did some changes to pass shellcheck

check proxy

#!/bin/bash

PROXYS='proxy.txt'
PROXY_TYPE='http'
CHECK_URL='https://api.ipify.org?format=json'
MAX_CONNECT=10
GOOD_ARR=()
FAIL_ARR=()
GOOD=0
FAIL=0

# COLORS #
RED='\033[1;31m'
BLUE='\033[1;34m'
TUR='\033[1;36m'
YEL='\033[1;33m'
DEF='\033[0m'
# END OF COLORS #

# GET OPTIONS #
while getopts ":ht:f:g:b:m:u:" OPTION
do
  case $OPTION in
    h)
      echo "Usage: $0 [-h - help] [-t <type> - type of proxy (http - default, socks4, socks5, socks5-hostname (dns throught socks5))] [-f <file> - file with proxy, default proxy.txt] [-g <file> - out file for good proxies] [-b <file> - out file for bad proxies] [-u <url> - url for check proxy, default $CHECK_URL] [-m <sec> - max connect time in second, default 10 sec]"
      echo "proxy format: ip:port:username:password or ip:port"
      exit 0;;
    t)
      PROXY_TYPE="$OPTARG";;
    f)
      PROXYS="$OPTARG";;
    g)
      GOOD_FILE="$OPTARG";;
    b)
      FAIL_FILE="$OPTARG";;
    u)
      CHECK_URL="$OPTARG";;
    m)
      MAX_CONNECT="$OPTARG";;
    *)
     exit 1;;
  esac
done
# END OF GET OPTIONS #

# PROXY TYPE #
if [[ "${PROXY_TYPE}" == "http" ]]
then
  PROXY_TYPE_COMMAND="--proxy"
elif [[  "${PROXY_TYPE}" == "socks4" ]]
then
  PROXY_TYPE_COMMAND="--socks4"
elif [[ "${PROXY_TYPE}" == "socks5" ]]
then
  PROXY_TYPE_COMMAND="--socks5"
elif [[ "${PROXY_TYPE}" == "socks5-hostname" ]]
then
  PROXY_TYPE_COMMAND="--socks5-hostname"
else
  echo -e "${RED}Unknown type proxy. Exit${DEF}\\n"
  exit 1
fi
# END OF PROXY TYPE #

# CHECK CURL IF EXIST #
if ! which curl > /dev/null
then
  echo -e "${RED}curl not found${DEF}\\n"
  exit 1
fi
# END OF CHECK CURL IF EXIST #

# CHECK FILE WITH PROXY IF EXIST #
if [ ! -f "${PROXYS}" ]
then
  echo -e "${RED}File with proxy not found ($PROXYS)${DEF}\\n"
  exit 1
fi
# END OF CHECK FILE WITH PROXY IF EXIST #

# CHECK MAX TIME CONNECT #
RE='^[0-9]+$'
if ! [[ $MAX_CONNECT =~ $RE ]]
then
  echo -e "${RED}Max connect - invalid format${DEF}\\n"
  exit 1
fi
# END OF CHECK MAX TIME CONNECT#

# CHECK PROXY #
for PROXY in $(<"${PROXYS}")
do
  unset USER PASS
  IP=$(echo "${PROXY}" | awk -F: '{print $1}')
  PORT=$(echo "${PROXY}" | awk -F: '{print $2}')
  USER=$(echo "${PROXY}" | awk -F: '{print $3}')
  PASS=$(echo "${PROXY}"| awk -F: '{print $4}')
  
  if [[ $USER && $PASS ]]
  then
    curl -s -m "${MAX_CONNECT}" "${PROXY_TYPE_COMMAND}" "${IP}":"${PORT}" -U "${USER}":"${PASS}" "${CHECK_URL}" > /dev/null
    CHECK=$?
  else
    curl -s -m "${MAX_CONNECT}" "${PROXY_TYPE_COMMAND}" "${IP}":"${PORT}" "${CHECK_URL}" > /dev/null
    CHECK=$?
  fi
  
  if [[ "${CHECK}" -eq 0 ]]
  then
    echo -e "${TUR}$PROXY is good${DEF}"
    GOOD=$((GOOD+1))
    GOOD_ARR+=("${PROXY}")
  else  
    echo -e "${RED}$PROXY is dead${DEF}"
    FAIL=$((FAIL+1))
    FAIL_ARR+=("${PROXY}")
  fi
done
# END OF CHECK PROXY #

# SAVE GOOD PROXY TO FILE #
if [[ "${GOOD_FILE}" ]]
then
  echo -n > "${GOOD_FILE}"
  echo "${GOOD_ARR[@]}" | tr " " "\\n" >> "${GOOD_FILE}"
  echo -e "${TUR}Good proxies save in $GOOD_FILE${DEF}\\n"
fi
# ENF OF SAVE GOOD PROXY TO FILE #

# SAVE FAIL PROXY TO FILE #
if [[ "${FAIL_FILE}" ]]
then
  echo -n > "${FAIL_FILE}"
  echo "${FAIL_ARR[@]}" | tr " " "\\n" >> "${FAIL_FILE}"
  echo -e "${RED}Bad proxies save in $FAIL_FILE${DEF}\\n"
fi
# END OF SAVE FAIL PROXY TO FILE #

echo -e "${BLUE}Good proxy: ${GOOD}${DEF},${RED} bad proxy: ${FAIL}${DEF},${TUR} all: $((GOOD+FAIL))${DEF}\\n"

exit 0