LSMEM(1) User Commands LSMEM(1)
NAME
lsmem - list the ranges of available memory with their online status
SYNOPSIS
lsmem [options]
DESCRIPTION
The lsmem command lists the ranges of available memory with their online
status. The listed memory blocks correspond to the memory block
representation in sysfs. The command also shows the memory block size
and the amount of memory in online and offline state.
The default output is compatible with original implementation from
s390-tools, but it’s strongly recommended to avoid using default outputs
in your scripts. Always explicitly define expected columns by using the
--output option together with a columns list in environments where a
stable output is required.
The lsmem command lists a new memory range always when the current
memory block distinguish from the previous block by some output column.
This default behavior is possible to override by the --split option
(e.g., lsmem --split=ZONES). The special word "none" may be used to
ignore all differences between memory blocks and to create as large as
possible continuous ranges. The opposite semantic is --all to list
individual memory blocks.
Note that some output columns may provide inaccurate information if a
split policy forces lsmem to ignore differences in some attributes. For
example if you merge removable and non-removable memory blocks to the
one range than all the range will be marked as non-removable on lsmem
output.
Not all columns are supported on all systems. If an unsupported column
is specified, lsmem prints the column but does not provide any data for
it.
Use the --help option to see the columns description.
OPTIONS
-a, --all
List each individual memory block, instead of combining memory
blocks with similar attributes.
-b, --bytes
Print the sizes in bytes rather than in a human-readable format.
By default, the unit, sizes are expressed in, is byte, and unit
prefixes are in power of 2^10 (1024). Abbreviations of symbols are
exhibited truncated in order to reach a better readability, by
exhibiting alone the first letter of them; examples: "1 KiB" and "1
MiB" are respectively exhibited as "1 K" and "1 M", then omitting on
purpose the mention "iB", which is part of these abbreviations.
-J, --json
Use JSON output format.
-n, --noheadings
Do not print a header line.
-o, --output list
Specify which output columns to print. Use --help to get a list of
all supported columns. The default list of columns may be extended
if list is specified in the format +list (e.g., lsmem -o +NODE).
--output-all
Output all available columns.
-P, --pairs
Produce output in the form of key="value" pairs. All potentially
unsafe value characters are hex-escaped (\x<code>).
-r, --raw
Produce output in raw format. All potentially unsafe characters are
hex-escaped (\x<code>).
-S, --split list
Specify which columns (attributes) use to split memory blocks to
ranges. The supported columns are STATE, REMOVABLE, NODE and ZONES,
or "none". The other columns are silently ignored. For more details
see DESCRIPTION above.
-s, --sysroot directory
Gather memory data for a Linux instance other than the instance from
which the lsmem command is issued. The specified directory is the
system root of the Linux instance to be inspected.
--summary[=when]
This option controls summary lines output. The optional argument
when can be never, always or only. If the when argument is omitted,
it defaults to "only". The summary output is suppressed for --raw,
--pairs and --json.
-h, --help
Display help text and exit.
-V, --version
Display version and exit.
AUTHORS
lsmem was originally written by Gerald Schaefer for s390-tools in Perl.
The C version for util-linux was written by Clemens von Mann, Heiko
Carstens and Karel Zak.
SEE ALSO
chmem(8)
REPORTING BUGS
For bug reports, use the issue tracker
<https://github.com/util-linux/util-linux/issues>.
AVAILABILITY
The lsmem command is part of the util-linux package which can be
downloaded from Linux Kernel Archive
<https://www.kernel.org/pub/linux/utils/util-linux/>.
util-linux 2.41 2025-03-17 LSMEM(1)
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