Consider fixing shellcheck issues

[shuuryou]

There are some minor issues when running ShellCheck on the script. The biggest ones (using features not available on POSIX sh) can be fixed by changing the shebang from #!/bin/sh to e.g. #!/usr/bin/env bash

What follows is the full ShellCheck output so you can get an idea. This is after I changed the interpreter from sh to bash. I understand that majority of the problems it finds are subjective, but I still figured I'd let you know. Feel free to close the issue as WONTFIX etc. if you don't care.

# shellcheck hetznerddns.sh

In hetznerddns.sh line 46:
  echo ${1}: Record_Name: ${record_name} : ${2}
       ^--^ SC2086 (info): Double quote to prevent globbing and word splitting.
                          ^------------^ SC2086 (info): Double quote to prevent globbing and word splitting.
                                           ^--^ SC2086 (info): Double quote to prevent globbing and word splitting.

Did you mean:
  echo "${1}": Record_Name: "${record_name}" : "${2}"


In hetznerddns.sh line 81:
          --header 'Auth-API-Token: '${auth_api_token})
                                     ^---------------^ SC2086 (info): Double quote to prevent globbing and word splitting.

Did you mean:
          --header 'Auth-API-Token: '"${auth_api_token}")


In hetznerddns.sh line 84:
if [[ "$(echo ${zone_info} | jq --raw-output '.zones[] | select(.name=="'${zone_name}'") | .id')" = "" && "$(echo ${zone_info} | jq --raw-output '.zones[] | select(.id=="'${zone_id}'") | .name')" = "" ]]; then
              ^----------^ SC2086 (info): Double quote to prevent globbing and word splitting.
                                                                         ^----------^ SC2086 (info): Double quote to prevent globbing and word splitting.
                                                                                                                  ^----------^ SC2086 (info): Double quote to prevent globbing and word splitting.
                                                                                                                                                                           ^--------^ SC2086 (info): Double quote to prevent globbing and word splitting.

Did you mean:
if [[ "$(echo "${zone_info}" | jq --raw-output '.zones[] | select(.name=="'"${zone_name}"'") | .id')" = "" && "$(echo "${zone_info}" | jq --raw-output '.zones[] | select(.id=="'"${zone_id}"'") | .name')" = "" ]]; then


In hetznerddns.sh line 93:
  zone_id=$(echo ${zone_info} | jq --raw-output '.zones[] | select(.name=="'${zone_name}'") | .id')
                 ^----------^ SC2086 (info): Double quote to prevent globbing and word splitting.
                                                                            ^----------^ SC2086 (info): Double quote to prevent globbing and word splitting.

Did you mean:
  zone_id=$(echo "${zone_info}" | jq --raw-output '.zones[] | select(.name=="'"${zone_name}"'") | .id')


In hetznerddns.sh line 98:
  zone_name=$(echo ${zone_info} | jq --raw-output '.zones[] | select(.id=="'${zone_id}'") | .name')
                   ^----------^ SC2086 (info): Double quote to prevent globbing and word splitting.
                                                                            ^--------^ SC2086 (info): Double quote to prevent globbing and word splitting.

Did you mean:
  zone_name=$(echo "${zone_info}" | jq --raw-output '.zones[] | select(.id=="'"${zone_id}"'") | .name')


In hetznerddns.sh line 137:
                 --request GET 'https://dns.hetzner.com/api/v1/records?zone_id='${zone_id} \
                                                                                ^--------^ SC2086 (info): Double quote to prevent globbing and word splitting.

Did you mean:
                 --request GET 'https://dns.hetzner.com/api/v1/records?zone_id='"${zone_id}" \


In hetznerddns.sh line 138:
                 --header 'Auth-API-Token: '${auth_api_token})
                                            ^---------------^ SC2086 (info): Double quote to prevent globbing and word splitting.

Did you mean:
                 --header 'Auth-API-Token: '"${auth_api_token}")


In hetznerddns.sh line 145:
    record_id=$(echo ${record_zone} | jq | sed '$d' | jq --raw-output '.records[] | select(.type == "'${record_type}'") | select(.name == "'${record_name}'") | .id')
                     ^------------^ SC2086 (info): Double quote to prevent globbing and word splitting.
                                                                                                      ^------------^ SC2086 (info): Double quote to prevent globbing and word splitting.
                                                                                                                                            ^------------^ SC2086 (info): Double quote to prevent globbing and word splitting.

