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#!/bin/bash --noprofile |
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# DO ALMOST ANYTHING PUBLIC LICENSE |
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# Everyone is permitted to copy and distribute verbatim or modified |
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# copies of this code for any purpose as long as any "Credit" |
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# lines are not removed. |
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#Credit: /u/linuxversion |
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#<your Credit line here, if you want> |
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#extra strict flags |
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set -euo pipefail |
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#so I don't accidently forget whats builtin and whats not |
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PATH='' |
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#configuration options |
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declare -i cfg_line_numbers=1 |
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#globals |
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declare -a file_map |
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declare -i file_offset=0 |
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declare -i file_lines=0 |
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declare -i term_height=0 |
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declare -i term_width=0 |
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declare -i textarea_height=0 |
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declare -i textarea_line=0 |
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declare -i command_line=0 |
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#move the cursor to a specific row and colunm |
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function put_cursor() { |
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echo -en "\e[${1};${2}f" |
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} |
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#basically the same as the libncurses function of the same name |
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function mvprintw() { |
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local row="$1"; shift |
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local col="$1"; shift |
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printf "%s%s%s" $'\x1b[' "${row};${col}f" "$@" |
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} |
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#self-explanitory |
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function clear_screen() { |
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echo -en '\e[2J' |
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} |
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#erase text from command line to bottom of screen |
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function clear_command_line() { |
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mvprintw "$command_line" 0 $'\x1b[J' |
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} |
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function init_screen() { |
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#set terminal configuration to default |
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#echo -en '\ec' |
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#get the size of the terminal |
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put_cursor 999 999 |
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echo -en '\e[6n' |
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read -s -r -d'[' |
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read -s -r -d';' term_height |
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read -s -r -d'R' term_width |
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#do some math to position the various graphical elements |
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textarea_line=0 |
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textarea_height=$term_height |
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command_line=$term_height |
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clear_screen |
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put_cursor "$command_line" 0 |
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} |
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#draw text on the screen from memory with offset |
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function render_text() { |
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clear_screen |
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#figure out how many lines we can render |
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local modifier="$1" |
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local lines=$textarea_height |
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local last_screen=$((file_lines - textarea_height)) |
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file_offset=$((file_offset + modifier)) |
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[ $file_offset -gt $last_screen ] && file_offset=$last_screen |
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[ $file_offset -lt 0 ] && file_offset=0 |
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[ $lines -gt $file_lines ] && lines=$file_lines |
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#draw text in the viewing area |
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local fd_offset |
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local term_offset |
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for (( i=0; i<lines; ++i )) |
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do |
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fd_offset=$((i+file_offset)) |
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term_offset=$((i+textarea_line)) |
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[ $cfg_line_numbers -eq 1 ] && { |
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mvprintw "${term_offset}" 0 "${fd_offset}" |
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mvprintw "${term_offset}" 6 "${file_map[$fd_offset]}" |
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} || { |
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mvprintw "${term_offset}" 0 "${file_map[$fd_offset]}" |
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} |
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done |
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} |
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function main() { |
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#arg check |
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if (( $# > 0 )) && [ -f "$1" ] |
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then |
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mapfile file_map <"$1" |
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else |
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echo 'Usage: bash_pager <file>' |
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return 1 |
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fi |
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file_lines="${#file_map[@]}" |
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init_screen |
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render_text 0 |
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#read keys and perform actions |
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while read -s -r -N1 |
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do |
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case "$REPLY" in |
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( $'\x1b' ) #ESC pressed, handle sequence |
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read -s -r -N1 |
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case "$REPLY" in |
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( $'\x1b' ) #second escape, eval user input |
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read -e -r -p ': ' |
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set +eu |
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eval "$REPLY" |
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set -eu |
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;; |
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( '[' ) #arrow key or pgup/pgdown |
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read -s -r -N1 |
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case "$REPLY" in |
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( 'A' ) #arrow up |
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render_text -1 |
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;; |
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( 'B' ) #arrow down |
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render_text 1 |
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;; |
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( '5' ) #pgup |
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render_text "-$((textarea_height/2))" |
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;; |
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( '6' ) #pgdown |
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render_text "$((textarea_height/2))" |
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;; |
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esac |
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;; |
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esac |
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;; |
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( 'q' ) #quit |
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return 0 |
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;; |
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esac |
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#input keys have been read display results |
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clear_command_line |
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put_cursor "$command_line" 0 |
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done |
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} |
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main $@ |
dubiouscript revised this gist
SomeCrazyGuy created this gist