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Linux commands
This thread is just to give reference to a couple cammands that may help someone. I wanting to find out how much total memory my system has, and was being listed by linux, so I went through my linux books and couldn't find any command that gave me the info I needed. So I did some searching on the net and found two commands that list memory. Most of you may already know them, but for those that don't here they are and the man page.
Code:
vmstat
VMSTAT(8) Linux Administrator’s Manual VMSTAT(8)
NAME
vmstat - Report virtual memory statistics
SYNOPSIS
vmstat [-a] [-n] [delay [ count]]
vmstat [-f] [-s] [-m]
vmstat [-S unit]
vmstat [-d]
vmstat [-p disk partition]
vmstat [-V]
DESCRIPTION
vmstat reports information about processes, memory, paging, block IO,
traps, and cpu activity.
The first report produced gives averages since the last reboot. Addi-
tional reports give information on a sampling period of length delay.
The process and memory reports are instantaneous in either case.
Options
The -a switch displays active/inactive memory, given a 2.5.41 kernel or
better.
The -f switch displays the number of forks since boot. This includes
the fork, vfork, and clone system calls, and is equivalent to the total
number of tasks created. Each process is represented by one or more
tasks, depending on thread usage. This display does not repeat.
The -m displays slabinfo.
The -n switch causes the header to be displayed only once rather than
periodically.
The -s switch displays a table of various event counters and memory
statistics. This display does not repeat.
delay is the delay between updates in seconds. If no delay is speci-
fied, only one report is printed with the average values since boot.
count is the number of updates. If no count is specified and delay is
defined, count defaults to infinity.
The -d reports disk statistics (2.5.70 or above required)
The -p followed by some partition name for detailed statistics (2.5.70
or above required)
The -S followed by k or K or m or M switches outputs between 1000,
1024, 1000000, or 1048576 bytes
The -V switch results in displaying version information.
FIELD DESCRIPTION FOR VM MODE
Procs
r: The number of processes waiting for run time.
b: The number of processes in uninterruptible sleep.
Memory
swpd: the amount of virtual memory used.
free: the amount of idle memory.
buff: the amount of memory used as buffers.
cache: the amount of memory used as cache.
inact: the amount of inactive memory. (-a option)
active: the amount of active memory. (-a option)
Swap
si: Amount of memory swapped in from disk (/s).
so: Amount of memory swapped to disk (/s).
IO
bi: Blocks received from a block device (blocks/s).
bo: Blocks sent to a block device (blocks/s).
System
in: The number of interrupts per second, including the clock.
cs: The number of context switches per second.
CPU
These are percentages of total CPU time.
us: Time spent running non-kernel code. (user time, including nice time)
sy: Time spent running kernel code. (system time)
id: Time spent idle. Prior to Linux 2.5.41, this includes IO-wait time.
wa: Time spent waiting for IO. Prior to Linux 2.5.41, shown as zero.
FIELD DESCRIPTION FOR DISK MODE
Reads
total: Total reads completed successfully
merged: grouped reads (resulting in one I/O)
sectors: Sectors read successfully
ms: milliseconds spent reading
Writes
total: Total writes completed successfully
merged: grouped writes (resulting in one I/O)
sectors: Sectors written successfully
ms: milliseconds spent writing
IO
cur: I/O in progress
s: seconds spent for I/O
FIELD DESCRIPTION FOR DISK PARTITION MODE
reads: Total number of reads issued to this partition
read sectors: Total read sectors for partition
writes : Total number of writes issued to this partition
requested writes: Total number of write requests made for partition
FIELD DESCRIPTION FOR SLAB MODE
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
NOTES
vmstat does not require special permissions.
These reports are intended to help identify system bottlenecks. Linux
vmstat does not count itself as a running process.
All linux blocks are currently 1024 bytes. Old kernels may report
blocks as 512 bytes, 2048 bytes, or 4096 bytes.
Since procps 3.1.9, vmstat lets you choose units (k, K, m, M) default
is K (1024 bytes) in the default mode
vmstat uses slabinfo 1.1 FIXME
FILES
/proc/meminfo
/proc/stat
/proc/*/stat
and
Code:
free - display information about free and used memory on the system
SYNOPSIS
free [-b|-k|-m|-g] [-l] [-o] [-t] [-s delay ] [-c count ]
DESCRIPTION
free(1) displays the total amount of free and used physical memory and swap space in the system, as well as the buffers and cache consumed by the kernel.
OPTIONS
Normal invocation of free(1) does not require any options. The output, however, can be fine-tuned by specifying one or more of the following flags:
-b, --bytes
Display output in bytes.
-k, --kb
Display output in kilobytes (KB). This is the default.
-m, --mb
Display output in megabytes (MB).
-g, --gb
Display output in gigabytes (GB).
-l, --lowhigh
Display detailed information about low vs. high memory usage.
-o, --old
Use old format. Specifically, do not display -/+ buffers/cache.
-t, --total
Display total summary for physical memory + swap space.
-c n, --count=n
Display statistics n times, then exit. Used in conjunction with the -s flag. Default is to display only once, unless -s was specified, in which case default is to repeat until interrupted.
-s n, --repeat=n
Repeat, pausing every n seconds in-between.
-V, --version
Display version information and exit.
--help
Display usage information and exit
top
is also a command that shows mem. but it didn't show it the way I needed.
Hope this helps someone,
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Sorry don't know what's up with the double thread?????
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I use the free -m command a lot.
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