1 /* vi: set sw=4 ts=4: */
3 * Mini less implementation for busybox
5 * Copyright (C) 2005 by Rob Sullivan <cogito.ergo.cogito@gmail.com>
7 * Licensed under GPLv2 or later, see file LICENSE in this source tree.
12 * - Add more regular expression support - search modifiers, certain matches, etc.
13 * - Add more complex bracket searching - currently, nested brackets are
15 * - Add support for "F" as an input. This causes less to act in
16 * a similar way to tail -f.
17 * - Allow horizontal scrolling.
20 * - the inp file pointer is used so that keyboard input works after
21 * redirected input has been read from stdin
28 //config: 'less' is a pager, meaning that it displays text files. It possesses
29 //config: a wide array of features, and is an improvement over 'more'.
31 //config:config FEATURE_LESS_MAXLINES
32 //config: int "Max number of input lines less will try to eat"
33 //config: default 9999999
34 //config: depends on LESS
36 //config:config FEATURE_LESS_BRACKETS
37 //config: bool "Enable bracket searching"
39 //config: depends on LESS
41 //config: This option adds the capability to search for matching left and right
42 //config: brackets, facilitating programming.
44 //config:config FEATURE_LESS_FLAGS
45 //config: bool "Enable -m/-M"
47 //config: depends on LESS
49 //config: The -M/-m flag enables a more sophisticated status line.
51 //config:config FEATURE_LESS_TRUNCATE
52 //config: bool "Enable -S"
54 //config: depends on LESS
56 //config: The -S flag causes long lines to be truncated rather than
59 //config:config FEATURE_LESS_MARKS
60 //config: bool "Enable marks"
62 //config: depends on LESS
64 //config: Marks enable positions in a file to be stored for easy reference.
66 //config:config FEATURE_LESS_REGEXP
67 //config: bool "Enable regular expressions"
69 //config: depends on LESS
71 //config: Enable regular expressions, allowing complex file searches.
73 //config:config FEATURE_LESS_WINCH
74 //config: bool "Enable automatic resizing on window size changes"
76 //config: depends on LESS
78 //config: Makes less track window size changes.
80 //config:config FEATURE_LESS_ASK_TERMINAL
81 //config: bool "Use 'tell me cursor position' ESC sequence to measure window"
83 //config: depends on FEATURE_LESS_WINCH
85 //config: Makes less track window size changes.
86 //config: If terminal size can't be retrieved and $LINES/$COLUMNS are not set,
87 //config: this option makes less perform a last-ditch effort to find it:
88 //config: position cursor to 999,999 and ask terminal to report real
89 //config: cursor position using "ESC [ 6 n" escape sequence, then read stdin.
91 //config: This is not clean but helps a lot on serial lines and such.
93 //config:config FEATURE_LESS_DASHCMD
94 //config: bool "Enable flag changes ('-' command)"
96 //config: depends on LESS
98 //config: This enables the ability to change command-line flags within
99 //config: less itself ('-' keyboard command).
101 //config:config FEATURE_LESS_LINENUMS
102 //config: bool "Enable dynamic switching of line numbers"
104 //config: depends on FEATURE_LESS_DASHCMD
106 //config: Enables "-N" command.
108 //usage:#define less_trivial_usage
109 //usage: "[-E" IF_FEATURE_LESS_REGEXP("I")IF_FEATURE_LESS_FLAGS("Mm")
110 //usage: "N" IF_FEATURE_LESS_TRUNCATE("S") "h~] [FILE]..."
