ob/bin/index.js

OB (The Second Terminal Printer) - A lightweight server-client tool for real-time terminal logging and progress display via Unix sockets. Ideal for CLI apps needing dynamic output management.

#!/usr/bin/env node
/*
            .-. .-')   
            \  ( OO )  
 .-'),-----. ;-----.\  
( OO'  .-.  '| .-.  |  
/   |  | |  || '-' /_) 
\_) |  |\|  || .-. `.  
  \ |  | |  || |  \  | 
   `'  '-'  '| '--'  / 2025.07.14
     `-----' `------'  The second terminal printer
*/
import net from 'net'
import fs from 'fs'
import os from 'os'
import util from 'util'

const SOCKET_PATH = os.platform() === 'win32' ? '\\\\.\\pipe\\log-pipe' : '/tmp/log.sock'

function styleText(format, text) {
  const codes = {
    red: '\x1b[31m',
    bgBlue: '\x1b[44m',
    bold: '\x1b[1m',
    reset: '\x1b[0m',
  }
  const styles = Array.isArray(format) ? format : [format]
  return styles.map((f) => codes[f]).join('') + text + codes.reset
}

function parseStr(string) {
  try {
    const arr = JSON.parse(string)
    if (!Array.isArray(arr)) {
      return 'Error: Invalid string.'
    }
    return arr
  } catch (error) {
    return new Error(error).toString()
  }
}

function logger(string) {
  if (string.startsWith('Error')) {
    console.log(styleText('red', string))
    return
  }
  const result = parseStr(string)
  if (typeof result == 'string') {
    console.log(styleText('red', result))
    return
  }
  const args = result.map((item) =>
    util.inspect(item, {
      depth: null,
      colors: true,
      compact: false,
    }),
  )
  console.log(...args)
}

function startLogServer() {
  if (os.platform() !== 'win32') {
    try {
      if (fs.existsSync(SOCKET_PATH)) {
        fs.unlinkSync(SOCKET_PATH)
        console.log(`Cleaned up existing socket file: ${SOCKET_PATH}`)
      }
    } catch (err) {
      console.error(`Failed to clean up socket file: ${err.message}`)
    }
  }

  const server = net.createServer((socket) => {
    socket.on('data', (data) => logger(data.toString()))
    socket.on('end', () => {})
  })

  server.listen(SOCKET_PATH, () => {
    console.log(`Log server listening on ${SOCKET_PATH}`)
    console.log('Press Ctrl+C to stop.')
  })

  server.on('error', (err) => {
    console.error(`Server error: ${err.message}`)
    process.exit(1)
  })

  process.on('SIGINT', () => {
    server.close()
    if (os.platform() !== 'win32') {
      try {
        if (fs.existsSync(SOCKET_PATH)) {
          fs.unlinkSync(SOCKET_PATH)
          console.log(`Cleaned up socket file: ${SOCKET_PATH}`)
        }
      } catch (err) {
        console.error(`Failed to clean up socket file on exit: ${err.message}`)
      }
    }
    console.log('Log server stopped.')
    process.exit()
  })
}

startLogServer()