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LSCLOCKS(1) User Commands LSCLOCKS(1)

NAME

lsclocks - display system clocks

SYNOPSIS

lsclocks [option]

DESCRIPTION

lsclocks is a simple command to display system clocks.

It allows to display information like current time and resolution of clocks. Different kinds of clocks are supported.

•POSIX clocks: CLOCK_MONOTONIC, CLOCK_REALTIME, CLOCK_BOOTTIME, etc.

•CPU clocks: clock_getcpuclockid(3).

•PTP clocks: /dev/ptp0.

•RTC clocks: /dev/rtc0.

•Auxiliary clocks: CLOCK_AUX0, CLOCK_AUX1, etc.

OPTIONS

-J, --json

Use JSON output format.

-n, --noheadings

Don’t print headings.

-o, --output list

Specify which output columns to print. See the OUTPUT COLUMNS section for details of available columns.

--output-all

Output all columns.

-r, --raw

Use raw output format.

-t, --time clock

Show current time of one specific clock.

--no-discover-dynamic

Do not try to discover dynamic clocks.

-d, --dynamic-clock path

Also display specified dynamic clock. Can be specified multiple times.

--no-discover-rtc

Do not try to discover RTCs.

-x, --rtc path

Also display specified RTC. Can be specified multiple times.

-c, --cpu-clock pid

Also display CPU clock of specified process. Can be specified multiple times.

-h, --help

Display help text and exit.

-V, --version

Display version and exit.

ENVIRONMENT

LSCLOCKS_COLUMNS=

Specifies a comma-separated list of output columns to print. All columns listed in OUTPUT COLUMNS can be used.

LIBSMARTCOLS_DEBUG=all

enables libsmartcols debug output.

LIBSMARTCOLS_DEBUG_PADDING=on

use visible padding characters.

LIBSMARTCOLS_JSON=compact|lines

Controls JSON output format when using --json. Supported values are compact for JSON output with minimal whitespace, and lines for JSON Lines format (one JSON object per line). If unset or set to any other value, pretty-printed JSON is used.

OUTPUT COLUMNS

Each column has a type. Types are surround by < and >.

TYPE <string>

Clock type.

ID <number>

Numeric clock ID.

CLOCK <string>

Name in the form CLOCK_

NAME <string>

Shorter, easier to read name.

TIME <number>

Current clock timestamp as returned by clock_gettime(2).

ISO_TIME <string>

ISO8601 formatted version of TIME.

RESOL_RAW <number>

Clock resolution as returned by clock_getres(2).

RESOL <number>

Human readable version of RESOL_RAW.

REL_TIME <string>

TIME time formatted as time range.

NS_OFFSET <number>

Offset of the current namespace to the parent namespace as read from /proc/self/timens_offsets.

AUTHORS

Thomas Weißschuh <thomas@t-8ch.de>

SEE ALSO

clock_getres(2) clock_gettime(2)

REPORTING BUGS

For bug reports, use the issue tracker <https://github.com/util-linux/util-linux/issues>.

AVAILABILITY

The lsclocks 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/>.

2026-03-19 util-linux 2.42-rc2