79 lines
2.4 KiB
Plaintext
79 lines
2.4 KiB
Plaintext
EVTEST(1)
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=========
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NAME
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----
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evtest - Input device event monitor and query tool
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SYNOPSIS
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--------
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evtest [--grab] /dev/input/eventX
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evtest --query /dev/input/eventX <type> <value>
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DESCRIPTION
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-----------
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The first invocation type displayed above ("capture mode") causes evtest to
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display information about the specified input device, including all the events
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supported by the device. It then monitors the device and displays all the
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events layer events generated.
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If the --grab flag is given in capture mode, evtest keeps an EVIOCGRAB on the
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device. While this grab is active, other processes will not receive events
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from the kernel devices. The grab is released again when evtest quits.
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In the second invocation type ("query mode"), evtest performs a one-shot query
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of the state of a specific key *value* of an event *type*.
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*type* is one of: *EV_KEY*, *EV_SW*, *EV_SND*, *EV_LED* (or the numerical value)
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*value* can be either a decimal representation (e.g. 44), hex
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(e.g. 0x2c), or the constant name (e.g. KEY_Z) of the key/switch/sound/LED
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being queried.
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If the state bit is set (key pressed, switch on, ...), evtest exits with
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code 10. If the state bit is unset (key depressed, switch off, ...), evtest
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exits with code 0. No other output is generated.
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evtest needs to be able to read from the device; in most cases this means it
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must be run as root.
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evtest is commonly used to debug issues with input devices in X.Org. The
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output of evtest shows the information presented by the kernel; based on
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this information it can be determined whether a bug may be a kernel or an
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X.Org issue.
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DIAGNOSTICS
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-----------
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If evtest does not show any events even though the device is being used, the
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device may be grabbed by a process (EVIOCGRAB). This is usually the case
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when debugging a synaptics device from within X. VT switching to a TTY or
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shutting down the X server terminates this grab and synaptics devices can be
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debugged.
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The following command shows the processes with an open file descriptor on
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the device:
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fuser -v /dev/input/eventX
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EXIT CODE
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---------
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evtest returns 1 on error.
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When used to query state, evtest returns 0 if the state bit is unset and
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10 if the state bit is set.
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SEE ALSO
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--------
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inputattach(1)
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AUTHOR
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------
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evtest was written by Vojtech Pavlik <vojtech@suse.cz>.
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This manual page was written by Stephen Kitt <steve@sk2.org>, based on that
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present in the lineakd package, for the Debian GNU/Linux system (but may be
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used by others).
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