111 //usage:#define less_full_usage "\n\n"
112 //usage: "View FILE (or stdin) one screenful at a time\n"
113 //usage: "\n -E Quit once the end of a file is reached"
114 //usage: IF_FEATURE_LESS_REGEXP(
115 //usage: "\n -I Ignore case in all searches"
117 //usage: IF_FEATURE_LESS_FLAGS(
118 //usage: "\n -M,-m Display status line with line numbers"
119 //usage: "\n and percentage through the file"
121 //usage: "\n -N Prefix line number to each line"
122 //usage: IF_FEATURE_LESS_TRUNCATE(
123 //usage: "\n -S Truncate long lines"
125 //usage: "\n -~ Suppress ~s displayed past EOF"
127 #include <sched.h> /* sched_yield() */
130 #include "common_bufsiz.h"
131 #if ENABLE_FEATURE_LESS_REGEXP
137 /* The escape codes for highlighted and normal text */
138 #define HIGHLIGHT ESC"[7m"
139 #define NORMAL ESC"[0m"
140 /* The escape code to home and clear to the end of screen */
141 #define CLEAR ESC"[H\033[J"
142 /* The escape code to clear to the end of line */
143 #define CLEAR_2_EOL ESC"[K"
146 /* Absolute max of lines eaten */
147 MAXLINES = CONFIG_FEATURE_LESS_MAXLINES,
148 /* This many "after the end" lines we will show (at max) */
152 /* Command line options */
160 FLAG_S = (1 << 6) * ENABLE_FEATURE_LESS_TRUNCATE,
161 /* hijack command line options variable for internal state vars */
162 LESS_STATE_MATCH_BACKWARDS = 1 << 15,
165 #if !ENABLE_FEATURE_LESS_REGEXP
166 enum { pattern_valid = 0 };
170 int cur_fline; /* signed */
171 int kbd_fd; /* fd to get input from */
173 /* last position in last line, taking into account tabs */
174 size_t last_line_pos;
176 unsigned max_lineno; /* this one tracks linewrap */
177 unsigned max_displayed_line;
179 #if ENABLE_FEATURE_LESS_WINCH
180 unsigned winch_counter;
182 ssize_t eof_error; /* eof if 0, error if < 0 */
184 ssize_t readeof; /* must be signed */
187 const char *empty_line_marker;
189 unsigned current_file;
192 #if ENABLE_FEATURE_LESS_FLAGS
193 int num_lines; /* a flag if < 0, line count if >= 0 */
194 # define REOPEN_AND_COUNT (-1)
195 # define REOPEN_STDIN (-2)
196 # define NOT_REGULAR_FILE (-3)
198 #if ENABLE_FEATURE_LESS_MARKS
200 unsigned mark_lines[15][2];
202 #if ENABLE_FEATURE_LESS_REGEXP
203 unsigned *match_lines;
204 int match_pos; /* signed! */
205 int wanted_match; /* signed! */
208 smallint pattern_valid;
210 #if ENABLE_FEATURE_LESS_ASK_TERMINAL
211 smallint winsize_err;
214 struct termios term_orig, term_less;
215 char kbd_input[KEYCODE_BUFFER_SIZE];
217 #define G (*ptr_to_globals)
218 #define cur_fline (G.cur_fline )
219 #define kbd_fd (G.kbd_fd )
220 #define less_gets_pos (G.less_gets_pos )
221 #define last_line_pos (G.last_line_pos )
222 #define max_fline (G.max_fline )
223 #define max_lineno (G.max_lineno )
224 #define max_displayed_line (G.max_displayed_line)
225 #define width (G.width )
226 #define winch_counter (G.winch_counter )
227 /* This one is 100% not cached by compiler on read access */
228 #define WINCH_COUNTER (*(volatile unsigned *)&winch_counter)
229 #define eof_error (G.eof_error )
230 #define readpos (G.readpos )
231 #define readeof (G.readeof )
232 #define buffer (G.buffer )
233 #define flines (G.flines )
234 #define empty_line_marker (G.empty_line_marker )
235 #define num_files (G.num_files )
236 #define current_file (G.current_file )
237 #define filename (G.filename )
238 #define files (G.files )
239 #define num_lines (G.num_lines )
240 #define num_marks (G.num_marks )
241 #define mark_lines (G.mark_lines )
242 #if ENABLE_FEATURE_LESS_REGEXP
243 #define match_lines (G.match_lines )
244 #define match_pos (G.match_pos )
245 #define num_matches (G.num_matches )
246 #define wanted_match (G.wanted_match )
247 #define pattern (G.pattern )
248 #define pattern_valid (G.pattern_valid )
250 #define terminated (G.terminated )
251 #define term_orig (G.term_orig )
252 #define term_less (G.term_less )
253 #define kbd_input (G.kbd_input )
254 #define INIT_G() do { \
255 SET_PTR_TO_GLOBALS(xzalloc(sizeof(G))); \
256 less_gets_pos = -1; \
257 empty_line_marker = "~"; \
262 IF_FEATURE_LESS_REGEXP(wanted_match = -1;) \
265 /* flines[] are lines read from stdin, each in malloc'ed buffer.
