checkmode

#!/bin/bash
# checkmodes
# 
# Print the status of DEC Private modes given on command line.
# If no arguments are given, checks all known modes.
#
# With -v flag, also show notes, if any.
# With -x flag, also print "Not recognized" for unrecognized modes.
# With -m flag, output as a Markdown table.
# With -t flag, trawl through modes 0 to 9999. 


# How long to wait for the terminal to reply, in seconds. (Non-integer okay).
#timeout=1.0

# By default, show double-wide frippery
fflag=yup

status=("not recognized" "set" "reset" "permanently set" "permanently reset")

checkmode() {
    # Given a DEC private mode number, query the terminal with DECRQM.
    # Prints a result from the 0 to 4. ([0]="not recognized" [1]="set"
    # [2]="reset" [3]="permanently set" [4]="permanently reset").
    #
    # If the terminal doesn't reply within ${timeout} seconds, prints
    # nothing and returns an error . (Default timeout is 0.25 seconds).
    
    IFS=";$" read -a REPLY -t${timeout:-0.25} -s -p $'\e[?'$1'$p' -d y \
	&& echo "${REPLY[1]}"
}

printmodes() {
    # Print the status of DEC Private modes given on command line.
    # With -v flag, also show notes.
    # With -x flag, also print "Not recognized" for unrecognized modes.

    # If no arguments given, check every known mode.
    if [[ $# -eq 0 ]]; then set - ${!Ps[@]}; fi

    if [[ -t 1  &&  $fflag ]]; then     # stdout is a terminal? let's go garish!
	local dw=$'\e#6'		# dw turns on double-wide characters
	status=( "$(tput dim)not recognized$(tput sgr0)$dw"
		 "$(tput bold)set$(tput sgr0)$dw"
		 "reset$dw"
		 "$(tput ul bold)permanently set$(tput sgr0)$dw"
		 "$(tput ul)permanently reset$(tput sgr0)$dw" )
    fi

    if [[ $vflag ]]; then
	local COLUMNS=$(tput cols)
	COLUMNS=${COLUMNS:-80}
    fi

    for mode; do
	if ! result=$(checkmode $mode); then
	    echo "Error: Terminal did not respond." >&2
	    exit 1
	fi

	# Skip "Not recognized", unless -x given, or only one arg.
	if [[ ${result} -ne 0  ||  $xflag  ||  $# -eq 1 ]]; then
	    echo "Checking mode #$mode. ${Ps[$mode]}"
	    echo "${status[result]}"
	    if [[ $vflag ]]; then
		echo ${Nt[mode]:--n} | fold -sw $((COLUMNS-24)) | sed 's/^/\t/'
	    fi
	fi
    done
}


maketable() {
    # Check the status of each DEC private mode given as an argument
    # and create a MarkDown table. Similar to printmodes() above. 
    # Allows -x flag to print "Not recognized" results.
    # Ignores -v, notes are always printed. 

    # If no arguments given, check every known mode.
    if [[ $# -eq 0 ]]; then set - ${!Ps[@]}; fi

    for mode; do
	if ! result=$(checkmode $mode); then
	    echo "Terminal did not respond to mode $mode." >&2
	else
 	    # Skip "Not recognized"
	    if [[ $result == 0 && -z "$xflag" ]]; then continue; fi
	    echo -n "$mode | "
	    echo -n "${status[result]}"
	    echo "| ${Ps[$mode]} | ${Nt[$mode]//|/\\|}"
	fi
    done
}


usage() {
    cat <<EOF
Usage:
  checkmode 			# Try all known DEC Private Modes 
  checkmode 80			# Request the status of mode 80.
  checkmode {1..100}  		# Request the status of modes 1 to 100.
  
Options:
-v, --show-notes		Show notes of unusual, surprising trivia
-x, --show-not-recognized	Do not skip modes the terminal doesn't recognize
-m, --output-markdown		Output a Markdown table instead of plain text
-t, --trawl			Try modes from 0 to 9999
-F, --no-frippery		Don't use double-wide chars or other frippery
EOF

