ntp-cli

A tiny CLI tool to call NTP servers.

Features

• ⏰ Get the current time from NTP servers.
• 📝 Supports multiple time formats.
• 🤫 Quiet mode to suppress output.

Install

• Build it yourself: run go build -o ntp-cli
• Download from GitHub Releases
  If you are on macOS or Linux, don't forget to give execute permission: chmod +x ntp-cli
  Also, for macOS, run xattr -c ntp-cli to remove the quarantine attribute.

Usage

./ntp-cli [flags]

Examples

Please note that --address conflicts with --hostname and --port.

# Call default NTP server
$ ./ntp-cli
Calling NTP server at pool.ntp.org:123...
Current time: Tue Apr  1 23:50:00 JST 2025

# Call NTP server with hostname and default port
$ ./ntp-cli -h time.apple.com
Calling NTP server at time.apple.com:123...
Current time: Tue Apr  1 23:50:59 JST 2025

# Silence the output
$ ./ntp-cli -a time.apple.com:123 -q
$ ./ntp-cli -h time.apple.com -p 123 -q
Tue Apr  1 23:53:09 JST 2025

# Change the time format
$ ./ntp-cli -f RFC3339 -q
2025-04-01T23:57:00+09:00

# This causes an error because you can't specify both address and hostname
$ ./ntp-cli -h time.apple.com -a pool.ntp.org:123
invalid arguments: you can either specify an address or a hostname, but not both

# Call NTP servers in parallel
$ ./ntp-cli -h time.apple.com -p 123 --parallel time.apple.com:234,pool.ntp.org:123
Calling NTP server at pool.ntp.org:123...
Calling NTP server at time.apple.com:234... # This fails
Calling NTP server at time.apple.com:123...
Current time: Fri Apr  4 00:45:38 JST 2025

# Call NTP server with fallback
$ ./ntp-cli -h time.apple.com -p 234 --fallback time.apple.com:123,time.apple.com:245
Calling NTP server at time.apple.com:234...
Reading the response failed:  read udp 192.168.2.107:62348->17.253.68.253:234: i/o timeout
Calling NTP server at time.apple.com:123...
Current time: Fri Apr  4 00:33:26 JST 2025

Flags

• -h, --help: Show help message.

• -a <string>, --address <string>:
  The address of the NTP server. (default: pool.ntp.org:123)

• -h <string>, --hostname <string>:
  The hostname of the NTP server. (default: pool.ntp.org)

• -p <int>, --port <int>:
  The port of the NTP server. (default: 123)

• -f <string>, --format <string>:
  The format of the time. (default: RFC3339)

  Available formats:

  Format	Example
  Layout	01/02 03:04:05PM '06 -0700
  ANSIC	Mon Jan _2 15:04:05 2006
  UnixDate	Mon Jan _2 15:04:05 MST 2006
  RubyDate	Mon Jan 02 15:04:05 -0700 2006
  RFC822	02 Jan 06 15:04 MST
  RFC822Z	02 Jan 06 15:04 -0700
  RFC850	Monday, 02-Jan-06 15:04:05 MST
  RFC1123	Mon, 02 Jan 2006 15:04:05 MST
  RFC1123Z	Mon, 02 Jan 2006 15:04:05 -0700
  RFC3339	2006-01-02T15:04:05Z07:00
  RFC3339Nano	2006-01-02T15:04:05.999999999Z07:00
  Kitchen	3:04PM
  Stamp	Jan _2 15:04:05
  StampMilli	Jan _2 15:04:05.000
  StampMicro	Jan _2 15:04:05.000000
  StampNano	Jan _2 15:04:05.000000000
  DateTime	2006-01-02 15:04:05
  DateOnly	2006-01-02
  TimeOnly	15:04:05
  Seconds1900	3952507337
  Seconds1970	1743518576

• -q, --quiet: Suppress output. Only the time and errors will be printed.

• --fallback <string>: Fallback server addresses to call if the primary server fails. Separated by commas.

• --parallel <string>: Server addresses to call in parallel. Separated by commas.