266 * Line numbers are stored as uint32_t prepended to each line.
267 * Pointer is adjusted so that flines[i] points directly past
268 * line number. Accesor: */
269 #define MEMPTR(p) ((char*)(p) - 4)
270 #define LINENO(p) (*(uint32_t*)((p) - 4))
273 /* Reset terminal input to normal */
274 static void set_tty_cooked(void)
277 tcsetattr(kbd_fd, TCSANOW, &term_orig);
280 /* Move the cursor to a position (x,y), where (0,0) is the
281 top-left corner of the console */
282 static void move_cursor(int line, int row)
284 printf(ESC"[%u;%uH", line, row);
287 static void clear_line(void)
289 printf(ESC"[%u;0H" CLEAR_2_EOL, max_displayed_line + 2);
292 static void print_hilite(const char *str)
294 printf(HIGHLIGHT"%s"NORMAL, str);
297 static void print_statusline(const char *str)
300 printf(HIGHLIGHT"%.*s"NORMAL, width - 1, str);
303 /* Exit the program gracefully */
304 static void less_exit(int code)
309 kill_myself_with_sig(- code); /* does not return */
313 #if (ENABLE_FEATURE_LESS_DASHCMD && ENABLE_FEATURE_LESS_LINENUMS) \
314 || ENABLE_FEATURE_LESS_WINCH
315 static void re_wrap(void)
321 int new_cur_fline = 0;
324 const char **old_flines = flines;
326 char **new_flines = NULL;
329 if (option_mask32 & FLAG_N)
342 if (*d == '\t') { /* tab */
344 new_line_pos &= (~7);
348 if (new_line_pos >= w) {
350 /* new line is full, create next one */
353 sz = (d - linebuf) + 1; /* + 1: NUL */
354 d = ((char*)xmalloc(sz + 4)) + 4;
356 memcpy(d, linebuf, sz);
357 new_flines = xrealloc_vector(new_flines, 8, dst_idx);
358 new_flines[dst_idx] = d;
360 if (new_line_pos < w) {
361 /* if we came here thru "goto next_new" */
362 if (src_idx > max_fline)
371 /* *d == NUL: old line ended, go to next old one */
372 free(MEMPTR(old_flines[src_idx]));
373 /* btw, convert cur_fline... */
374 if (cur_fline == src_idx)
375 new_cur_fline = dst_idx;
377 /* no more lines? finish last new line (and exit the loop) */
378 if (src_idx > max_fline)
380 s = old_flines[src_idx];
381 if (lineno != LINENO(s)) {
382 /* this is not a continuation line!
383 * create next _new_ line too */
389 flines = (const char **)new_flines;
391 max_fline = dst_idx - 1;
392 last_line_pos = new_line_pos;
393 cur_fline = new_cur_fline;
394 /* max_lineno is screen-size independent */
395 #if ENABLE_FEATURE_LESS_REGEXP
401 #if ENABLE_FEATURE_LESS_REGEXP
402 static void fill_match_lines(unsigned pos);
404 #define fill_match_lines(pos) ((void)0)
407 static int at_end(void)
409 return (option_mask32 & FLAG_S)
410 ? !(cur_fline <= max_fline &&
411 max_lineno > LINENO(flines[cur_fline]) + max_displayed_line)
412 : !(max_fline > cur_fline + max_displayed_line);
415 /* Devilishly complex routine.
417 * Has to deal with EOF and EPIPE on input,
418 * with line wrapping, with last line not ending in '\n'
419 * (possibly not ending YET!), with backspace and tabs.
420 * It reads input again if last time we got an EOF (thus supporting
421 * growing files) or EPIPE (watching output of slow process like make).
424 * flines[] - array of lines already read. Linewrap may cause
425 * one source file line to occupy several flines[n].
426 * flines[max_fline] - last line, possibly incomplete.
427 * terminated - 1 if flines[max_fline] is 'terminated'
428 * (if there was '\n' [which isn't stored itself, we just remember
430 * max_lineno - last line's number, this one doesn't increment
431 * on line wrap, only on "real" new lines.
432 * readbuf[0..readeof-1] - small preliminary buffer.
433 * readbuf[readpos] - next character to add to current line.
