Linux Command Directory


Linux in a Nutshell

This directory of Linux commands is from Linux in a Nutshell, 5th Edition.

Click on any of the 687 commands below to get a description and list of available options. All links in the command summaries point to the online version of the book on Safari Bookshelf.

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vmstat

vmstat [options] [interval [count] ]

System administration command. Print report on virtual memory statistics, including information on processes, memory, paging block I/O, traps, system and CPU usage. vmstat initially reports average values since the last system reboot. If given a sampling period interval in seconds, it prints additional statistics for each interval. If specified, vmstat exits when it has completed count reports. Otherwise, it continues until it receives a Ctrl-C, printing a new header line each time it fills the screen.

Options

-a

Display active and inactive memory.

-d

Display disk statistics.

-f

Display the number of forks since the system was booted.

-m

Display the names and sizes of various kernel objects stored in a cache known as the slab layer. Also see the slabtop command.

-n

Don't print new header lines when the screen is full.

-p partition

Display detailed statistics for the specified partition.

-s

Display various even counters and memory statistics.

-S units

Switch the output units. Possible values are k, K, m or M.

-V

Print version number, then exit.

VM mode fields

procs
r

Processes waiting for runtime.

b

Uninterruptible sleeping processes.

memory
swpd

Virtual memory used, in kilobytes.

free

Idle memory, in kilobytes.

buff

Memory used as buffers, in kilobytes.

cache

Cache memory, in kilobytes.

inactive

Inactive memory, in kilobytes, displayed with -a.

active

Active memory, in kilobytes; displayed with -a.

swap
si

Memory swapped in from disk each second, in kilobytes.

so

Memory swapped out to disk each second, in kilobytes.

io
bi

Blocks sent to block devices each second.

bo

Blocks received from block devices each second.

system
in

Interrupts per second, including clock interrupts.

cs

Context switches per second.

cpu
us

Percentage of CPU time consumed by user processes.

sy

Percentage of CPU time consumed by system processes.

id

Percentage of CPU time spent idle.

wa

Percentage of CPU time spent waiting for I/O.

Disk mode fields

Reads and Writes
total

Total reads or writes completed successfully.

merged

Reads or writes grouped into one I/O.

sectors

Sectors read or written successfully.

ms

Milliseconds spent reading or writing.

IO
cur

I/O in progress

s

Seconds spent doing I/O.

Disk partition mode fields

reads

Total reads issued to this partition.

read sectors

Total sectors read for this partition.

writes

Total writes issued to this partition.

requested writes

Total write requests for this partition.

Slab mode fields

cache

Cache name.

num

Number of currently active objects.

total

Total number of available objects.

size

Size of each object.

pages

Number of pages with at least one active object.

totpages

Total number of allocated pages.

pslab

Number of pages per slab.


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