tvservice
tvservice is a command line application used to get and set information about the display, targeted mainly at HDMI video and audio.
Typing tvservice by itself will display a list of available command line options.
Options
-p, --preferred
Power on the HDMI output with preferred settings.
-o, --off
Powers off the display output.
Important Note: Powering off the output using this command will also destroy any framebuffers/dispmanx layers associated with the display. These are NOT re-established with a subsequent power on, so will result in a blank screen.
A better option is to use the vcgencmd display_power option, as this will retain any framebuffers, so when the power is turned back on the display will be the returned to the previous power on state.
-e, --explicit="Group Mode Drive"
Power on the HDMI with the specified settings
Group can be one of CEA, DMT, CEA_3D_SBS, CEA_3D_TB, CEA_3D_FP, CEA_3D_FS.
Mode is one of the modes returned from the -m, --modes option.
Drive can be one of HDMI, DVI.
-t, --ntsc
Use 59.94Hz (NTSC frequency) rather than 60Hz for HDMI mode.
-c, --sdtvon="Mode Aspect [P]"
Power on the SDTV (composite output) with the specified mode, PAL or NSTC, and the specified aspect, 4:3, 14:9, 16:9. The optional P parameter can be used to specify progressive mode.
-m, --modes=Group
where Group is CVT or DMT.
Shows a list of display modes available in the specified group.
-M, --monitor
Monitors for any HDMI events, for example unplugging or attaching.
-s, --status
Shows the current settings for the display mode, including mode, resolution, and frequency.
-a, --audio
Shows the current settings for the audio mode, including channels, sample rate and sample size.
-d, --dumpid=filename
Save the current EDID to the specified filename. You can then use edidparser <filename> to display the data in a human readable form.
-j, --json
When used in combination with the --modes options, displays the mode information in JSON format.
-n, --name
Extracts the display name from the EDID data and shows it.