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Bash scripting question (sh.itjust.works)
submitted 11 months ago by to c/linux@lemmy.ml
17 comments fedilink hide all child comments
 

Hello everyone,

Hoping that this is a good place to post a question about Bash scripting. My wife and I have run into a problem in PhotoPrism where it keeps tagging pictures and videos with similar names together and so the thumbnail and the video do not match. I decided that rather than try to get her iPhone to tweak its naming it's easier to just offload to a directory then rename every file to a UUID before sending to photoprism. I'm trying to write a bash script to simplify this but cannot get the internal loop to fire. The issue appears to be with the 'while IFS= read -r -d '' file; do' portion. Is anyone able to spot what the issue may be?

#! /bin/bash
echo "This script will rename all files in this directory with unique names. Continue? (Y/N)"
read proceed
if [[ "$proceed" == "Y" ]]; then
	echo "Proceed"
	#use uuidgen -r to generate a random UUID.
	#Currently appears to be skipping the loop entirely. the find command works so issue should be after the pipe.
	   
# Troubleshooting
#Seems like changing IFS to $IFS helped. Now however it's also pulling others., don't think this is correct.
#verified that the find statement is correct, its the parsing afterwards that's wrong.
#tried removing the $'\0' after -d as that is string null in c. went to bash friendly '' based on https://stackoverflow.com/questions/57497365/what-does-the-bash-read-d-do
#issue definitely appears to be with the while statement
	find ./ -type f \( -iname \*.jpg -o -iname \*.png \) | while IFS= read -r -d '' file; do
	   echo "in loop"
	   echo "$file"
	   #useful post https://itsfoss.gitlab.io/post/how-to-find-and-rename-files-in-linux/
	   #extract the directory and filename
	   dir=$(dirname "$file")
	   base=$(basename "$file")
	   echo "'$dir'/'$base'"
	   #use UUID's to get around photoprism poor handling of matching file names and apples high collision rate
	   new_name="$dir/$(uuidgen -r)"
	   echo "Renaming ${file} to ${new_name}"
	   #mv "$file" "$new_name" #uncomment to actually perform the rename.
	done
	echo "After loop"
else
	echo "Cancelling"
fi
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[–] 3 points 11 months ago*

I'm totally in favor of people asking other people for help with these things. But here's what Claude gave.

Found the Issue!

The problem is a mismatch between your find output and what read expects:

  • find with a regular pipe outputs newline-separated filenames
  • read -r -d '' expects null-terminated input (the -d '' means "use null byte as delimiter")

Solution 1: Use -print0 with find (Recommended)

Change your find command to use -print0:

find ./ -type f \( -iname "*.jpg" -o -iname "*.png" \) -print0 | while IFS= read -r -d '' file; do

Solution 2: Remove -d '' from read

find ./ -type f \( -iname "*.jpg" -o -iname "*.png" \) | while IFS= read -r file; do

Additional Issues to Fix:

  1. Quote your wildcards: -iname \*.jpg should be -iname "*.jpg" to prevent shell expansion
  2. File extension preservation: Your script generates UUIDs but loses the file extension (.jpg, .png). You probably want to keep those!

Improved Script:

#! /bin/bash
echo "This script will rename all files in this directory with unique names. Continue? (Y/N)"
read proceed
if [[ "$proceed" == "Y" ]]; then
    echo "Proceed"
    
    find ./ -type f \( -iname "*.jpg" -o -iname "*.png" \) -print0 | while IFS= read -r -d '' file; do
        echo "in loop"
        echo "$file"
        
        # Extract the directory and extension
        dir=$(dirname "$file")
        ext="${file##*.}"  # Get file extension
        
        # Generate new name with UUID but keep extension
        new_name="$dir/$(uuidgen -r).$ext"
        
        echo "Renaming ${file} to ${new_name}"
        # mv "$file" "$new_name"  # Uncomment to actually perform the rename
    done
    echo "After loop"
else
    echo "Cancelling"
fi

The key changes:

  • Added -print0 to find
  • Quoted the wildcard patterns
  • Preserved file extensions using ${file##*.}

Try this and let me know if it works!

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