434 * last_line_pos - screen line position of next char to be read
435 * (takes into account tabs and backspaces)
436 * eof_error - < 0 error, == 0 EOF, > 0 not EOF/error
438 * "git log -p | less -m" on the kernel git tree is a good test for EAGAINs,
439 * "/search on very long input" and "reaching max line count" corner cases.
441 static void read_lines(void)
443 #define readbuf bb_common_bufsiz1
444 #define sizeof_readbuf COMMON_BUFSIZE
445 char *current_line, *p;
447 char last_terminated = terminated;
448 time_t last_time = 0;
449 int retry_EAGAIN = 2;
450 #if ENABLE_FEATURE_LESS_REGEXP
451 unsigned old_max_fline = max_fline;
454 /* (careful: max_fline can be -1) */
455 if (max_fline + 1 > MAXLINES)
458 if (option_mask32 & FLAG_N)
461 p = current_line = ((char*)xmalloc(w + 5)) + 4;
462 if (!last_terminated) {
463 const char *cp = flines[max_fline];
466 /* last_line_pos is still valid from previous read_lines() */
472 while (1) { /* read lines until we reach cur_fline or wanted_match */
475 while (1) { /* read chars until we have a line */
477 /* if no unprocessed chars left, eat more */
478 if (readpos >= readeof) {
479 int flags = ndelay_on(0);
485 eof_error = safe_read(STDIN_FILENO, readbuf, sizeof_readbuf);
489 if (t != last_time) {
491 if (--retry_EAGAIN < 0)
496 fcntl(0, F_SETFL, flags); /* ndelay_off(0) */
503 c = readbuf[readpos];
504 /* backspace? [needed for manpages] */
505 /* <tab><bs> is (a) insane and */
506 /* (b) harder to do correctly, so we refuse to do it */
507 if (c == '\x8' && last_line_pos && p[-1] != '\t') {
508 readpos++; /* eat it */
510 /* was buggy (p could end up <= current_line)... */
515 size_t new_last_line_pos = last_line_pos + 1;
517 new_last_line_pos += 7;
518 new_last_line_pos &= (~7);
520 if ((int)new_last_line_pos > w)
522 last_line_pos = new_last_line_pos;
524 /* ok, we will eat this char */
531 /* NUL is substituted by '\n'! */
532 if (c == '\0') c = '\n';
535 } /* end of "read chars until we have a line" loop */
537 //BUG: also triggers on this:
538 // { printf "\nfoo\n"; sleep 1; printf "\nbar\n"; } | less
539 // (resulting in lost empty line between "foo" and "bar" lines)
540 // the "terminated" logic needs fixing (or explaining)
541 /* Corner case: linewrap with only "" wrapping to next line */
542 /* Looks ugly on screen, so we do not store this empty line */
543 if (!last_terminated && !current_line[0]) {
550 last_terminated = terminated;
551 flines = xrealloc_vector(flines, 8, max_fline);
553 flines[max_fline] = (char*)xrealloc(MEMPTR(current_line), strlen(current_line) + 1 + 4) + 4;
554 LINENO(flines[max_fline]) = max_lineno;
558 if (max_fline >= MAXLINES) {
559 eof_error = 0; /* Pretend we saw EOF */
563 #if !ENABLE_FEATURE_LESS_REGEXP
566 if (wanted_match >= num_matches) { /* goto_match called us */
567 fill_match_lines(old_max_fline);
568 old_max_fline = max_fline;
570 if (wanted_match < num_matches)
574 if (eof_error <= 0) {
578 current_line = ((char*)xmalloc(w + 5)) + 4;
581 } /* end of "read lines until we reach cur_fline" loop */
584 if (errno == EAGAIN) {
587 print_statusline(bb_msg_read_error);
590 #if ENABLE_FEATURE_LESS_FLAGS
591 else if (eof_error == 0)
592 num_lines = max_lineno;
595 fill_match_lines(old_max_fline);
596 #if ENABLE_FEATURE_LESS_REGEXP
