free 

```
[linuxstudy@xxxx ~]$ free
              total        used        free      shared  buff/cache   available
Mem:        2895012     1661628      207992       74916     1025392      981648
Swap:       1572860       18268     1554592
[linuxstudy@xxxx ~]$ free -t
              total        used        free      shared  buff/cache   available
Mem:        2895012     1661056      208544       74916     1025412      982220
Swap:       1572860       18268     1554592
Total:      4467872     1679324     1763136
```
```
FREE(1)                                            User Commands                                           FREE(1)



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

SYNOPSIS
       free [options]

DESCRIPTION
       free displays the total amount of free and used physical and swap memory in the system, as well as the buf‐
       fers and caches used by the kernel. The information is gathered by  parsing  /proc/meminfo.  The  displayed
       columns are:

       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, available on kernels 2.6.32, displayed as
              zero if not available)

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

       -k, --kilo
              Display the amount of memory in kilobytes.  This is the default.

       -m, --mega
              Display the amount of memory in megabytes.

       -g, --giga
              Display the amount of memory in gigabytes.

       --tera Display the amount of memory in terabytes.

       --peta Display the amount of memory in petabytes.

       -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
                K = kilos
                M = megas
                G = gigas
                T = teras
                P = petas

              If unit is missing, and you have exabyte of RAM or swap, the number  is  in  terabytes  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 buf‐
              fers 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 seconds
              Continuously display the result delay seconds apart.  You may actually specify  any  floating  point
              number for delay, usleep(3) is used for microsecond resolution delay times.

       --si   Use power of 1000 not 1024.

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

       --help Print help.

       -V, --version
              Display version information.

FILES
       /proc/meminfo
              memory information

SEE ALSO
       ps(1), slabtop(1), top(1), vmstat(8).

AUTHORS
       Written by Brian Edmonds.

REPORTING BUGS
       Please send bug reports to ⟨procps@freelists.org⟩



procps-ng                                            July 2014                                             FREE(1)
```