ntpcl

A simple time client to fetch and optionally set system time from NTP, HTTP, Daytime, or Time Protocol sources.

Install

go install github.com/earentir/ntpcl@latest

Or build from source:

git clone https://github.com/earentir/ntpcl.git
cd ntpcl
go build -o ntpcl .

Usage

Default (NTP pool)

./ntpcl

Queries europe.pool.ntp.org and prints a table with server time, local time, offset, RTT, and NTP details.

Set system time from NTP

sudo ./ntpcl --set
./ntpcl ntp pool.ntp.org --set
./ntpcl --set ntp pool.ntp.org

Persistent flags work before or after the subcommand.

High accuracy mode

./ntpcl ntp pool.ntp.org --high-accuracy
sudo ./ntpcl ntp pool.ntp.org --high-accuracy --set

Collects multiple spaced NTP samples, drops outliers, and uses the median offset.

Other sources

./ntpcl http https://example.com
./ntpcl daytime time.nist.gov
./ntpcl time time.nist.gov
./ntpcl windows-time dc.example.com

windows-time queries a Windows Time host over unsigned NTP. It is not MS-SNTP authenticated.

Safety flags

./ntpcl --dry-run --set ntp pool.ntp.org
./ntpcl --max-delta 5s --set ntp pool.ntp.org
./ntpcl --force --set http https://example.com

• --dry-run shows what would be set without changing the clock
• --max-delta refuses large clock steps (default 1s; 100ms in high-accuracy mode)
• --force overrides max-delta and high-RTT checks for coarse sources

Output formats

./ntpcl --format json ntp pool.ntp.org
./ntpcl --format unix ntp pool.ntp.org
./ntpcl --format rfc3339 --quiet ntp pool.ntp.org
./ntpcl --no-color ntp pool.ntp.org

Set via system commands

sudo ./ntpcl --set --system-tools ntp pool.ntp.org

Uses date on Linux/macOS or PowerShell Set-Date on Windows instead of direct syscalls.

Exit codes

Code	Meaning
0	Success
1	General error
2	Usage error
3	Network error
4	Invalid time / refused clock step
5	Permission denied

License

MIT — see LICENSE.