597 /* prevent us from being stuck in search for a match */
603 #if ENABLE_FEATURE_LESS_FLAGS
604 static int safe_lineno(int fline)
606 if (fline >= max_fline)
607 fline = max_fline - 1;
609 /* also catches empty file (max_fline == 0) */
613 return LINENO(flines[fline]) + 1;
616 /* count number of lines in file */
617 static void update_num_lines(void)
624 /* only do this for regular files */
625 if (num_lines == REOPEN_AND_COUNT || num_lines == REOPEN_STDIN) {
627 fd = open("/proc/self/fd/0", O_RDONLY);
628 if (fd < 0 && num_lines == REOPEN_AND_COUNT) {
629 /* "filename" is valid only if REOPEN_AND_COUNT */
630 fd = open(filename, O_RDONLY);
633 /* somebody stole my file! */
634 num_lines = NOT_REGULAR_FILE;
637 if (fstat(fd, &stbuf) != 0 || !S_ISREG(stbuf.st_mode)) {
638 num_lines = NOT_REGULAR_FILE;
641 while ((len = safe_read(fd, buf, sizeof(buf))) > 0) {
642 for (i = 0; i < len; ++i) {
643 if (buf[i] == '\n' && ++count == MAXLINES)
654 /* Print a status line if -M was specified */
655 static void m_status_print(void)
660 if (less_gets_pos >= 0) /* don't touch statusline while input is done! */
664 printf(HIGHLIGHT"%s", filename);
666 printf(" (file %i of %i)", current_file, num_files);
668 first = safe_lineno(cur_fline);
669 last = (option_mask32 & FLAG_S)
670 ? MIN(first + max_displayed_line, max_lineno)
671 : safe_lineno(cur_fline + max_displayed_line);
672 printf(" lines %i-%i", first, last);
676 printf("/%i", num_lines);
680 if (num_files > 1 && current_file != num_files)
681 printf(" - next: %s", files[current_file]);
682 } else if (num_lines > 0) {
683 percent = (100 * last + num_lines/2) / num_lines;
684 printf(" %i%%", percent <= 100 ? percent : 100);
690 /* Print the status line */
691 static void status_print(void)
695 if (less_gets_pos >= 0) /* don't touch statusline while input is done! */
698 /* Change the status if flags have been set */
699 #if ENABLE_FEATURE_LESS_FLAGS
700 if (option_mask32 & (FLAG_M|FLAG_m)) {
708 if (cur_fline && !at_end()) {
716 printf(HIGHLIGHT"%s (file %i of %i)"NORMAL,
717 p, current_file, num_files);
723 static const char controls[] ALIGN1 =
724 /* NUL: never encountered; TAB: not converted */
725 /**/"\x01\x02\x03\x04\x05\x06\x07\x08" "\x0a\x0b\x0c\x0d\x0e\x0f"
726 "\x10\x11\x12\x13\x14\x15\x16\x17\x18\x19\x1a\x1b\x1c\x1d\x1e\x1f"
727 "\x7f\x9b"; /* DEL and infamous Meta-ESC :( */
728 static const char ctrlconv[] ALIGN1 =
729 /* why 40 instead of 4a below? - it is a replacement for '\n'.
730 * '\n' is a former NUL - we subst it with @, not J */
731 "\x40\x41\x42\x43\x44\x45\x46\x47\x48\x49\x40\x4b\x4c\x4d\x4e\x4f"
732 "\x50\x51\x52\x53\x54\x55\x56\x57\x58\x59\x5a\x5b\x5c\x5d\x5e\x5f";
734 static void print_lineno(const char *line)
736 const char *fmt = " ";
737 unsigned n = n; /* for compiler */
739 if (line != empty_line_marker) {
740 /* Width of 7 preserves tab spacing in the text */
742 n = LINENO(line) + 1;
743 if (n > 9999999 && MAXLINES > 9999999) {
752 #if ENABLE_FEATURE_LESS_REGEXP
753 static void print_found(const char *line)
758 regmatch_t match_structs;
761 const char *str = line;
766 n = strcspn(str, controls);
773 n = strspn(str, controls);
780 /* buf[] holds quarantined version of str */
782 /* Each part of the line that matches has the HIGHLIGHT
783 * and NORMAL escape sequences placed around it.
