How to loop multiple extensions with upper and lower case letters using for command-CodePudding

I am trying to loop a set of jpg images in a folder. The problem is some of the images have the extension in all lower case letters (.jpg) and others have all capital letters (.JPG).

I am trying to use variable modifiers to change the extensions as the loop progresses.

I figured out how to phrase the for var in LIST part but I can't get the modifiers to replace the extensions correctly.

Essentially I need the jpg files to convert to files with .mpc and .cache extensions.

I end up with files that have names like FILE.jpg.mpc or FILE.JPG.jpg when I need the file to be FILE.mpc and FILE.cache

Here is my function that works great if you only use for i in *.jpg but when you add for i in *.{jpg,JPG} everything falls apart.

Again here is what I have so far.

imow()
{

    clear

    local i DIMENSIONS RANDOM

    # find all jpg files and create temporary cache files from them
    for i in *.{jpg,JPG}
    do
        # create random direcotories in case you are running this function more than once at the same time. it prevents cross-over.
        RANDOM="$(mktemp --directory)"
        "${RANDOM}" 2>/dev/null
        echo -e "\\nCreating two temporary cache files: ${RANDOM}/${i%%.jpg,JPG}.mpc   ${RANDOM}/${i%%.{jpg,JPG}}.cache\\n"
        DIMENSIONS="$(identify -format '%wx%h' "${i}")"
        convert "${i}" -monitor -filter 'Triangle' -define filter:support='2' -thumbnail "${DIMENSIONS}" -strip \
        -unsharp '0.25x0.08 8.3 0.045' -dither None -posterize '136' -quality '82' -define jpeg:fancy-upsampling='off' \
        -define png:compression-filter='5' -define png:compression-level='9' -define png:compression-strategy='1' \
        -define png:exclude-chunk='all' -auto-level -enhance -interlace 'none' -colorspace 'sRGB' "${RANDOM}/${i%%.{jpg,JPG}}.mpc"
        clear
        for i in "${RANDOM}"/*.mpc
        do
            if [ -f "${i}" ]; then
                echo -e "\\nOverwriting original file with optimized self: ${i} >> ${i%%.mpc}.jpg\\n"
                convert "${i}" -monitor "${i%%.mpc}.jpg"
                if [ -f "${i%%.mpc}.jpg" ]; then
                    mv "${i%%.mpc}.jpg" "${PWD}"
                    rm -fr "${RANDOM}"
                    clear
                else
                    clear
                    echo 'Error: Unable to find the optimized image and therefore can'\''t overwrite the original.'
                    echo
                    exit 1
                fi
            fi
        done
    done
}

Like I mentioned if you run it with just the .jpg extension it works great. here is a working example.

imow()
{

    clear

    local i DIMENSIONS RANDOM

    # find all jpg files and create temporary cache files from them
    for i in *.jpg
    do
        # create random directories in case you are running this function more than once at the same time. it prevents cross-over.
        RANDOM="$(mktemp --directory)"
        "${RANDOM}" 2>/dev/null
        echo -e "\\nCreating two temporary cache files: ${RANDOM}/${i%%.jpg}.mpc   ${RANDOM}/${i%%.jpg}.cache\\n"
        DIMENSIONS="$(identify -format '%wx%h' "${i}")"
        convert "${i}" -monitor -filter 'Triangle' -define filter:support='2' -thumbnail "${DIMENSIONS}" -strip \
        -unsharp '0.25x0.08 8.3 0.045' -dither None -posterize '136' -quality '82' -define jpeg:fancy-upsampling='off' \
        -define png:compression-filter='5' -define png:compression-level='9' -define png:compression-strategy='1' \
        -define png:exclude-chunk='all' -auto-level -enhance -interlace 'none' -colorspace 'sRGB' "${RANDOM}/${i%%.jpg}.mpc"
        clear
        for i in "${RANDOM}"/*.mpc
        do
            if [ -f "${i}" ]; then
                echo -e "\\nOverwriting original file with optimized self: ${i} >> ${i%%.mpc}.jpg\\n"
                convert "${i}" -monitor "${i%%.mpc}.jpg"
                if [ -f "${i%%.mpc}.jpg" ]; then
                    mv "${i%%.mpc}.jpg" "${PWD}"
                    rm -fr "${RANDOM}"
                    clear
                else
                    clear
                    echo 'Error: Unable to find the optimized image and therefore can'\''t overwrite the original.'
                    echo
                    exit 1
                fi
            fi
        done
    done

CodePudding user response：

${i%%.jpg,JPG} and ${i%%.{jpg,JPG}} don't do what you want. The first tries to remove the exact suffix .jpg,JPG, and the second tries to remove the exact suffix .{jpg,JPG}. Since the suffix is guaranteed to be either .jpg or .JPG at that point in the code, ${i%.*} is a safe alternative.

CodePudding user response：

As I read it, your function already overwrites original .jpg files, but hardcodes a lowercase .jpg which leaves the old .JPG files lying around. I'd just formalize the conversion to lowercase unless there's some specific reason you shouldn't/can't.

Get rid of those broken uppercase variables, and your inner loop using the same loop var as the outer loop, etc. I moved some stuff around, but don't have imagemagick installed so this is a freehand edit; I trust someone will point out any glaring logic errors as I can't really test it the way I'd like.

I explicitly test the imagemagick return code to simplify a bit, and added a test to make sure the mv succeeded. If the original file's extension is not all lowercase, it now should be removed once the optimized file is staged.

I also removed the clear commands that were erasing output you had just explicitly logged in favor of sending convert spam to logs that get wiped unless there was a problem.

imow() {
  local orig mpc new dim rc tdir boilerplate
  tdir="$(mktemp --directory)" 
  boilerplate=( -monitor -filter 'Triangle' -define filter:support='2' 
    -strip -unsharp '0.25x0.08 8.3 0.045' -dither None -posterize '136'
    -quality '82' -define jpeg:fancy-upsampling='off' 
    -define png:compression-filter='5' -define png:compression-level='9'
    -define png:compression-strategy='1' -define png:exclude-chunk='all'
    -auto-level -enhance -interlace 'none' -colorspace 'sRGB' )
  for orig in *.[Jj][Pp][Gg]
  do dim="$(identify -format '%wx%h' "$orig")"
     if convert "$orig" "${boilerplate[@]}" -thumbnail "$dim" "${tdir}/${orig%.???}.mpc" > "$tdir/convert-mpc.out"
     then for mpc in "${tdir}"/*.mpc
          do new="${mpc%.mpc}.jpg"
             if convert "$mpc" -monitor "$new" > "$tdir/convert-jpg.out"
             then echo "Replacing $orig with optimized version $new"
                  if mv "$new" "$PWD"
                  then [[ "$orig" == "$new" ]] || rm -f "$orig"
                       rm -fr "${tdir:?safety check}/*.*" # can't expand to rm -fr /*
                  else rc=$?;
                       echo "Cannot mv '$new' to '$PWD': error $rc; aborting" >&2
                       exit $rc
                  fi
        else rc=$?
                  echo "convert error $rc on $mpc; c.f. $tdir - aborting." >&2
                  exit $rc
             fi
          done
     else rc=$?
          echo "convert error $rc on $orig; c.f. $tdir - aborting." >&2
          exit $rc
     fi
  done
  rm -fr "$tdir"
}

*.[Jj][Pp][Gg] with match any combination of upper/lower on the extension.

Make sure you test and modify to suit your needs.
Good luck.