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I found this script to convert images to webp format.

#!/bin/bash -x

# converting JPEG images
find $1 -type f -and \( -iname "*.jpg" -o -iname "*.jpeg" \) \
-exec bash -c '
webp_path=$(sed 's/\.[^.]*$/.webp/' <<< "$0");
cwebp -quiet -q 90 "$0" -o "$webp_path";
rm -rf $webp_path;' {} \;

The folder which is provided as input is as below.

root@ip-10-0-1-46:/var/images/newlocallego/12345# tree
.
└── 01234
    ├── 001.jpg
    ├── 002.jpg
    ├── index.htm
    └── main.jpg

1 directory, 4 files

i am executing as ./webpconvert.sh /var/images/newlocallego/12345

However, its neither creating the webp files nor removing the jpg files and not giving any error. What am i missing.

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  • 1
    I don't know what cwebp does, but if it's writing to $webp_path, then you are immediately removing that afterwards. You could also get rid of sed with webp_path=${0%.*}.webp. Commented Jan 12, 2022 at 11:11
  • damn. yes, you are right.. i am removing the converted images. i should be removing the original files which are referenced by $0. It works now.. Thank you. Commented Jan 12, 2022 at 11:16
  • Quoting in the script is not right. In unfortunate circumstances this rm -rf may remove a lot. Even if the original author wanted to remove the file just created, I wonder why they used -r. Commented Jan 12, 2022 at 11:17
  • a contributing factor: the ' after sed closes the ' after -exec bash -c! Commented Jan 12, 2022 at 11:21

1 Answer 1

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You are immediately removing your output file after creating it. You also have issues with quoting in the bash -c script's command substitution around sed, and there are a few instances of variables not being quoted at all.

Corrected variant:

find "$@" -type f \( -iname '*.jpg' -o -iname '*.jpeg' \) -exec bash -c '
    for pathname do
        cwebp -quiet -q 90 -o "${pathname%.*}.webp" -- "$pathname" &&
        rm -f -- "$pathname"
    done' bash {} +

This makes the operation more efficient by calling bash -c with batches of found files instead of once per file.

The original file is not removed unless cwebp exited successfully. The .webp filename suffix replaces the original filename suffix by means of a standard parameter substitution, rather than by using sed. Note that -r is not needed with rm when removing files.

The script now also support taking multiple directories on the command line.

Without using find, in bash:

shopt -s nullglob dotglob nocaseglob
shopt -s globstar

for dirpath do
    for pathname in "$dirpath"/**/*.{jpg,jpeg}; do
        [ ! -f "$pathname" ] && continue
    
        cwebp -quiet -q 90 -o "${pathname%.*}.webp" -- "$pathname" &&
        rm -f -- "$pathname"
    done
done

The only difference is that this bash loop would also process symbolic links to regular files matching the patterns. If that is an issue, then change the -f test in the inner loop to

if [ ! -f "$pathname" ] || [ -h "$pathname" ]; then
    continue
done
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