784 * NB: we regex against line, but insert text
785 * from quarantined copy (buf[]) */
791 while (match_status == 0) {
792 char *new = xasprintf("%s%.*s"HIGHLIGHT"%.*s"NORMAL,
793 growline ? growline : "",
794 (int)match_structs.rm_so, str,
795 (int)(match_structs.rm_eo - match_structs.rm_so),
796 str + match_structs.rm_so);
799 str += match_structs.rm_eo;
800 line += match_structs.rm_eo;
803 /* Most of the time doesn't find the regex, optimize for that */
804 match_status = regexec(&pattern, line, 1, &match_structs, eflags);
805 /* if even "" matches, treat it as "not a match" */
806 if (match_structs.rm_so >= match_structs.rm_eo)
810 printf("%s%s\n", growline ? growline : "", str);
814 void print_found(const char *line);
817 static void print_ascii(const char *str)
824 n = strcspn(str, controls);
827 printf("%.*s", (int) n, str);
830 n = strspn(str, controls);
835 else if (*str == (char)0x9b)
836 /* VT100's CSI, aka Meta-ESC. Who's inventor? */
837 /* I want to know who committed this sin */
840 *p++ = ctrlconv[(unsigned char)*str];
849 /* Print the buffer */
850 static void buffer_print(void)
855 for (i = 0; i <= max_displayed_line; i++) {
857 if (option_mask32 & FLAG_N)
858 print_lineno(buffer[i]);
860 print_found(buffer[i]);
862 print_ascii(buffer[i]);
864 if ((option_mask32 & FLAG_E)
866 && (max_fline - cur_fline) <= max_displayed_line
868 less_exit(EXIT_SUCCESS);
873 static void buffer_fill_and_print(void)
876 #if ENABLE_FEATURE_LESS_TRUNCATE
877 int fpos = cur_fline;
879 if (option_mask32 & FLAG_S) {
880 /* Go back to the beginning of this line */
881 while (fpos && LINENO(flines[fpos]) == LINENO(flines[fpos-1]))
886 while (i <= max_displayed_line && fpos <= max_fline) {
887 int lineno = LINENO(flines[fpos]);
888 buffer[i] = flines[fpos];
892 } while ((fpos <= max_fline)
893 && (option_mask32 & FLAG_S)
894 && lineno == LINENO(flines[fpos])
898 for (i = 0; i <= max_displayed_line && cur_fline + i <= max_fline; i++) {
899 buffer[i] = flines[cur_fline + i];
902 for (; i <= max_displayed_line; i++) {
903 buffer[i] = empty_line_marker;
908 /* move cur_fline to a given line number, reading lines if necessary */
909 static void goto_lineno(int target)
914 else if (target > LINENO(flines[cur_fline])) {
916 while (LINENO(flines[cur_fline]) != target && cur_fline < max_fline)
918 /* target not reached but more input is available */
919 if (LINENO(flines[cur_fline]) != target && eof_error > 0) {
925 /* search backwards through already-read lines */
926 while (LINENO(flines[cur_fline]) != target && cur_fline > 0)
931 static void cap_cur_fline(void)
933 if ((option_mask32 & FLAG_S)) {
934 if (cur_fline > max_fline)
935 cur_fline = max_fline;
936 if (LINENO(flines[cur_fline]) + max_displayed_line > max_lineno + TILDES) {
937 goto_lineno(max_lineno - max_displayed_line + TILDES);
942 if (cur_fline + max_displayed_line > max_fline + TILDES)
943 cur_fline = max_fline - max_displayed_line + TILDES;
949 /* Move the buffer up and down in the file in order to scroll */
950 static void buffer_down(int nlines)
952 if ((option_mask32 & FLAG_S))
953 goto_lineno(LINENO(flines[cur_fline]) + nlines);
958 buffer_fill_and_print();
961 static void buffer_up(int nlines)
963 if ((option_mask32 & FLAG_S)) {
964 goto_lineno(LINENO(flines[cur_fline]) - nlines);
972 buffer_fill_and_print();
975 /* display a given line where the argument can be either an index into
976 * the flines array or a line number */
977 static void buffer_to_line(int linenum, int is_lineno)
982 goto_lineno(linenum);
987 buffer_fill_and_print();
990 static void buffer_line(int linenum)
992 buffer_to_line(linenum, FALSE);
995 static void buffer_lineno(int lineno)
997 buffer_to_line(lineno, TRUE);
1000 static void open_file_and_read_lines(void)
1003 xmove_fd(xopen(filename, O_RDONLY), STDIN_FILENO);
1004 #if ENABLE_FEATURE_LESS_FLAGS
1005 num_lines = REOPEN_AND_COUNT;
1008 /* "less" with no arguments in argv[] */
1009 /* For status line only */
1010 filename = xstrdup(bb_msg_standard_input);
1011 #if ENABLE_FEATURE_LESS_FLAGS
1012 num_lines = REOPEN_STDIN;
1022 /* Reinitialize everything for a new file - free the memory and start over */
1023 static void reinitialize(void)
1028 for (i = 0; i <= max_fline; i++)
1029 free(MEMPTR(flines[i]));
1037 open_file_and_read_lines();
1038 #if ENABLE_FEATURE_LESS_ASK_TERMINAL
1040 printf("\033[999;999H" "\033[6n");
1042 buffer_fill_and_print();
1045 static int64_t getch_nowait(void)
1049 struct pollfd pfd[2];
1051 pfd[0].fd = STDIN_FILENO;
1052 pfd[0].events = POLLIN;
1054 pfd[1].events = POLLIN;
1056 tcsetattr(kbd_fd, TCSANOW, &term_less);
1057 /* NB: select/poll returns whenever read will not block. Therefore:
1058 * if eof is reached, select/poll will return immediately
1059 * because read will immediately return 0 bytes.
