linux查看系统内存使用情况

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free - Display amount of free and used memory in the system

描述：

​ total Total installed memory (MemTotal and SwapTotal in /proc/meminfo)

​ used Used memory (calculated as total - free - buffers - cache)

​ free Unused memory (MemFree and SwapFree in /proc/meminfo)

​ shared Memory used (mostly) by tmpfs (Shmem in /proc/meminfo)

​ buffers Memory used by kernel buffers (Buffers in /proc/meminfo)

​ cache Memory used by the page cache and slabs (Cached and SReclaimable in /proc/meminfo)

​ buff/cache Sum of buffers and cache

​ available
​ Estimation of how much memory is available for starting
​ new applications, without swapping. Unlike the data
​ provided by the cache or free fields, this field takes
​ into account page cache and also that not all reclaimable
​ memory slabs will be reclaimed due to items being in use
​ (MemAvailable in /proc/meminfo, available on kernels 3.14,
​ emulated on kernels 2.6.27+, otherwise the same as free)

OPTIONS

最常用的就是 free -h

直接用free -g的话，不到1G直接舍去。 见下图

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-b, --bytes
              Display the amount of memory in bytes.

       -k, --kibi
              Display the amount of memory in kibibytes.  This is the
              default.

       -m, --mebi
              Display the amount of memory in mebibytes.

       -g, --gibi
              Display the amount of memory in gibibytes.

       --tebi Display the amount of memory in tebibytes.

       --pebi Display the amount of memory in pebibytes.

       --kilo Display the amount of memory in kilobytes. Implies --si.

       --mega Display the amount of memory in megabytes. Implies --si.

       --giga Display the amount of memory in gigabytes. Implies --si.

       --tera Display the amount of memory in terabytes. Implies --si.

       --peta Display the amount of memory in petabytes. Implies --si.

       -h, --human
              Show all output fields automatically scaled to shortest
              three digit unit and display the units of print out.
              Following units are used.

                B = bytes
                Ki = kibibyte
                Mi = mebibyte
                Gi = gibibyte
                Ti = tebibyte
                Pi = pebibyte

              If unit is missing, and you have exbibyte of RAM or swap,
              the number is in tebibytes and columns might not be
              aligned with header.

       -w, --wide
              Switch to the wide mode. The wide mode produces lines
              longer than 80 characters. In this mode buffers and cache
              are reported in two separate columns.

       -c, --count count
              Display the result count times.  Requires the -s option.

       -l, --lohi
              Show detailed low and high memory statistics.

       -s, --seconds delay
              Continuously display the result delay  seconds apart.  You
              may actually specify any floating point number for delay
              using either . or , for decimal point.  usleep(3) is used
              for microsecond resolution delay times.

       --si   Use kilo, mega, giga etc (power of 1000) instead of kibi,
              mebi, gibi (power of 1024).

       -t, --total
              Display a line showing the column totals.

       --help Print help.

       -V, --version
              Display version information.