procps/free.1

.\"             -*-Nroff-*-
.\"  This page Copyright (C) 1993 Matt Welsh, mdw@sunsite.unc.edu.
.\"  Long options where added at April 15th, 2011.
.\"  Freely distributable under the terms of the GPL
.TH FREE 1 "September 2011" "procps-ng" "User Commands"
.SH NAME
free \- Display amount of free and used memory in the system
.SH SYNOPSIS
.B free
.RI [ options ]
.SH DESCRIPTION
.B free
displays the total amount of free and used physical and swap memory in the
system, as well as the buffers and caches used by the kernel. The
information is gathered by parsing /proc/meminfo. The displayed
columns are:
.TP
\fBtotal\fR
Total installed memory (MemTotal and SwapTotal in /proc/meminfo)
.TP
\fBused\fR
Used memory (calculated as total - free)
.TP
\fBfree\fR
Unused memory (MemFree and SwapFree in /proc/meminfo)
.TP
\fBshared\fR
Memory used (mostly) by tmpfs (Shmem in /proc/meminfo, available on
kernels 2.6.32, displayed as zero if not available)
.TP
\fBbuffers\fR
Memory used by kernel buffers (Buffers in /proc/meminfo)
.TP
\fBcached\fR
Memory used by the page cache (Cached in /proc/meminfo)
.TP
\fBavailable\fR
Estimation of how much memory is available for starting
new applications, without swapping. Unlike the data
provided by the \fBcached\fR or \fBfree\fR 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+, displayed as zero if not available)
.SH OPTIONS
.TP
\fB\-b\fR, \fB\-\-bytes\fR
Display the amount of memory in bytes.
.TP
\fB\-k\fR, \fB\-\-kilo\fR
Display the amount of memory in kilobytes.  This is the default.
.TP
\fB\-m\fR, \fB\-\-mega\fR
Display the amount of memory in megabytes.
.TP
\fB\-g\fR, \fB\-\-giga\fR
Display the amount of memory in gigabytes.
.TP
\fB\-\-tera\fR
Display the amount of memory in terabytes.
.TP
\fB\-h\fR, \fB\-\-human\fP
Show all output fields automatically scaled to shortest three digit unit and
display the units of print out.  Following units are used.
.sp
.nf
  B = bytes
  K = kilos
  M = megas
  G = gigas
  T = teras
.fi
.sp
If unit is missing, and you have petabyte of RAM or swap, the number is in
terabytes and columns might not be aligned with header.
.TP
\fB\-a\fR, \fB\-\-available\fR
Display the estimation of memory available for starting new applications,
without swapping. This switch makes the output wider than 80 characters.
.TP
\fB\-c\fR, \fB\-\-count\fR \fIcount\fR
Display the result
.I count
times.  Requires the
.B \-s
option.
.TP
\fB\-l\fR, \fB\-\-lohi\fR
Show detailed low and high memory statistics.
.TP
\fB\-o\fR, \fB\-\-old\fR
Display the output in old format, the only difference being this option
will disable the display of the "buffer adjusted" line.
.TP
\fB\-s\fR, \fB\-\-seconds\fR \fIseconds\fR
Continuously display the result delay
.I seconds
apart.  You may actually specify any floating point number for
.IR delay ,
.BR usleep (3)
is used for microsecond resolution delay times.
.TP
\fB\-\-si\fR
Use power of 1000 not 1024.
.TP
\fB\-t\fR, \fB\-\-total\fR
Display a line showing the column totals.
.TP
\fB\-\-help\fR
Print help.
.TP
\fB\-V\fR, \fB\-\-version\fR
Display version information.
.PD
.SH FILES
.TP
/proc/meminfo
memory information
.PD
.SH "SEE ALSO"
.BR ps (1),
.BR slabtop (1),
.BR top "(1),
.BR vmstat (8).
.SH AUTHORS
Written by Brian Edmonds.
.SH "REPORTING BUGS"
Please send bug reports to
.UR procps@freelists.org
.UE