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
Display active and inactive memory.
Display disk statistics.
Display the number of forks since the system was booted.
Display the names and sizes of various kernel objects stored in a cache known as the slab layer. Also see the slabtop command.
Don't print new header lines when the screen is full.
Display detailed statistics for the specified partition.
Display various even counters and memory statistics.
Switch the output units. Possible values are k, K, m or M.
Print version number, then exit.
VM mode fields
r Processes waiting for runtime.
b Uninterruptible sleeping processes.
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.
si Memory swapped in from disk each second, in kilobytes.
so Memory swapped out to disk each second, in kilobytes.
bi Blocks sent to block devices each second.
bo Blocks received from block devices each second.
in Interrupts per second, including clock interrupts.
cs Context switches per second.
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
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.
cur I/O in progress
s Seconds spent doing I/O.
Disk partition mode fields
Total reads issued to this partition.
Total sectors read for this partition.
Total writes issued to this partition.
Total write requests for this partition.
Slab mode fields
Cache name.
Number of currently active objects.
Total number of available objects.
Size of each object.
Number of pages with at least one active object.
Total number of allocated pages.
Number of pages per slab.
