slack_send_pm.sh

#!/bin/bash
set -e

# Send a private message to someone on slack
# from the command line.

# Print a usage message and exit.
usage(){
	local name=$(basename "$0")

	cat >&2 <<-EOF
	${name} [user] [message]

	You will also need to set \$SLACK_TOKEN for authentication.
	You can generate a Web Api Token here: https://api.slack.com/web
	EOF
	exit 1
}

[ "$SLACK_TOKEN" ] || usage

# Print usage with --help or -h
if [ "$#" -lt 2 ]; then
	usage;
fi

nick_to_userid(){
	local nick=$1

	# get the users
	local users=$(curl -sSL -X POST \
		--data-urlencode "token=${SLACK_TOKEN}" \
		--data-urlencode "presence=1" \
		https://slack.com/api/users.list | jq '.members')

	# find the user we want
	local user=$(echo $users | jq '.[] | select(.name == "'${nick}'")')

	if [[ -z "$user" ]]; then
		echo "Could not find user with nick ${nick}."
		return 1
	fi

	# set presence and userid
	presence=$(echo $user | jq --raw-output '.presence')
	userid=$(echo $user | jq --raw-output '.id')

	echo "Sending private message to:"
	echo "  User:    ${nick}"
	echo "  Status:  ${presence}"
}

user_to_channelid(){
	local user=$1

	# get the im channels
	local channels=$(curl -sSL -X POST \
		--data-urlencode "token=${SLACK_TOKEN}" \
		https://slack.com/api/im.list | jq '.ims')

	# find the user we want
	local channel=$(echo $channels | jq '.[] | select(.user == "'${user}'")')

	if [[ -z "$channel" ]]; then
		echo "Could not find im channel with user id ${user}."
		return 1
	fi

	# set channelid
	channelid=$(echo $channel | jq --raw-output '.id')
}

send_message(){
	local nick=$1
	local message=${*:2}

	# get the users id
	nick_to_userid ${nick}

	# get the channel id for the im with this user
	user_to_channelid ${userid}

	local postresp=$(curl -sSL -X POST \
		--data-urlencode "token=${SLACK_TOKEN}" \
		--data-urlencode "channel=${channelid}" \
		--data-urlencode "text=${message}" \
		--data-urlencode "as_user=1" \
		https://slack.com/api/chat.postMessage)

	echo $postresp | jq .
}

send_message $@