}

main() {
    local TEMP

    if ! TEMP=$(
	    getopt -o 'vxmtFfh' \
		   --long 'show-notes' \
		   --long 'show-not-recognized' \
		   --long 'output-markdown' \
		   --long 'trawl' \
		   --long 'no-frippery' \
		   --long 'frippery' \
		   --long 'help' \
		   --name 'checkmode' -- "$@"); then
	# Invalid option error, so just quit.
	exit 1
    fi

    eval set -- "$TEMP"

    while true; do 
	case "$1" in
	    -v|--show-notes)
		vflag=yup
		shift
		;;
	    -x|--show-not-recognized)
		xflag=yup
		shift
		;;
	    -m|--output-markdown)
		mflag=yup
		shift
		;;
	    -t|--trawl)
		tflag=yup
		shift
		;;
	    -F|--no-frippery)
		fflag=""
		shift
		;;
	    -f|--frippery)
		fflag="yup"
		shift
		;;
	    '--')
		shift
		break
		;;
	    *)
		usage
		exit 1
		;;
	esac
    done

    if [[ $tflag ]]; then
	if [[ $# -eq 0 ]]; then
	    set -- {0..9999}
	else
	    echo "Warning: Ignoring --trawl since modes were specified" >&2
	fi
    fi

    if [[ -z $mflag ]]; then
	printmodes "$@"
    else
	maketable "$@"
    fi	
    # Return value is same as whichever function got run.
}


# Ps holds the array of DEC Private Mode. (See end for list of scoures.)
Ps=()
Ps[0]="Invalid mode"
	Nt[0]="Use of mode #0 is an error and always ignored."		# std-070
Ps[1]="Application Cursor Key Mode (DECCKM), VT100." # From std-070
	Nt[1]="When SET, arrow keys send special application commands to the host"
Ps[2]="Designate US ASCII/ANSI for character sets G0-G3 (DECANM), VT100." # From Xterm
Ps[2]="VT52 (ANSI) Mode (DECANM), VT100." 		# From ek-520-rm
	Nt[2]="To leave VT52 mode, use Esc <."
Ps[3]="132 Column Mode (DECCOLM), VT100."
	Nt[3]="VT340 docs claim DECCOLM is deprecated for DECSCPP (CSI 132 $ |). However, DECSCPP sets the columns per _page_, not screen. Unlike DECCOLM, DECSCPP does not change the visible number of columns on the screen; instead DECSCPP requires horizontal scrolling (see mode 60, DECHCCM)." # ek-vt3xx-tp
	Nt[3]+=" On the VT5x0, see mode 95 (DECNCSM) to prevent the page from being cleared by DECCOLM." # ek-520-rm
Ps[4]="Smooth (Slow) Scroll (DECSCLM), VT100."
	Nt[4]="On the VT340 and possibly other terminals, this option is not binary. In the SetUp menu, scrolling can be 'Jump' (same as RESET), or 'Smooth-1', '-2', or '-4' which scroll by scanlines instead of character cells. The VT340 factory default is 'Smooth-2', which is 25 scanlines (2.5 text lines) per second. Smooth-1 is half and Smooth-4 is twice the speed. If any of the Smooth options are selected, then the result from DECRQM (Request DEC Private Mode) will show mode 4 as SET. However, when mode 4 is SET using DECSET (CSI ? 4 h), the VT340 always selects Smooth-2. See also the VT5x0's DECSSCLS (Set Scroll Speed, CSI Ps SP p)."
Ps[5]="Reverse Video Screen (DECSCNM), VT100."
	Nt[5]="SET is light bg, RESET is dark bg." 	# From EK-VT38T-UG.
Ps[6]="Origin Mode (DECOM), VT100."
Ps[7]="Auto-Wrap Mode (DECAWM), VT100."
	Nt[7]="When RESET, cursor will not advance beyond right-most column."	# From std-070
Ps[8]="Auto-Repeat Keys (DECARM), VT100."
Ps[9]="Interlace mode (DECINLM), VT1xx only."   # Documented in VT100-UG
Ps[9]="Send Mouse X & Y on button press, X10 XTerm." # Conflicts with VT100-UG
	Nt[9]="VT100 used mode 9 for interlace, but dropped it in VT200+."
Ps[10]="Show toolbar, rxvt."			# Conflicts with ek-vt3xx-tp.
Ps[10]="Edit Mode (DECEDM)." 			# As documented by ek-vt3xx-tp.
Ps[11]="Line Transmit Mode (DECLTM)."	 	# Added from ek-vt3xx-tp.
Ps[12]="Start blinking cursor (AT&T 610)."	# Conflicts with ek-vt382-rm.
Ps[12]="Katakana Shift Mode (DECKANAM), VT382-J" # Documented in ek-vt382-rm.
Ps[13]="Start blinking cursor, xterm." 		# Conflicts with ek-vt3xx-tp.
Ps[13]="Space compression field delimiter (DECSCFDM)" # As documented by ek-vt3xx-tp.
Ps[14]="XOR of blinking cursor control sequence and menu." # Conflicts with ek-vt3xx-tp.
Ps[14]="Transmit execution (DECTEM)."	# As documented by ek-vt3xx-tp.

