Report Central Processing Unit (CPU) statistics and i/o statistics for devices, partitions and network filesystems (NFS).
Syntax iostat [-CUdKIoT?] [-c count] [-n devs] [-w wait] [drives] Options -C Display CPU statistics. This is on by default, unless -d is specified. -c Repeat the display count times. If no wait interval is specified, the default is 1 second. -d Display only device statistics. If this flag is turned on, only device statistics will be displayed, unless -C or -U or -T is also specfied to enable the display of CPU, load average or TTY statis- tics. -I Display total statstics for a given time period, rather than aver- age statistics for each second during that time period. -K In the blocks transferred display (-o), display block count in kilobytes rather then the device native block size. -n Display up to devs number of devices. iostat will display fewer devices if there aren't devs devices present. -o Display old-style iostat device statistics. Sectors per second, transfers per second, and miliseconds per seek are displayed. If -I is specified, total blocks/sectors, total transfers, and miliseconds per seek are displayed. -T Display TTY statistics. This is on by default, unless -d is speci- fied. -U Display system load averages. This is on by default, unless -d is specified. -w Pause wait seconds between each display. If no repeat count is specified, the default is infinity. -? Display a usage statement and exit. Iostat displays its information in the following format: tty tin characters read from terminals tout characters written to terminals devices Device operations. The header of the field is the device name and unit number. iostat will display as many devices as will fit in a standard 80 column screen, or the maximum number of devices in the system, whichever is smaller. If -n is specified on the command line, iostat will display the smaller of the requested number of devices, and the maximum number of devices in the system. To force iostat to display specific drives, their names may be supplied on the command line. iostat will not display more devices than will fit in an 80 column screen, unless the -n argument is given on the command line to specify a maximum number of devices to display, or the list of specified devices exceeds 80 columns. If fewer devices are specified on the command line than will fit in an 80 column screen, iostat will show only the specified devices. The standard iostat device display shows the following statistics: KB/t kilobytes per transfer tps transfers per second MB/s megabytes per second The standard iostat device display, with the -I flag specified, shows the following statistics: KB/t kilobytes per transfer xfrs total number of transfers MB total number of megabytes transferred The old-style iostat display (using -o) shows the following statis- tics: sps sectors transferred per second tps transfers per second msps average milliseconds per transaction The old-style iostat display, with the -I flag specified, shows the following statistics: blk total blocks/sectors transferred xfr total transfers msps average milliseconds per transaction cpu us % of cpu time in user mode sy % of cpu time in system mode id % of cpu time in idle mode
Display statistics for the first and third disk devices device every sec- ond ad infinitum:
$ iostat -w 1 disk0 disk2
Display the statistics for the first four devices in the system twice, with a one second display interval:
$ iostat -c 2
Display total statistics every three seconds ad infinitum:
$ iostat -Iw 3
“Celebrity is a mask that eats into the face. As soon as one is aware of being somebody, to be watched and listened to with extra interest, input ceases, and the performer goes blind and deaf in his over animation. One can either see or be seen” ~ John Updike
Related macOS commands:
fstat(1), netstat(1), pstat(8)
ps - Process status.
top - List processes running on the system.