Script to download images from Gelbooru.

gel

#!/bin/sh
# Dependencies: curl, wget, jq

escape_special_url_characters() { # print arguments after escaping special URL characters in them
  echo $@ |
    sed 's/%/%25/g; s/\$/%24/g; s/&/%26/g; s/\+/%2B/g; s/,/%2C/g;
         s/\//%2F/g; s/:/%3A/g; s/;/%3B/g; s/=/%3D/g; s/\?/%3F/g;
         s/@/%40/g; s/ /%20/g; s/"/%22/g; s/</%3C/g; s/>/%3E/g;
         s/#/%23/g; s/{/%7B/g; s/}/%7D/g; s/|/%7C/g; s/\\/%5C/g;
         s/\^/%5E/g; s/~/%7E/g; s/\[/%5B/g; s/]/%5D/g; s/`/%60/g;'
}

limit=1
if [ $GELDIR ]; then
  dir=$GELDIR
elif [ -d ~/Downloads ]; then
  dir=~/Downloads
else
  dir=~/.gel
fi
while getopts :hndk:u:i:l:p:c:o: c; do
  case $c in
    h) echo 'Usage: gelposts [-hnd] [-i ID] [-k API_KEY] [-u USER_ID] [-l LIMIT] [-p PID] [-c CID] [-o DIR] [TAG...]'
       echo 'Download images from Gelbooru.'
       echo
       echo '  -h        display this help and exit'
       echo '  -n        clear the download directory before downloading'
       echo '  -d        download images of deleted posts'
       echo '  -l=LIMIT  download only LIMIT images'
       echo '  -p=PID    specify the post offset (page number)'
       echo '  -c=CID    specify the change ID'
       echo '  -o=DIR    download images to DIR'
       echo
       echo 'If DIR is not specified, $GELDIR is used.'
       echo 'If $GELDIR is unset, ~/Downloads is used.'
       echo 'If ~/Downloads is not a directory, ~/.gel is created (if necessary) and used.'
       exit;;
    n) clean=1;;
    d) deleted_param='&deleted=show';;
    k) api_key_param="&api_key=`escape_special_url_characters $OPTARG`";;
    u) user_id_param="&user_id=`escape_special_url_characters $OPTARG`";;
    i) id_param="&id=`escape_special_url_characters $OPTARG`";;
    l) limit=`escape_special_url_characters $OPTARG`;;
    p) pid_param="&pid=`escape_special_url_characters $OPTARG`";;
    c) cid_param="&cid=`escape_special_url_characters $OPTARG`";;
    o) dir=$OPTARG;;
  esac
done
limit_param="&limit=$limit"
if [ $limit -gt 0 ]; then
  shift $(($OPTIND - 1))
  tags_param="&tags=`escape_special_url_characters $@`"
  mkdir -p $dir
  echo Retrieving post info...
  res=`curl -s "https://gelbooru.com/index.php?page=dapi&s=post&q=index&json=1$api_key_param$user_id_param$id_param$limit_param$pid_param$deleted_param$cid_param$tags_param"`
  i=0
  len=`echo $res | jq length`
  echo Selecting $dir
  if [ $clean -a "`ls $dir`" ]; then
    echo Clearing directory
    rm -r $dir/*
  fi
  if [ $len -gt 0 ]; then
    echo Downloading $len image`[ $len -gt 1 ] && echo s`
  else
    echo Nothing to download
  fi
  while [ $i -lt $len ]; do
    post=`echo $res | jq ".[$i]"`
    url=`echo $post | jq -r .file_url`
    basename=`echo $post | jq -r .image`
    path=$dir/$basename
    exists=`[ -e $path ] && echo 1`
    echo [$((i + 1))/$len] $basename `[ $exists ] && echo '(skipped)'`
    if [ ! $exists ]; then
      wget -q --show-progress -O $path $url
    fi
    ((i++))
  done
fi