Ps[16]="Edit key execution (DECEKEM)."	# Added from ek-vt3xx-tp.

Ps[18]="Print Form Feed (DECPFF), VT220."
	Nt[18]="When SET, the terminal sends a form feed (FF) to the printer at the end of a printing function. The default, RESET, is to send to nothing. DECPFF does not affect the Print Cursor Line function."	# ek-vt3xx-tp
Ps[19]="Set printer extent to full screen (DECPEX), VT220."
	Nt[19]="When RESET, the print page function only prints the scrolling region (data inside the margins)."			# ek-vt3xx-tp
Ps[20]="Overstrike Mode (OS), VK100." 		# Documented in ek-vk100-tm-001
Ps[21]="Local BASIC Mode (BA), VK100." 		# Documented in ek-vk100-tm-001
Ps[22]="Host BASIC Mode (BA), VK100." 		# Documented in ek-vk100-tm-001
Ps[23]="Programmed Keypad Mode (PK), VK100." 	# Documented in ek-vk100-tm-001
Ps[24]="Auto Hardcopy Mode (AH), VK100."	# Documented in ek-vk100-tm-001
Ps[25]="Text cursor enable (DECTCEM), VT220."

Ps[27]="Proportional Spacing, printers."	# Added from ppl2

Ps[29]="Pitch Select Mode, printers."		# Added from ppl2

Ps[30]="Show scrollbar, rxvt."

Ps[34]="Cursor direction, right to left." 	# Added from ek-520-rm
Ps[35]="Tektronix mode (DECTEK), incorrect."	# As erroneously documented by ek-vt3xx-tp.
	Nt[35]="ek-vt3xx-tp is in error. DECTEK is actually 38."
Ps[35]="Font-shifting functions, rxvt."	# As documented by Xterm
Ps[35]="Hebrew keyboard mapping."	 	# Added from ek-520-rm
Ps[36]="Hebrew encoding mode."			# Added from ek-520-rm

Ps[38]="Tektronix mode (DECTEK), VT240, xterm."	# As documented by Xterm

Ps[40]="Allow 80/132 mode, xterm."			   # From xterm. Conflicts with ppl2.
	Nt[40]="Allow DECCOLM (mode 3) to switch columns."
Ps[40]="Carriage Return/New Line Mode (DECCRNLM), printers." # From ppl2
Ps[41]="more(1) fix."					     # From xterm. Conflicts with ppl2.
Ps[41]="Unidirectional Print Mode (DECUPM), printers."	     # From ppl2
	Nt[41]="Bidirectional when RESET."
Ps[42]="National Replacement Character sets (DECNRCM), VT220."
	Nt[42]="On the VT340 and perhaps other terminals, DECNRCM is PERMANENTLY RESET when the Keyboard Dialect selected in the Set Up menu is 'North American'."
Ps[43]="Graphics Expanded Print Mode (DECGEPM)."
Ps[44]="Margin bell, xterm."			# Conflicts with ek-vt3xx-tp.
Ps[44]="Graphics Print Color (DECGPCM)"		# As documented by ek-vt3xx-tp
Ps[45]="Reverse-wraparound mode, xterm."	# Conflicts with ek-vt3xx-tp.
Ps[45]="Graphics Print Color Space (DECGPCS)."	# As documented by Xterm.
Ps[45]="Graphics Print Color Syntax (DECGPCS)."	# As documented by ek-vt3xx-tp.
Ps[46]="Start logging, xterm."			# Conflicts with ek-vt3xx-tp.
Ps[46]="Graphics Print Background (DECGPBM)."	# As documented by ek-vt3xx-tp.
Ps[47]="Use Alternate Screen Buffer, xterm."	# Conflicts with ek-vt3xx-tp.
Ps[47]="Graphics Rotated Print Mode (DECGRPM)."	# As documented by ek-vt3xx-tp.

Ps[49]="Thai Keyboard Input Mode (DECTHAIM), VT382-T" 	# Added from ek-vt38t-ug
Ps[50]="Thai Cursor Mode (DECTHAICM), VT382-T" 	# Added from ek-vt38t-ug
	Nt[50]="SET is internal cursor, RESET is physical cursor"

Ps[53]="VT131 transmit (DEC131TM)."		# Added from ek-vt3xx-tp.

