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.\"	@(#)iostat.8	6.8 (Berkeley) 4/24/91
.\"
.TH IOSTAT 8 "April 24, 1991"
.UC 4
.SH NAME
iostat \- report I/O statistics
.SH SYNOPSIS
.nf
.ft B
iostat [ \-c count ] [ \-M core ] [ \-N system ]
.ti +5
[ \-w wait ] [ drives ]
.ft R
.fi
.SH DESCRIPTION
.I Iostat
reports certain kernel statistics kept about terminal, disk and cpu
activity.
.PP
The options are as follows:
.TP
\-c
Repeat the display
.I 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
.I wait
interval is specified, the default is 1 second.
.TP
\-M
Extract values associated with the name list from the specified core
instead of the default ``/dev/kmem''.
.TP
\-N
Extract the name list from the specified system instead of the default
``/386bsd''.
.TP
\-w
Pause
.I wait
seconds between each display.
If no repeat
.I count
is specified, the default is infinity.
.PP
.I Iostat
displays its information in the following format:
.TP
tty
.nf
.RS
tin	characters read from terminals
tout	characters written to terminals
.RE
.fi
.TP
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,
.I iostat
displays only the first four drives.
To force
.I iostat
to display specific drives, their names may be supplied on the command
line.
.sp
.nf
.RS
sps	sectors transferred per second
tps	transfers per second
msps	milliseconds per average seek (including implied
	seeks and rotational latency)
.RE
.fi
.TP
cpu
.nf
.RS
us	% of cpu time in user mode
ni	% of cpu time in user mode running niced processes
sy	% of cpu time in system mode
id	% of cpu time in idle mode
.RE
.fi
.SH FILES
.ta \w'/dev/kmem  'u
/386bsd	default kernel namelist
.br
/dev/kmem	default memory file
.SH SEE ALSO
.IR fstat (1),
.IR netstat (1),
.IR nfsstat (1),
.IR ps (1),
.IR systat (1),
.IR vmstat (1),
.IR pstat (8)
.sp
The sections starting with ``Interpreting system activity'' in
.IR "Installing and Operating 4.3BSD" .