1*61111Sbostic.\" Copyright (c) 1986, 1991, 1993 2*61111Sbostic.\" The Regents of the University of California. All rights reserved. 325789Smckusick.\" 448352Scael.\" %sccs.include.redist.man% 525789Smckusick.\" 6*61111Sbostic.\" @(#)usleep.3 8.1 (Berkeley) 06/04/93 748352Scael.\" 848352Scael.Dd 948352Scael.Dt USLEEP 3 1048352Scael.Os BSD 4.3 1148352Scael.Sh NAME 1248352Scael.Nm usleep 1348352Scael.Nd suspend execution for interval of microseconds 1448352Scael.Sh SYNOPSIS 1548352Scael.Fd #include <unistd.h> 1648352Scael.Ft void 1748352Scael.Fn usleep "u_int microseconds" 1848352Scael.Sh DESCRIPTION 1948352ScaelThe 2059202Shibler.Fn usleep 2148352Scaelfunction 2248352Scaelsuspends execution of the calling process 2348352Scaelfor 2448352Scael.Fa microseconds 2548352Scaelof time. 2648352ScaelSystem activity or time spent in processing the 2748352Scaelcall may lengthen the sleep slightly. 2848352Scael.Pp 2948352ScaelIf a timer is already running on the process its state is saved. 3048352ScaelIf the value 3148352Scael.Fa microseconds 3248352Scaelis more than or equal to the remaining clock time for the saved timer, 3348352Scaelthe sleep time is set to 3448352Scaelthe remaining clock time. 3548352ScaelThe state of the previous timer 3648352Scaelis restored after 3748352Scael.Fa microseconds 3848352Scaelhas passed. 3948352Scael.Pp 4028215SkarelsThis routine is implemented using 4148352Scael.Xr setitimer 2 ; 4228215Skarelsit requires eight system calls each time it is invoked. 4328215SkarelsA similar but less compatible function can be obtained with a single 4448352Scael.Xr select 2 ; 4548352Scaelsuch a function would not restart after signals, but would not interfere 4628215Skarelswith other uses of 4748352Scael.Xr setitimer . 4848352Scael.Sh SEE ALSO 4948352Scael.Xr setitimer 2 , 5048352Scael.Xr getitimer 2 , 5148352Scael.Xr sigpause 2 , 5248352Scael.Xr ualarm 3 , 5348352Scael.Xr sleep 3 , 5448352Scael.Xr alarm 3 5548352Scael.Sh HISTORY 5648352ScaelThe 5748352Scael.Fn usleep 5848352Scaelfunction appeared in 5948352Scael.Bx 4.3 . 60