3パターンある
xrandr
例)
tyano ~$ xrandr --verbose | grep -i connected
DP-1 disconnected (normal left inverted right x axis y axis)
HDMI-1 disconnected (normal left inverted right x axis y axis)
HDMI-2 connected 1920x1080+0+0 (0x48) normal (normal left inverted right x axis y axis) 527mm x 296mm
DP-2 disconnected (normal left inverted right x axis y axis)
HDMI-3 disconnected (normal left inverted right x axis y axis)
hwinfo
例)
tyano ~$ hwinfo --monitor | grep -i size
Size: 527x296 mm
edid-decode
例)
tyano ~$ cat /sys/class/drm/*/edid | edid-decode | grep DTD
DTD 1: 1920x1080 60.000000 Hz 16:9 67.500 kHz 148.500000 MHz (527 mm x 296 mm)
DTD 2: 1920x1080i 60.000000 Hz 16:9 33.750 kHz 74.250000 MHz (527 mm x 296 mm)
DTD 3: 1280x720 60.000000 Hz 16:9 45.000 kHz 74.250000 MHz (527 mm x 296 mm)
DTD 4: 720x480 59.940060 Hz 3:2 31.469 kHz 27.000000 MHz (527 mm x 296 mm)
計算
1inch = 25.4mmなので
https://www.wolframalpha.com/input?i==sqrt(527^2+296^2)/25.4
firefoxだとurlエンコードは勝手にやってくれる
ほかのブラウザだと分かりません
もしくはhttps://www.wolframalpha.com/にアクセスして以下のように入力
=sqrt(527^2+296^2)/25.4