Did you mean:
    record_id=$(echo "${record_zone}" | jq | sed '$d' | jq --raw-output '.records[] | select(.type == "'"${record_type}"'") | select(.name == "'"${record_name}"'") | .id')


In hetznerddns.sh line 156:
       -H 'Auth-API-Token: '${auth_api_token} \
                            ^---------------^ SC2086 (info): Double quote to prevent globbing and word splitting.

Did you mean:
       -H 'Auth-API-Token: '"${auth_api_token}" \


In hetznerddns.sh line 158:
          "value": "'${cur_pub_addr}'",
                     ^-------------^ SC2086 (info): Double quote to prevent globbing and word splitting.

Did you mean:
          "value": "'"${cur_pub_addr}"'",


In hetznerddns.sh line 159:
          "ttl": '${record_ttl}',
                  ^-----------^ SC2086 (info): Double quote to prevent globbing and word splitting.

Did you mean:
          "ttl": '"${record_ttl}"',


In hetznerddns.sh line 160:
          "type": "'${record_type}'",
                    ^------------^ SC2086 (info): Double quote to prevent globbing and word splitting.

Did you mean:
          "type": "'"${record_type}"'",


In hetznerddns.sh line 161:
          "name": "'${record_name}'",
                    ^------------^ SC2086 (info): Double quote to prevent globbing and word splitting.

Did you mean:
          "name": "'"${record_name}"'",


In hetznerddns.sh line 162:
          "zone_id": "'${zone_id}'"
                       ^--------^ SC2086 (info): Double quote to prevent globbing and word splitting.

Did you mean:
          "zone_id": "'"${zone_id}"'"


In hetznerddns.sh line 166:
  cur_dyn_addr=`curl -s "https://dns.hetzner.com/api/v1/records/${record_id}" -H 'Auth-API-Token: '${auth_api_token} | jq --raw-output '.record.value'`
               ^-- SC2006 (style): Use $(...) notation instead of legacy backticks `...`.
                                                                                                   ^---------------^ SC2086 (info): Double quote to prevent globbing and word splitting.

Did you mean:
  cur_dyn_addr=$(curl -s "https://dns.hetzner.com/api/v1/records/${record_id}" -H 'Auth-API-Token: '"${auth_api_token}" | jq --raw-output '.record.value')


In hetznerddns.sh line 171:
  if [[ $cur_pub_addr == $cur_dyn_addr ]]; then
                         ^-----------^ SC2053 (warning): Quote the right-hand side of == in [[ ]] to prevent glob matching.


In hetznerddns.sh line 178:
         -H 'Auth-API-Token: '${auth_api_token} \
                              ^---------------^ SC2086 (info): Double quote to prevent globbing and word splitting.

Did you mean:
         -H 'Auth-API-Token: '"${auth_api_token}" \


In hetznerddns.sh line 180:
           "value": "'${cur_pub_addr}'",
                      ^-------------^ SC2086 (info): Double quote to prevent globbing and word splitting.

Did you mean:
           "value": "'"${cur_pub_addr}"'",


In hetznerddns.sh line 181:
           "ttl": '${record_ttl}',
                   ^-----------^ SC2086 (info): Double quote to prevent globbing and word splitting.

Did you mean:
           "ttl": '"${record_ttl}"',


In hetznerddns.sh line 182:
           "type": "'${record_type}'",
                     ^------------^ SC2086 (info): Double quote to prevent globbing and word splitting.

Did you mean:
           "type": "'"${record_type}"'",


In hetznerddns.sh line 183:
            "name": "'${record_name}'",
                      ^------------^ SC2086 (info): Double quote to prevent globbing and word splitting.

Did you mean:
            "name": "'"${record_name}"'",


In hetznerddns.sh line 184:
           "zone_id": "'${zone_id}'"
                        ^--------^ SC2086 (info): Double quote to prevent globbing and word splitting.

Did you mean:
           "zone_id": "'"${zone_id}"'"


In hetznerddns.sh line 186:
    if [[ $? != 0 ]]; then
          ^-- SC2181 (style): Check exit code directly with e.g. 'if ! mycmd;', not indirectly with $?.

For more information:
  https://www.shellcheck.net/wiki/SC2053 -- Quote the right-hand side of == i...
  https://www.shellcheck.net/wiki/SC2086 -- Double quote to prevent globbing ...
  https://www.shellcheck.net/wiki/SC2006 -- Use $(...) notation instead of le...