Bun Shell Has a Free API: Write Shell Scripts in JavaScript That Actually Work

#bunjs #javascript #shell #scripting

Bash scripts break on spaces in filenames. Node's child_process is verbose. Bun Shell gives you shell scripting in JavaScript — safe, cross-platform, and actually readable.

What Is Bun Shell?

Bun Shell (Bun.$) is a shell-like API built into Bun. It combines the convenience of shell scripting with the safety of JavaScript.

import { $ } from "bun"

// Run shell commands
await $`echo "Hello from Bun Shell!"`

// Capture output
const result = await $`ls -la`.text()
console.log(result)

// Pipe commands
await $`cat data.json | jq '.users[]'`

// Template literals are safe (auto-escaped!)
const filename = "file with spaces.txt"
await $`cat ${filename}`  // Works! No quoting issues

// Environment variables
await $`echo $HOME`

Safe by Default

// Bash: user input can break everything
// rm -rf $user_input  ← if user_input is "/ --no-preserve-root", disaster

// Bun Shell: template variables are auto-escaped
const userInput = "/ --no-preserve-root"
await $`echo ${userInput}`  // Prints literally, doesn't execute

Practical Scripts

// Deploy script
const branch = await $`git branch --show-current`.text()
console.log(\`Deploying \${branch.trim()}...\`)

await $`npm run build`
await $`docker build -t myapp:latest .`
await $`docker push myapp:latest`

console.log("Deployed!")

// File processing
import { $ } from "bun"
import { Glob } from "bun"

const glob = new Glob("**/*.ts")
for await (const file of glob.scan(".")) {
  const lines = await $`wc -l ${file}`.text()
  console.log(lines.trim())
}

// Error handling
try {
  await $`curl https://api.example.com/health`.quiet()
} catch (e) {
  console.error(\`Health check failed: \${e.exitCode}\`)
  await $`systemctl restart myapp`
}