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Thread: Linux commands

  1. #1
    Join Date
    Jun 2002
    Location
    Michigan
    Posts
    875

    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,

  2. #2
    Join Date
    Jun 2002
    Location
    Michigan
    Posts
    875
    Sorry don't know what's up with the double thread?????

  3. #3
    Join Date
    Jan 2006
    Location
    UK
    Posts
    121
    I use the free -m command a lot.

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