Build a command-line SMS sender in Go — useful for scripts, cron jobs, and CI/CD pipelines

CLI SMS Tool with Go

This tutorial builds a standalone Go CLI that sends SMS messages from your terminal, shell scripts, and CI/CD pipelines.

# Send a single message
sms-send -to +244923000000 -msg "Deploy to production succeeded"

# Notify multiple recipients
sms-send -to +244923000000,+244912000001 -msg "Nightly backup completed"

# Read message from stdin (pipe-friendly)
echo "Disk usage at 90%" | sms-send -to +244923000000

Prerequisites

Go 1.21+
A CastBrick API key from the dashboard

Setup

mkdir sms-send && cd sms-send
go mod init sms-send
go get github.com/IldySilva/castbrick-go

The code

Create main.go:

package main

import (
	"bufio"
	"context"
	"flag"
	"fmt"
	"io"
	"os"
	"strings"
	"time"

	"github.com/IldySilva/castbrick-go/castbrick"
)

func main() {
	to := flag.String("to", "", "Recipient phone number(s), comma-separated (e.g. +244923000000,+244912000001)")
	msg := flag.String("msg", "", "Message text. Omit to read from stdin.")
	sender := flag.String("sender", "", "Optional sender ID (e.g. MyApp)")
	flag.Parse()

	if *to == "" {
		fmt.Fprintln(os.Stderr, "error: -to is required")
		flag.Usage()
		os.Exit(1)
	}

	recipients := splitRecipients(*to)
	content := *msg

	// Read from stdin if no -msg flag provided
	if content == "" {
		content = readStdin()
	}

	if strings.TrimSpace(content) == "" {
		fmt.Fprintln(os.Stderr, "error: message is empty")
		os.Exit(1)
	}

	apiKey := os.Getenv("CASTBRICK_API_KEY")
	if apiKey == "" {
		fmt.Fprintln(os.Stderr, "error: CASTBRICK_API_KEY environment variable is not set")
		os.Exit(1)
	}

	cb := castbrick.New(apiKey)

	ctx, cancel := context.WithTimeout(context.Background(), 15*time.Second)
	defer cancel()

	opts := castbrick.SendSmsOptions{
		To:      recipients,
		Content: content,
	}
	if *sender != "" {
		opts.SenderID = *sender
	}

	result, err := cb.SMS.Send(ctx, opts)
	if err != nil {
		fmt.Fprintf(os.Stderr, "error: %v\n", err)
		os.Exit(1)
	}

	fmt.Printf("Sent to %d recipient(s). Message ID: %s\n", result.RecipientCount, result.MessageID)
}

func splitRecipients(s string) []string {
	parts := strings.Split(s, ",")
	out := make([]string, 0, len(parts))
	for _, p := range parts {
		if t := strings.TrimSpace(p); t != "" {
			out = append(out, t)
		}
	}
	return out
}

func readStdin() string {
	stat, _ := os.Stdin.Stat()
	if (stat.Mode() & os.ModeCharDevice) != 0 {
		return "" // nothing piped
	}
	data, _ := io.ReadAll(bufio.NewReader(os.Stdin))
	return strings.TrimSpace(string(data))
}

Build and install

go build -o sms-send .

# Install globally (optional)
go install .

Export your API key:

export CASTBRICK_API_KEY=your_api_key_here

Usage examples

# Basic send
./sms-send -to +244923000000 -msg "Hello from the terminal"

# Multiple recipients
./sms-send -to "+244923000000,+244912000001" -msg "Server restarted successfully"

# Custom sender ID
./sms-send -to +244923000000 -msg "Deployment done" -sender "CI/CD"

# Pipe from a command
df -h | grep "90%" | ./sms-send -to +244923000000

# Pipe a file
cat report.txt | ./sms-send -to +244923000000

Using in shell scripts

#!/bin/bash
set -e

# Run your task
./run-backup.sh

STATUS=$?

if [ $STATUS -eq 0 ]; then
  ./sms-send -to +244923000000 -msg "Backup completed successfully at $(date)"
else
  ./sms-send -to "+244923000000,+244912000001" -msg "BACKUP FAILED with exit code $STATUS — check logs"
fi

Using in a Cron job

# Edit crontab
crontab -e

# Send a daily report at 8am
0 8 * * * CASTBRICK_API_KEY=your_key /usr/local/bin/sms-send -to +244923000000 -msg "Good morning! Daily report: $(uptime)"

Using in CI/CD (GitHub Actions example)

- name: Notify team on deploy
  env:
    CASTBRICK_API_KEY: ${{ secrets.CASTBRICK_API_KEY }}
  run: |
    ./sms-send -to ${{ secrets.ONCALL_PHONE }} \
      -msg "Deploy of ${{ github.repository }}@${{ github.sha }} succeeded" \
      -sender "GitHub"

Store your API key as a secret in your CI/CD platform — never hardcode it in scripts or commit it to version control.

Next steps

Go SDK reference — scheduling, contacts, broadcasts
Webhooks — confirm delivery status programmatically
API overview — call the REST API directly if you need custom integrations

CLI SMS Tool with Go

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