slack_notification_test.sh

#!/bin/bash

to_ref='00000000000000000000000000'

channel='private-group'
username='stash'
text="*branch name* has new commits by *user name*"
icon=':stash:'

attachments=''
  [[ $to_ref =~ ^0+$ ]] && continue
  branch='master'
  url="repo url"
  to_ref_pref=`echo $to_ref | cut -c 1-10`
  link=`printf '<%s/commits/%s|%s>' $url $to_ref $to_ref_pref`
  message=`git log --format=%B -n 1 ${to_ref}`
  title="[_${branch}_] ${link}: $message"
  attachments="$attachments{
    \"fallback\":\"$title\",
    \"text\": \"$title\",
    \"color\":\"#4083C4\",
    \"mrkdwn_in\": [\"text\"]
  },"

payload="payload={
\"channel\":\"$channel\",
\"username\":\"$username\",
\"text\":\"$text\",
\"icon_emoji\":\"$icon\",
\"attachments\":[${attachments%?}]
}
"

curl -X POST --data-urlencode "$payload" "incoming-webhook url"