added 'Shell functions'

- signed-off-by: trimstray <trimstray@gmail.com>

README.md

@@ -88,6 +88,7 @@ Only main chapters:
 - **[Your daily knowledge and news](#your-daily-knowledge-and-news-toc)**
 - **[Other Cheat Sheets](#other-cheat-sheets-toc)**
 - **[One-liners](#one-liners-toc)**
+- **[Shell functions](#shell-functions-toc)**
 
 ## :trident:  The Book of Secret Knowledge (Chapters)
 
@@ -2900,3 +2901,86 @@ grep -v ^[[:space:]]*# filename
 ```bash
 egrep -v '#|^$' filename
 ```
+
+#### Shell functions &nbsp;[<sup>[TOC]</sup>](#anger-table-of-contents)
+
+###### Domain resolve
+
+```bash
+# Dependencies:
+#   - curl
+#   - jq
+
+function DomainResolve() {
+
+  local _host="$1"
+
+  local _curl_base="curl --request GET"
+  local _timeout="15"
+
+  _host_ip=$($_curl_base -ks -m "$_timeout" "https://dns.google.com/resolve?name=${_host}&type=A" | \
+  jq '.Answer[0].data' | tr -d "\"" 2>/dev/null)
+
+  if [[ -z "$_host_ip" ]] || [[ "$_host_ip" == "null" ]] ; then
+
+    echo -en "Unsuccessful domain name resolution.\\n"
+
+  else
+
+    echo -en "$_host > $_host_ip\\n"
+
+  fi
+
+}
+```
+
+Example:
+
+```bash
+shell> DomainResolve nmap.org
+nmap.org > 45.33.49.119
+
+shell> DomainResolve nmap.orgs
+Unsuccessful domain name resolution.
+```
+
+###### Get ASN
+
+```bash
+# Dependencies:
+#   - curl
+#   - python
+
+function GetASN() {
+
+  local _ip="$1"
+
+  local _curl_base="curl --request GET"
+  local _timeout="15"
+
+  _asn=$($_curl_base -ks -m "$_timeout" "http://ip-api.com/json/${_ip}" | python -c 'import sys, json; print json.load(sys.stdin)["as"]' 2>/dev/null)
+
+  _state=$(echo $?)
+
+  if [[ -z "$_ip" ]] || [[ "$_ip" == "null" ]] || [[ "$_state" -ne 0 ]]; then
+
+    echo -en "Unsuccessful ASN gathering.\\n"
+
+  else
+
+    echo -en "$_ip > $_asn\\n"
+
+  fi
+
+}
+```
+
+Example:
+
+```bash
+shell> GetASN 1.1.1.1
+1.1.1.1 > AS13335 Cloudflare, Inc.
+
+shell> GetASN 0.0.0.0
+Unsuccessful ASN gathering.
+```