.\" Copyright (c) 1985, 1991, 1993 .\" The Regents of the University of California. All rights reserved. .\" .\" Redistribution and use in source and binary forms, with or without .\" modification, are permitted provided that the following conditions .\" are met: .\" 1. Redistributions of source code must retain the above copyright .\" notice, this list of conditions and the following disclaimer. .\" 2. Redistributions in binary form must reproduce the above copyright .\" notice, this list of conditions and the following disclaimer in the .\" documentation and/or other materials provided with the distribution. .\" 3. All advertising materials mentioning features or use of this software .\" must display the following acknowledgement: .\" This product includes software developed by the University of .\" California, Berkeley and its contributors. .\" 4. Neither the name of the University nor the names of its contributors .\" may be used to endorse or promote products derived from this software .\" without specific prior written permission. .\" .\" THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND .\" ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE .\" IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE .\" ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE .\" FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL .\" DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS .\" OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) .\" HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT .\" LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY .\" OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF .\" SUCH DAMAGE. .\" .\" @(#)iostat.8 8.1 (Berkeley) 6/6/93 .\" .Dd June 6, 1993 .Dt IOSTAT 8 .Os BSD 4 .Sh NAME .Nm iostat .Nd report .Tn I/O statistics .Sh SYNOPSIS .Nm iostat .Op Fl c Ar count .Op Fl M Ar core .Op Fl N Ar system .Op Fl w Ar wait .Op Ar drives .Sh DESCRIPTION .Nm Iostat displays kernel .Tn I/O statistics on terminal, disk and cpu operations. .Pp The options are as follows: .Bl -tag -width flag .It Fl c Repeat the display .Ar count times. The first display is for the time since a reboot and each subsequent report is for the time period since the last display. If no .Ar wait interval is specified, the default is 1 second. .It Fl M Extract values associated with the name list from the specified core instead of the default .Dq Pa /dev/kmem . .It Fl N Extract the name list from the specified system instead of the default .Dq Pa /vmunix . .It Fl w Pause .Ar wait seconds between each display. If no repeat .Ar count is specified, the default is infinity. .El .Pp .Nm Iostat displays its information in the following format: .Bl -tag -width flag .It tty .Bl -tag -width indent -compact .It tin characters read from terminals .It tout characters written to terminals .El .It disks Disk operations (this field is system dependent). The header of the field is the disk name and unit number. If more than four disk drives are configured in the system, .Nm iostat displays only the first four drives. To force .Nm iostat to display specific drives, their names may be supplied on the command line. .Pp .Bl -tag -width indent -compact .It sps sectors transferred per second .It tps transfers per second .It msps milliseconds per average seek (including implied seeks and rotational latency) .El .It cpu .Bl -tag -width indent -compact .It \&us % of cpu time in user mode .It \&ni % of cpu time in user mode running niced processes .It \&sy % of cpu time in system mode .It \&id % of cpu time in idle mode .El .El .Sh FILES .Bl -tag -width /dev/kmem -compact .It Pa /vmunix Default kernel namelist. .It Pa /dev/kmem Default memory file. .El .Sh SEE ALSO .Xr fstat 1 , .Xr netstat 1 , .Xr nfsstat 1 , .Xr \&ps 1 , .Xr systat 1 , .Xr vmstat 1 , .Xr pstat 8 .Pp The sections starting with ``Interpreting system activity'' in .%T "Installing and Operating 4.3BSD" .