clockadd

## Name

clockadd — adjust the local UNIX clock, once

## Synopsis

`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.

### Note

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.