1FREE(1) User Commands FREE(1)
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6 free - Display amount of free and used memory in the system
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9 free [options]
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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, available
24 on kernels 2.6.32, displayed as zero if not available)
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26 buffers
27 Memory used by kernel buffers (Buffers in /proc/meminfo)
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29 cache Memory used by the page cache and slabs (Cached and Slab in
30 /proc/meminfo)
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32 buff/cache
33 Sum of buffers and cache
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35 available
36 Estimation of how much memory is available for starting new
37 applications, without swapping. Unlike the data provided by the
38 cache or free fields, this field takes into account page cache
39 and also that not all reclaimable memory slabs will be reclaimed
40 due to items being in use (MemAvailable in /proc/meminfo, avail‐
41 able on kernels 3.14, emulated on kernels 2.6.27+, otherwise the
42 same as free)
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45 -b, --bytes
46 Display the amount of memory in bytes.
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48 -k, --kilo
49 Display the amount of memory in kilobytes. This is the default.
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51 -m, --mega
52 Display the amount of memory in megabytes.
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54 -g, --giga
55 Display the amount of memory in gigabytes.
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57 --tera Display the amount of memory in terabytes.
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59 --peta Display the amount of memory in petabytes.
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61 -h, --human
62 Show all output fields automatically scaled to shortest three
63 digit unit and display the units of print out. Following units
64 are used.
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66 B = bytes
67 K = kilos
68 M = megas
69 G = gigas
70 T = teras
71 P = petas
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73 If unit is missing, and you have exabyte of RAM or swap, the
74 number is in terabytes and columns might not be aligned with
75 header.
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77 -w, --wide
78 Switch to the wide mode. The wide mode produces lines longer
79 than 80 characters. In this mode buffers and cache are reported
80 in two separate columns.
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82 -c, --count count
83 Display the result count times. Requires the -s option.
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85 -l, --lohi
86 Show detailed low and high memory statistics.
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88 -s, --seconds seconds
89 Continuously display the result delay seconds apart. You may
90 actually specify any floating point number for delay, usleep(3)
91 is used for microsecond resolution delay times.
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93 --si Use power of 1000 not 1024.
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95 -t, --total
96 Display a line showing the column totals.
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98 --help Print help.
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100 -V, --version
101 Display version information.
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104 /proc/meminfo
105 memory information
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108 ps(1), slabtop(1), top(1), vmstat(8).
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111 Written by Brian Edmonds.
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114 Please send bug reports to ⟨procps@freelists.org⟩
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118procps-ng July 2014 FREE(1)