Bash Scripting Help, can't get values to compare

seanferd · 12-20-2013, 02:48 PM

Hi everyone,

I'm having some trouble with a Bash script that I wrote quite a while ago. I'm running on Debian Wheezy at the moment, the last time I knew this worked was on Lenny probably.

Here's the snippet that I'm having trouble with:

Code:

for i in *.jpg;
do
        DIM=`identify $i | cut -d' ' -f3 | cut -dx -f1,2`;
        WIDTH=`echo $DIM | cut -dx -f1`;
        HEIGHT=`echo $DIM | cut -dx -f2`;

        if [ $HEIGHT -gt $WIDTH ]; then
                mv $i ./tall;
        fi
done

Essentially the 'if' is never validating these two and I have no idea why. It previously worked fine, but after upgrading it just doesn't seem to like it. I searched around and found that bash isn't typed so this should be fine as well.

What I'm cutting out for the parameters is the filesize. Echoing them reveals that it's correctly picking it up e.g. 1900x1200 - though, again, the comparison is always false. If anyone can provide some insight here, I'd be extremely grateful.

If anyone cares, the script itself was written to resize a bunch of images. It runs through and looks at whether it's landscape or portrait and then moves the image to a new directory if so. Eventually it will come back and resize based on what directory the files are in. I'd love to just rewrite it, but the script is huge and this portion is the only piece that doesn't seem to work correctly anymore.

Thanks for any thoughts!

unSpawn · 12-20-2013, 05:46 PM

Quote:

Originally Posted by seanferd

Essentially the 'if' is never validating these two and I have no idea why.

This snippet is self-contained and small enough for you to be able to run it on say three files and show us the actual output

Code:

set -vx
find /some/path -type f -iname \*.jpg | while read ITEM; do
 DIM=($(identify "${ITEM}")); [ "${DIM[2]}" != "${DIM[2]//x/}" ] || break
 [ ${DIM[2]//x*} -gt ${DIM[2]//x*} ] && mv "${ITEM}" /some/path/tall
done

seanferd · 12-30-2013, 01:08 PM

Quote:

Originally Posted by unSpawn

This snippet is self-contained and small enough for you to be able to run it on say three files and show us the actual output

Code:

set -vx
find /some/path -type f -iname \*.jpg | while read ITEM; do
 DIM=($(identify "${ITEM}")); [ "${DIM[2]}" != "${DIM[2]//x/}" ] || break
 [ ${DIM[2]//x*} -gt ${DIM[2]//x*} ] && mv "${ITEM}" /some/path/tall
done

Hi unSpawn,

Thanks for replying. Sorry for not getting back to you. I ran what you provided on three images, here's the output:

Code:

+ find ./ -type f -iname '*.jpg'
+ read ITEM
+ DIM=($(identify "${ITEM}"))
identify "${ITEM}")
identify "${ITEM}")
identify "${ITEM}"
++ identify ./002.jpg
+ '[' 3648x2736 '!=' 36482736 ']'
+ '[' 3648 -gt 3648 ']'
+ read ITEM
+ DIM=($(identify "${ITEM}"))
identify "${ITEM}")
identify "${ITEM}")
identify "${ITEM}"
++ identify ./003.jpg
+ '[' 3648x2736 '!=' 36482736 ']'
+ '[' 3648 -gt 3648 ']'
+ read ITEM
+ DIM=($(identify "${ITEM}"))
identify "${ITEM}")
identify "${ITEM}")
identify "${ITEM}"
++ identify ./001.jpg
+ '[' 3648x2736 '!=' 36482736 ']'
+ '[' 3648 -gt 3648 ']'
+ read ITEM

unSpawn · 12-30-2013, 01:30 PM

Uh.

Code:

find /some/path -type f -iname \*.jpg | while read ITEM; do DIM=($(identify "${ITEM}"))
 [ ${DIM[2]//*x/} -gt ${DIM[2]//x*/} ] && mv "${ITEM}" /some/path/tall/
done

Don't know what I was thinking...

seanferd · 01-07-2014, 10:33 AM

Quote:

Originally Posted by unSpawn

Uh.

Code:

find /some/path -type f -iname \*.jpg | while read ITEM; do DIM=($(identify "${ITEM}"))
 [ ${DIM[2]//*x/} -gt ${DIM[2]//x*/} ] && mv "${ITEM}" /some/path/tall/
done

Don't know what I was thinking...

This works as expected. Thank you! I'm having a little trouble understanding all that's going on here, though. So, we're finding all of the regular files that end in jpg. The while is running through them all, I assume the read ITEM is like saying 'for ITEM in *.jpg' but based on the input from the find, correct?

Where I'm confused is the beginning of $[DIM[2]// . I assume this is like a sed wherein you just strip the numbers prior to the x in identify, right? If that's true and it works, I don't understand why my original script stopped. You're essentially doing the same -gt that I had, on the same values I was trying before - what gives? Is the output within brackets actually cast as an int or something?

Either way, thanks so much. I like what you've done here, this is way more straightforward and streamlined than what I had previously. Most importantly, it works again!

chrism01 · 01-08-2014, 07:05 PM

See this section on Parameter Expansion and indeed read the whole page; very useful stuff.
http://wiki.bash-hackers.org/syntax/...ch_and_replace