Question

I need to write a shell script to convert the image format from .png to .tif. The script is as follows:

#!/bin/sh

for f in `ls *.png`
do
    convert $f $f.tif
done

But doing this will append the .tif format to the existing filename. ie if the image is abc.png the $f will have abc.png and after converting the filename becomes abc.png.tif. This is not what I want. I need it to be abc.tif. How do I manipulate $f to remove .png?

Answer 1

This should work for you:

#!/bin/bash

for file in *.png
do
    filename=$(basename "$file")
    filename=${filename%.*}
    convert $file $filename.tif
done

A line-by-line walkthrough of how this works:

• for file in *.png – you don’t need command substitution ls *.png to get the list of files with png extension. The wildcard * will auto-expand in shell to match the list of files in cwd; and in this case the list of files ending in .png.
• filename=$(basename "$file") – this is only for defensive programming; it gets the actual name of the file
• filename=${filename%.*} – this removes the extension from filename
• convert $file $filename.tif – runs your actual convert command