Shell Programming and Scripting

Here is what I have so far

Code:

#!/bin/bash

while [ $# -gt 0 ]
do
        read image
        jpegtopnm $image | pnmscale -height 200 | pnmtojpeg > $image-thumb
        echo $image-thumb
        shift
done

I sorta threw some pseudocode in there to demonstrate what I'm trying to do. . Where I am stuck is, I am trying to read in a list of images. The while/do works fine but I get confused as to how to represent all the images in the list as a single item such as '$image' because I need to scale all of them and them spit them back out on the command line with new names by adding -thumb to their names. Also I'm trying to make it JPG specific meaning if the list gets a .html file for example by accident it should skip over it. My biggest problem is I dont know how to represent a list of items as a single variable if that is the right word. Any help just to get started in the right direction is appreciated. . thank you

---------- Post updated at 04:31 PM ---------- Previous update was at 04:29 PM ----------

edit here is an update to what I have changed

Code:

#!/bin/bash

for img in *.jpg
do

        jpegtopnm $img | pnmscale -height 200 | pnmtojpeg > $img-thumb
        echo $img
        shift
done

You can remove the 'shift', it does nothing there.

Does this code do what you want, or do you still have questions?

Hi thanks for the reply

this is what I am getting back right now im not entirely sure but it seems to be an improvement

You mean image-thumb.jpg rather than image.jpg-thumb? You first have to strip the extension off, then back on again.

Code:

jpegtopnm "$img" | pnmscale -height 200 | pnmtojpeg > "${img%.jpg}-thumb.jpg"

then if the script is ran again, you'll make thumbnails of your thumbnails, so you can skip those *-thumb.jpg files:

Code:

for img in *.jpg; do
    [[ "$img" = *-thumb.jpg ]] && continue