Ps[57]="North American / Greek keyboard mapping (DECNAKB)" 	# Added from ek-520-rm
Ps[58]="IBM ProPrinter Emulation (DECIPEM)" 	# Added from ek-520-rm
	Nt[58]="Interpret subsequent data according to the IBM ProPrinter protocol syntax instead of the DEC protocol."
Ps[59]="Kanji/Katakana Display Mode (DECKKDM), VT382-J"	# Documented in ek-vt382-rm.
Ps[60]="Horizontal cursor coupling (DECHCCM)."	# Added from ek-vt3xx-tp.
Ps[61]="Vertical cursor coupling (DECVCCM)."	# Added from ek-vt3xx-tp.

Ps[64]="Page cursor coupling (DECPCCM)."	# Added from ek-vt3xx-tp.

Ps[66]="Application/Numeric keypad mode (DECNKM), VT320"
Ps[67]="Backarrow key sends backspace (DECBKM), VT340, VT420, VT520."
	Nt[67]="When RESET (the default), backarrow key sends delete."
Ps[68]="Keyboard Usage: Data Processing or Typewriter Keys (DECKBUM)." # Added from ek-vt3xx-tp.
	Nt[68]="Data Processing characters are printed on the right half of the keycaps. According to ek-520-rm, 'If you use the North American language, then DECKBUM should always be RESET (typewriter). For all other languages, you can use either mode.'"
Ps[69]="Left and right margin mode (DECLRMM), VT420 and up." # Allows DECSLRM to set margins
Ps[69]="Vertical split screen / Left and right margin mode (DECVSSM/DECLRMM), VT420 and up." 	# Added from ek-520-rm. (Yes, it gives two different mnemonics!)

Ps[73]="Transmit rate limiting (DECXRLM)."	# Added from ek-vt3xx-tp.

Ps[80]="Sixel Display Mode (DECSDM)."
Ps[81]="Keyboard sends key position reports instead of character codes (DECKPM)." 	# Added from ek-520-rm
Ps[90]="Thai Space Compensating Mode (DECTHAISCM), VT382-T" # Added from ek-vt38t-ug

Ps[95]="Do not clear screen when DECCOLM is set/reset (DECNCSM), VT510 and up."
Ps[96]="Perform a copy/paste from right-to-left (DECRLCM), VT520" 	# Added from ek-520-rm
	Nt[96]="Only valid with Hebrew keyboard language, see DEC mode 35"
Ps[97]="CRT Save Mode (DECCRTSM), VT520" 	# Added from ek-520-rm
Ps[98]="Auto-resize the number of lines-per-page when the page arrangement changes (DECARSM), VT520" 	# Added from ek-520-rm
Ps[99]="Modem Control Mode: require DSR or CTS before communicating (DECMCM), VT520" 	# Added from ek-520-rm
Ps[100]="Send automatic answerback message 500ms after a communication line connection is made (DECAAM), VT520" 	# Added from ek-520-rm
Ps[101]="Conceal Answerback Message (DECCANSM), VT520" 	# Added from ek-520-rm
Ps[102]="Discard NUL characters upon receipt, or pass them on to the printer (DECNULM)" 	# Added from ek-520-rm
Ps[103]="Half-Duplex Mode (DECHDPXM), VT520" 	# Added from ek-520-rm
Ps[104]="Enable Secondary Keyboard Language (DECESKM), VT520" 	# Added from ek-520-rm

Ps[106]="Overscan mode for monochrome VT520 terminal (DECOSCNM)" 	# Added from ek-520-rm

Ps[108]="Num Lock Mode of keyboard (DECNUMLK)"		# Added from ek-520-rm
Ps[109]="Caps Lock Mode of keyboard (DECCAPSLK)" 	# Added from ek-520-rm
Ps[110]="Keyboard LED's Host Indicator Mode (DECKLHIM)"	# Added from ek-520-rm
Ps[111]="Framed Windows with title bars, borders, and icons (DECFWM), VT520" 	# Added from ek-520-rm
Ps[112]="Allow user to Review Previous Lines that have scrolled off the top (DECRPL)" 	# Added from ek-520-rm
Ps[113]="Host Wake-up Mode, CRT and Energy Saver (DECHWUM), VT520" 	# Added from ek-520-rm
Ps[114]="Use an alternate text color for underlined text (DECATCUM), VT520" 	# Added from ek-520-rm
Ps[115]="Use an alternate text color for blinking text (DECATCMB), VT520" 	# Added from ek-520-rm
Ps[116]="Bold and blink styles affect background as well as foreground (DECBSM), VT520" 	# Added from ek-520-rm
Ps[117]="Erase Color is screen background (VT) or text background (PC) (DECECM), VT520" 	# Added from ek-520-rm
	Nt[117]="Background color used when text is erased or new text is scrolled on to the screen"

