1FREE(1)                          User Commands                         FREE(1)
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NAME

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

9       free [options]
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DESCRIPTION

12       free  displays the total amount of free and used physical and swap mem‐
13       ory in the system, as well as the buffers and caches used by  the  ker‐
14       nel.  The  information  is  gathered by parsing /proc/meminfo. The dis‐
15       played columns are:
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17       total  Total installed memory (MemTotal and SwapTotal in /proc/meminfo)
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19       used   Used memory (calculated as total - free - buffers - cache)
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21       free   Unused memory (MemFree and SwapFree in /proc/meminfo)
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23       shared Memory used (mostly) by tmpfs (Shmem in /proc/meminfo)
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25       buffers
26              Memory used by kernel buffers (Buffers in /proc/meminfo)
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28       cache  Memory used by the page cache and slabs (Cached and SReclaimable
29              in /proc/meminfo)
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31       buff/cache
32              Sum of buffers and cache
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34       available
35              Estimation  of  how  much  memory  is available for starting new
36              applications, without swapping. Unlike the data provided by  the
37              cache  or  free fields, this field takes into account page cache
38              and also that not all reclaimable memory slabs will be reclaimed
39              due to items being in use (MemAvailable in /proc/meminfo, avail‐
40              able on kernels 3.14, emulated on kernels 2.6.27+, otherwise the
41              same as free)
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OPTIONS

44       -b, --bytes
45              Display the amount of memory in bytes.
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47       -k, --kibi
48              Display the amount of memory in kibibytes.  This is the default.
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50       -m, --mebi
51              Display the amount of memory in mebibytes.
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53       -g, --gibi
54              Display the amount of memory in gibibytes.
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56       --tebi Display the amount of memory in tebibytes.
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58       --pebi Display the amount of memory in pebibytes.
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60       --kilo Display the amount of memory in kilobytes. Implies --si.
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62       --mega Display the amount of memory in megabytes. Implies --si.
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64       --giga Display the amount of memory in gigabytes. Implies --si.
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66       --tera Display the amount of memory in terabytes. Implies --si.
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68       --peta Display the amount of memory in petabytes. Implies --si.
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70       -h, --human
71              Show  all  output  fields automatically scaled to shortest three
72              digit unit and display the units of print out.  Following  units
73              are used.
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75                B = bytes
76                Ki = kibibyte
77                Mi = mebibyte
78                Gi = gibibyte
79                Ti = tebibyte
80                Pi = pebibyte
81
82              If  unit  is  missing, and you have exbibyte of RAM or swap, the
83              number is in tebibytes and columns might  not  be  aligned  with
84              header.
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86       -w, --wide
87              Switch  to  the  wide  mode. The wide mode produces lines longer
88              than 80 characters. In this mode buffers and cache are  reported
89              in two separate columns.
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91       -c, --count count
92              Display the result count times.  Requires the -s option.
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94       -l, --lohi
95              Show detailed low and high memory statistics.
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97       -s, --seconds delay
98              Continuously  display  the result delay  seconds apart.  You may
99              actually specify any  floating  point  number  for  delay  using
100              either  .  or  ,  for  decimal  point.   usleep(3)  is  used for
101              microsecond resolution delay times.
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103       --si   Use kilo, mega, giga etc (power of 1000) instead of kibi,  mebi,
104              gibi (power of 1024).
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106       -t, --total
107              Display a line showing the column totals.
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109       --help Print help.
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111       -V, --version
112              Display version information.
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FILES

115       /proc/meminfo
116              memory information
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BUGS

119       The  value  for  the shared column is not available from kernels before
120       2.6.32 and is displayed as zero.
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122       Please send bug reports to
123              ⟨procps@freelists.org⟩
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SEE ALSO

126       ps(1), slabtop(1), top(1), vmstat(8).
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130procps-ng                         2018-05-31                           FREE(1)