clockadd 1 user commands djbwares
clockadd adjust the local UNIX clock, once
`clockadd`

## Description

`clockadd` reads a TAI64NA time adjustment from standard input, as generated by a program such as taiclock 1 or sntpclock 1. It then adds that adjustment to the local UNIX clock.

`clockadd` must be run by the superuser.

The adjustment must be a single 16-byte packet, readable in a single call to read 2. `clockadd` does not require that its standard input be a stream in blocking I/O mode.

The time is always "stepped" by calling settimeofday 2. `clockadd` does not call adjtime 2.

## History

`clockadd` was originally part of Daniel J. Bernstein's clockspeed toolset in 1998.

## Author

Original code and documentation by Daniel J. Bernstein. Documentation modernizations by Jonathan de Boyne Pollard.