shell searches for files starting with zzz_ (non found) and will try (when you hae written mv ${old}_* ${new}_*) to move all files with their name starting with aaa_ to a directory called zzz_*.
So construct a new filename from the old one with something like sed:
The new filename must be constructed from the old filename.
for file in ${old}_*; do
newfile=$(echo "${file}"| sed "s/^${old}_/${new}_/")
# Remove the word echo when the command shows the mv commands you like
echo mv "${file}" "${newfile}"
done