Ps[1000]="Send Mouse X & Y on button press and release. (X11 XTerm mouse)."
Ps[1001]="Use Hilite Mouse Tracking, xterm."
Ps[1002]="Use Cell Motion Mouse Tracking, xterm."
Ps[1003]="Use All Motion Mouse Tracking, xterm."
Ps[1004]="Send FocusIn/FocusOut events, xterm."
Ps[1005]="UTF-8 Mouse Mode, xterm."
Ps[1006]="SGR Mouse Mode, xterm."
Ps[1007]="Alternate Scroll Mode, xterm."

Ps[1010]="Scroll to bottom on tty output, rxvt."
Ps[1011]="Scroll to bottom on key press, rxvt."
Ps[1015]="Urxvt Mouse Mode, rxvt."
Ps[1016]="SGR Mouse PixelMode, xterm."
Ps[1021]="High intensity bold/blink color, rxvt." 	# From VTE modes.py
Ps[1034]="Interpret 'Meta' key, xterm."
	Nt[1034]="This sets the eighth bit of keyboard input."
Ps[1035]="Enable special modifiers for Alt and NumLock keys, xterm."
Ps[1036]="Send ESC when Meta modifies a key, xterm."
Ps[1037]="Send DEL from the editing-keypad Delete key, xterm."
Ps[1039]="Send ESC when Alt modifies a key, xterm."
Ps[1040]="Keep selection even if not highlighted, xterm."
Ps[1041]="Use the CLIPBOARD selection, xterm."
Ps[1042]="Enable Urgency windowmanager hint when Control-G received, xterm."
Ps[1043]="Enable raising of the window when Control-G is received, xterm."
Ps[1044]="Reuse the most recent data copied to CLIPBOARD, xterm"
Ps[1046]="Enable switching to/from Alternate Screen Buffer, xterm."
Ps[1047]="Use Alternate Screen Buffer, xterm."
Ps[1048]="Save cursor as in DECSC, xterm."
Ps[1049]="Save cursor as in DECSC, switch to the Alternate Screen Buffer."
Ps[1050]="Set terminfo/termcap function-key mode, xterm."
Ps[1051]="Set Sun function-key mode, xterm."
Ps[1052]="Set HP function-key mode, xterm."
Ps[1053]="Set SCO function-key mode, xterm."
Ps[1060]="Set legacy keyboard emulation, i.e, X11R6, xterm."
Ps[1061]="Set VT220 keyboard emulation, xterm."
Ps[1070]="Use private color registers for each graphic, xterm."
	Nt[1070]="When SET, each Sixel/ReGIS graphic gets a fresh palette. When RESET, colormap changes persist just like on a true VT340. SET is the default for XTerm."
Ps[2004]="Set bracketed paste mode, xterm."
Ps[2026]="Synchronized output. iTerm2, Contour, Kitty." # From https://gist.github.com/christianparpart/d8a62cc1ab659194337d73e399004036
	Nt[2026]="When SET, new data is not displayed until the mode is RESET. Can be used by applications for double-buffering & page flipping to prevent screen tearing."
Ps[8452]="Sixel leaves cursor right of image, RLogin, xterm."


# Okay, all the definitions are set. Topple them dominos!
main "$@"



# Sources (most frequently used first) for DEC private modes:
#	XTerm ctlseqs.pdf (default if not otherwise marked)
# 	VT520/525 Reference Manual		ek-520-rm
# 	VT300 Text Programming	 		ek-vt3xx-tp
#	DEC STD 070				std-070
#	VK100 Technical Manual			ek-vk100-tm
# 	VT382-J (Japanese) Reference Manual	ek-vt382-rm
#	VT382-T (Thai) User Guide		ek-vt38t-ug
#	VT100 User Guide 			VT100-UG
#	DEC Printing Protocol Level 2 quickref	ppl2
#	LG06/LG12 Companion Printer		lg12
# Missing manuals:
#	VT382-K (Korean)
#	VT382-D (Traditional Chinese)
#	VT382-C (Simplified Chinese))
#	VT282-J, VT382-J, VT383-J, VT284-J, VT286-J (Japanese terminals)