Renaming files with a year prefix from the beginning of the filename to the end

Extreme novice here attempting to figure out how to rename a bunch of files in a directory. I have hundreds of media files that all follow the same syntax for the file name:

year - title of movie.avi

I would like to write a script that removes the year and the " - " from the beginning of the file name and appends it onto the end. End result:

title of movie - year.avi 

(or something similar. I don't really need the dash)

The problem I am running into with a for loop like the one below is that, since the file names have spaces in them, my script keeps parsing each word instead of each full filename.

for file in $(ls)

I haven't gotten very far as a result.

You can use rename command with regexp:

rename 's/(\d+) - (.*)\.avi/$2 - $1.avi/' *.avi

explained:

• rename - command (you may have to install it)
• s/<match>/<replacement>/ (substitute command)
• .*avi run above on all .avi files

Match regex:

• (\d+) matches and captures group ($1) of one or more digits
• - matches literal -
• (.*) match anything and capture in group ($2)
• \.avi match .avi (dot is escaped)

Replacement:

• $2 - $1.avi - paste second group (title), then dash, then first group (year), then file extension

learn regex, <3 Regex. Steer away from using bash for looping over files, as splitting strings to tokens is hard to understand and often confusing, and you may just overlook some things if you don't understand them.

You could also use mmv for this. First install it using:

sudo apt install mmv

Then from the directory with your files run:

mmv -n '???? - *.avi' '#5 - #1#2#3#4.avi'

The first expression ('???? - *.avi') matches any file that starts with 4 characters (a ? for each one of the 4 digits of the year), is then followed by a hyphen surrounded by spaces (-) and any number of any character (* for the title) and ends with .avi.

The second expression ('#5 - #1#2#3#4.avi') takes each match (which is of the form #n) and arranges it in the way shown to achieve your desired result, i.e the tile first and the year after, separated by -.

The above command will show previews of the changes that will be made. If you are satisfied with them, run the command without the -n flag.

In bash only:

for f in *.avi; do 
    t="${f#*- }"; t="${t%.*}"; echo mv -n -- "$f" "${t} - ${f%% *}.${f##*.}";
  done

One thing you can do in Bash or Korn Shell is change the Internal Field Separator. By default, the $IFS includes spaces, tabs, and carriage returns or newlines. You can change the IFS to ONLY use the newline at the end of the line.

Example:

ORIGINAL_IFS="${IFS}"
IFS=$(echo "\n")
for LOOP in $(ls)
do
  print ${LOOP}
done
IFS="${ORIGINAL_IFS}"

Instead of just using print at that stage in the loop, you can use awk or cut and grab the year off the beginning of the line.

You may want to reset the IFS back to its original value before moving on to the next part of the script, in case it affects other logic.