Slice images for making comic

slice.sh

#!/bin/bash

slice() {
  DIR=$(gm identify -format %d "$1")
  FILENAME=$(gm identify -format %t "$1")
  EXTENSION=$(gm identify -format %e "$1")
  WIDTH=$(gm identify -format %w "$1")
  OFFSET=$((WIDTH/2))
  if [ "$DIR" ]; then
    FILENAME="${DIR}/${FILENAME}"
  fi

  gm convert -crop 50x100+0+0% "$1" "${FILENAME}_2.${EXTENSION}"
  gm convert -crop 50x100+${OFFSET}+0% "$1" "${FILENAME}_1.${EXTENSION}"
}

slice_all() {
  for file in "$1"/*$2; do
    slice "$file"
    unlink "$file"
  done
}

if [[ -d "$1" ]]; then
  slice_all "$1" $2
elif [[ -f "$1" ]]; then
  slice "$1"
  unlink "$1"
else
  exit 1
fi