Shell/Bash script for sending slack messages.

slack.sh

#!/usr/bin/env bash
####################################################################################
# Slack Bash console script for sending messages.
####################################################################################
# Installation
#    $ curl -s https://gist.githubusercontent.com/andkirby/67a774513215d7ba06384186dd441d9e/raw --output /usr/bin/slack
#    $ chmod +x /usr/bin/slack
####################################################################################
# USAGE
# Send message to slack channel/user
#   Send a message to the channel #ch-01
#     $ slack '#ch-01' 'Some message here.'
#
#   Send a message to the channel #ch-01 and user @me.
#     $ slack '#ch-01,@me' MESSAGE
#
#   Send a message to the default channel (it must be declared in APP_SLACK_CHANNEL).
#     $ slack  MESSAGE
#
# VARIABLES
#
# Please declare environment variables:
#   - APP_SLACK_WEBHOOK
#   - APP_SLACK_CHANNEL (optional)
#   - APP_SLACK_USERNAME (optional)
#   - APP_SLACK_ICON_EMOJI (optional)
# You may also declare them in ~/.slackrc file.
####################################################################################

set -o pipefail
set -o errexit
set -o nounset
#set -o xtrace

init_params() {
  # you may declare ENV vars in /etc/profile.d/slack.sh
  if [ -z "${APP_SLACK_WEBHOOK:-}" ]; then
    echo 'error: Please configure Slack environment variable: ' > /dev/stderr
    echo '  APP_SLACK_WEBHOOK' > /dev/stderr
    exit 2
  fi

  APP_SLACK_USERNAME=${APP_SLACK_USERNAME:-$(hostname | cut -d '.' -f 1)}

  APP_SLACK_ICON_EMOJI=${APP_SLACK_ICON_EMOJI:-:slack:}
  if [ -z "${1:-}" ]; then
    echo 'error: Missed required arguments.' > /dev/stderr
    echo 'note: Please follow this example:' > /dev/stderr
    echo '  $ slack.sh "#CHANNEL1,CHANNEL2" Some message here. ' > /dev/stderr
    exit 3
  fi

  slack_channels=(${APP_SLACK_CHANNEL:-})
  if [ "${1::1}" == '#' ] || [ "${1::1}" == '@' ]; then
    # explode by comma
    IFS=',' read -r -a slack_channels <<< "${1}"
    shift
  fi
  slack_message=${@}
}


send_message() {
  local channel=${1}
  echo 'Sending to '${channel}'...'
  curl --silent --data-urlencode \
    "$(printf 'payload={"text": "%s", "channel": "%s", "username": "%s", "as_user": "true", "link_names": "true", "icon_emoji": "%s" }' \
        "${slack_message}" \
        "${channel}" \
        "${APP_SLACK_USERNAME}" \
        "${APP_SLACK_ICON_EMOJI}" \
    )" \
    ${APP_SLACK_WEBHOOK} || true
  echo
}

send_message_to_channels() {
  for channel in "${slack_channels[@]:-}"; do
    send_message "${channel}"
  done
}

slack() {
  # Set magic variables for current file & dir
  __dir="$(cd "$(dirname "${BASH_SOURCE[0]}")" && pwd)"
  __file="${__dir}/$(basename "${BASH_SOURCE[0]}")"
  readonly __dir __file

  cd ${__dir}

  if [ -f $(cd; pwd)/.slackrc ]; then
    . $(cd; pwd)/.slackrc
  fi

  declare -a slack_channels

  init_params ${@}
  send_message_to_channels
}

if [ "${BASH_SOURCE[0]:-}" != "${0}" ]; then
  export -f slack
else
  slack ${@}
  exit $?
fi

So, is there some patch to improve the script? :)

You should consider implementing multiple types of posting. eg. as an attachment.

how can i send file?

@rasperepodvipodvert,
you should update data to send
https://api.slack.com/docs/message-attachments

Fantastic

how can i send file?

Maybe put a file on s3 and send it as link. Could be a quick solution :)

On OS X the BSD version of cut complains:

cut: illegal option -- -

If you replace L43 with this one, then it would support both BSD and GNU cut:

APP_SLACK_USERNAME=${APP_SLACK_USERNAME:-$(hostname | cut -d '.' -f 1)}

I try next command but didn't work:

a=123
slack '${a}'

I expected the output 123, but the output was ${a}

@jotabf, it doesn't in this bash in this way for single quotes. It should be in double quotes or whithout ones (in case a value doesn't have spaces, it can be tricky for arguments.)

@siso, fixed. Thanks for this note.

Hello All,

Could anyone help me please to get emails on outlook for specific slack channels with some specific content like "failures"
and that should trigger twice a day at some specific timings.
Thanks in Advance

@Lalit-1219, it's not about this script definitely. ;)
You may try to adjust nofication settings. I remember there is "keywords" feature.

hi @andkirby

I want to ask, why can I sent from grep command?

my sh script like this :

#!/bin/bash
message=$(grep AUDIT audit.txt)
slack ${message}

if I execute this, I always get this error:

/home/ubuntu# ./test_sent.sh
Sending to ...
invalid_payload

can you solve this?

Hi @farisalfa,

The only one who can solve it that's you. ;)

I guess, that's not about script but about Bash scripting knowledge.
Just double checked — it works fine. Think about double quotes for your variable.

Thanks bro', u saved my night 👊🏻

Just an insight to those facing issues with /usr/bin/slack due to permission accessing to /usr/bin, you can move the script under usr/local/bin/slack.

So that the two commands to run will be:

curl -s https://gist.githubusercontent.com/andkirby/67a774513215d7ba06384186dd441d9e/raw --output /usr/local/bin/slack

chmod +x /usr/local/bin/slack

hope it helps 👍
great script @andkirby 💪

Hi,

when sending a message in this way:
slack.sh ":arrow_right: data seeding"
emoji appears as text and it is not rendered, what am I doing wrong ?
Thanks!

emoji appears as text and it is not rendered, what am I doing wrong ?

@jmhostalet, I assume, they added mrkdwn type for that.
https://api.slack.com/reference/surfaces/formatting#basics

great script @andkirby 💪

@d4r1091, it's a pleasure to know it. ;)

@jmhostalet, just double check it. It works with emoji. According to off-docs mrkdwn=true always.

hi @andkirby

I want to ask, why can I sent from grep command?

my sh script like this :

#!/bin/bash
message=$(grep AUDIT audit.txt)
slack ${message}

if I execute this, I always get this error:

/home/ubuntu# ./test_sent.sh
Sending to ...
invalid_payload

can you solve this?