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from: @(#)iostat.8 8.1 (Berkeley) 6/6/93
.Dd August 25, 1998 .Dt IOSTAT 8 .Os NetBSD 1.1 .Sh NAME .Nm iostat .Nd report .Tn I/O statistics .Sh SYNOPSIS .Nm .Op Fl CdDITx .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 displays kernel .Tn I/O statistics on terminal, disk and cpu operations. By default, .Nm displays one line of statistics averaged over the machine's run time. The use of .Fl c presents successive lines averaged over the .Ar wait period. The .Fl I option causes .Nm to print raw, unaveraged values.
p Only the last disk option specified .Fl ( d , .Fl D , or .Fl x ) is used.
p The options are as follows: l -tag -width flag t Fl c Repeat the display .Ar count times. Unless the .Fl I flag is in effect, 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. t Fl C Show cpu statistics. This is enabled by default unless the .Fl d , .Fl D , .Fl T , or .Fl x flags are used. t Fl d Show disk statistics. This is the default. Displays kilobytes per transfer, number of transfers, and megabytes transferred. Use of this flag disables display of cpu and tty statistics. t Fl D Show alternative disk statistics. Displays kilobytes transferred, number of transfers, and time spent in transfers. Use of this flag disables the default display. t Fl I Show the running total values, rather than an average. t Fl M Extract values associated with the name list from the specified core instead of the default .Dq Pa /dev/mem . t Fl N Extract the name list from the specified system instead of the default .Dq Pa /netbsd . t Fl T Show tty statistics. This is enabled by default unless the .Fl C , .Fl d , or .Fl D flags are used. t Fl w Pause .Ar wait seconds between each display. If no repeat .Ar count is specified, the default is infinity. t Fl x Show extended disk statisics. Each disk is displayed on a line of its own with all available statistics. This option overrides all other display options, and all disks are displayed regardless of whether specific disks are provided as arguments. .El
p .Nm displays its information in the following format: l -tag -width flag t tty l -tag -width indent -compact t tin characters read from terminals t tout characters written to terminals .El t disks Disk operations. The header of the field is the disk name and unit number. If more than four disk drives are configured in the system, .Nm displays only the first four drives. To force .Nm to display specific drives, their names may be supplied on the command line.
p l -tag -width indent -compact t KB/t Kilobytes transferred per disk transfer t t/s transfers per second t MB/s Megabytes transferred per second
p .El The alternative display format, (selected with .Fl D ) , presents the following values. l -tag -width indent -compact t KB Kilobytes transferred t xfr Disk transfers t time Seconds spent in disk activity .El t cpu l -tag -width indent -compact t us % of cpu time in user mode t ni % of cpu time in user mode running niced processes t sy % of cpu time in system mode t id % of cpu time in idle mode .El .El .Sh FILES l -tag -width /dev/mem -compact t Pa /netbsd Default kernel namelist. t Pa /dev/mem Default memory file. .El .Sh SEE ALSO .Xr fstat 1 , .Xr netstat 1 , .Xr nfsstat 1 , .Xr ps 1 , .Xr systat 1 , .Xr pstat 8 , .Xr vmstat 8
p The sections starting with ``Interpreting system activity'' in .%T "Installing and Operating 4.3BSD" . .Sh HISTORY .Nm appeared in .At v6 . The .Fl x option was added in .Nx 1.4 .
Indexes created Sun Oct 19 18:09:56 GMT 2025