mode2 man page

mode2 — Show pulse/space length or decoded input from infrared drivers.


mode2 --driver <driver> [--device <device>] [other options]

mode2 --raw --device <device> [other options]

mode2 --driver <driver>  --list-devices


The main purpose of this program is to check operation of your home-brew LIRC receiver hardware and to see the IR waveform of the remote controller without an expensive oscilloscope. Very useful for debugging also in situations you just need to verify configuration.

mode2 will simply print pulse and space lengths to stdout for drivers supporting LIRC_MODE_MODE2. For drivers supporting LIRC_MODE_LIRCCODE such as TV-cards and the irman driver writes the decoded, integer values.

When given the correct driver mode2 should always work. Without a driver, the --raw option should always work for /dev/lirc* devices. At the time of writing, usb devices also works in most cases. However, since it is tricky to get the path to the usb device, such ones are normally best accessed using a driver.

Not all drivers requires a device.


-d --device=device

Read from given device.

-H --driver=driver

Use given driver.

-m --mode

Write pulse/space data as raw config files. Does not affect LIRCCODE drivers.

-s --scope=time

Enable 'scope like display with time us per char. Does not affect lirccode drivers.

-k --keep-root

Don't drop root privileges after opening device. See Running As Root.

-l --list-devices

List all available devices for given driver. Requires support not present in all drivers.

-g --gap=time

Treat spaces longer than time as the gap. Time is in microseconds.

-r --raw

Access device directly. This is primarely intended to be used with kernel rc drivers i .e., when accessing /dev/lirc* devices. Using other devices might work, but is in general undefined.

-A --driver-options=key:value[|key:value...]

Set driver-specific option named key to given value.

-U --plugindir=directory

Load drivers from directory. See Driver Loading.

-O, --options-file <path>

File containing default values for all options. A relative path is interpreted from current directory. See [Files] below.

-D --loglevel=level

Determine the amount of logging information. [level] can be a symbolic syslog level: 'error','warning, 'info', 'notice' or  'debug'. lirc also defines three additional levels 'trace', 'trace1' and 'trace2' which gives even more messages ('trace2' bringing the most). However, in the log these messages are marked as 'debug'. The level can also be an integer in the range 3 (almost no messages) to 10.

-h --help

Display usage summary.

-v --version

Display version.

Running As Root

In many cases mode2 needs to run as root to access devices not available to regular users. On the other hand, running as root creates problems such as log files owned by root, security concerns etc.

In order to cope with this, mode2 by default drops root privileges after opening the input device. This support is based on that root permissions are accquired using sudo(1) e. g., using

        $ sudo mode2 --raw /dev/lirc0

If not using sudo, the same behaviour could be accomplished using the SUDO_USER environment variable e. g.,

        # SUDO_USER=$LOGNAME mode2 --raw /dev/lirc0

The --keep-root option will make mode2 to keep root privileges for the complete run.


Invoked with a MODE2 type driver with mode2 prints space/mark timings:

     al@snorken $ ./mode2 --driver default --device /dev/lirc0
     Using driver default on device /dev/lirc0
     Trying device: /dev/lirc0
     Using device: /dev/lirc0
     pulse 2750
     space 800
     pulse 500
     space 350
     pulse 550
     space 350
     pulse 550

Invoked with a LIRCCODE type driver mode2 prints decoded values:

     $ ./mode2 --driver atilibusb
     Using driver atilibusb on device /dev/lirc0
     Trying device: /dev/bus/usb/001/007
     Using device: /dev/bus/usb/001/007
     code: 0x14709b0000
     code: 0x14709b0000
     code: 0x14709b0000
     code: 0x14709b0000
     code: 0x14709b0000

Driver Loading

Drivers are loaded dynamically. The search path used for this is determined by (falling priority):



Used as fallback when there is no --loglevel option present. Syntax is the same as for --loglevel, see Options.



The options file holding default values for command line options in the [mode2] section. For some values including debug, plugindir, driver and device mode2 falls back to the [lircd] section if not found in [mode2].

The location of this file can be changed using the -O/--options-file command-line option or using the environment variable LIRC_OPTIONS_PATH.


Debug log. Setting the XDG_CACHE_HOME environment variable relocates this file to $XDG_CACHE_HOME/mode2.log. The amount of logging respects the LIRC_LOGLEVEL environment variable, defaulting to the debug value in lirc_options.conf.

See Also


The documentation for lirc is maintained as html pages. They are located under html/ in the documentation directory.

Referenced By

irpipe(1), irrecord(1), irsend(1), irtestcase(1), irtext2udp(1), lircd(8), xmode2(1).

Last change: Oct 2015 mode2 0.9.4c User Commands