iostat(1)iostat(1)Nameiostat - report I/O statistics
Syntaxiostat [ -c ] [ -t ] [ disknames ] [ interval ] [ count ]
The command reports I/O statistics for terminals, disks and cpus. For
terminals the number of input and output characters are counted. For
disks the number of 512 byte blocks per second and number of transfers
per second are displayed. For cpus, it provides the percentage of time
the system has spent in user mode, in user mode running low priority
(niced) processes, in system mode, and idling. On multiprocessor sys‐
tems these cpu statistics represent a cumulative summary of all the
The optional disknames argument causes disk statistics to be displayed
for the specified disks. If this argument is not specified then disk
statistics will be displayed for the first 3 disks only.
The optional interval argument causes to report once each interval sec‐
onds. The first report is for all time since a reboot and each subse‐
quent report is for the last interval only.
The optional count argument restricts the number of reports.
Options-c Displays the percentage of time each cpu spent in user mode, run‐
ning low priority (nice'd) processes, in system mode, and idling.
-t Displays the number of characters read from and written to termi‐
This example will cause cpu and disk statistics for the 5 disks ra0,
ra1, ra2, ra3, and ra4.
iostat ra0 ra1 ra2 ra3 ra4
This example will cause cpu, terminal, and disk statistics for ra0 to
be displayed and updated every 2 seconds.
iostat-t ra0 2
FilesSee Alsovmstat(1), cpustat(1)iostat(1)