1060 * Even if select/poll says that input is available, read CAN block
1061 * (switch fd into O_NONBLOCK'ed mode to avoid it)
1064 /* Are we interested in stdin? */
1066 if (eof_error > 0) /* did NOT reach eof yet */
1067 rd = 0; /* yes, we are interested in stdin */
1069 /* Position cursor if line input is done */
1070 if (less_gets_pos >= 0)
1071 move_cursor(max_displayed_line + 2, less_gets_pos + 1);
1074 if (kbd_input[0] == 0) { /* if nothing is buffered */
1075 #if ENABLE_FEATURE_LESS_WINCH
1078 /* NB: SIGWINCH interrupts poll() */
1079 r = poll(pfd + rd, 2 - rd, -1);
1080 if (/*r < 0 && errno == EINTR &&*/ winch_counter)
1081 return '\\'; /* anything which has no defined function */
1085 safe_poll(pfd + rd, 2 - rd, -1);
1089 /* We have kbd_fd in O_NONBLOCK mode, read inside read_key()
1090 * would not block even if there is no input available */
1091 key64 = read_key(kbd_fd, kbd_input, /*timeout off:*/ -2);
1092 if ((int)key64 == -1) {
1093 if (errno == EAGAIN) {
1094 /* No keyboard input available. Since poll() did return,
1095 * we should have input on stdin */
1097 buffer_fill_and_print();
1100 /* EOF/error (ssh session got killed etc) */
1107 /* Grab a character from input without requiring the return key.
1108 * May return KEYCODE_xxx values.
1109 * Note that this function works best with raw input. */
1110 static int64_t less_getch(int pos)
1116 less_gets_pos = pos;
1117 key = key64 = getch_nowait();
1120 /* Discard Ctrl-something chars.
1121 * (checking only lower 32 bits is a size optimization:
1122 * upper 32 bits are used only by KEYCODE_CURSOR_POS)
1124 if (key >= 0 && key < ' ' && key != 0x0d && key != 8)
1130 static char* less_gets(int sz)
1134 char *result = xzalloc(1);
1138 less_gets_pos = sz + i;
1151 if (c < ' ') /* filters out KEYCODE_xxx too (<0) */
1153 if (i >= width - sz - 1)
1154 continue; /* len limit */
1157 result = xrealloc(result, i+1);
1161 static void examine_file(void)
1165 print_statusline("Examine: ");
1166 new_fname = less_gets(sizeof("Examine: ") - 1);
1167 if (!new_fname[0]) {
1173 if (access(new_fname, R_OK) != 0) {
1174 print_statusline("Cannot read this file");
1178 filename = new_fname;
1179 /* files start by = argv. why we assume that argv is infinitely long??
1180 files[num_files] = filename;
1181 current_file = num_files + 1;
1183 files[0] = filename;
1184 num_files = current_file = 1;
1188 /* This function changes the file currently being paged. direction can be one of the following:
1189 * -1: go back one file
1190 * 0: go to the first file
1191 * 1: go forward one file */
1192 static void change_file(int direction)
1194 if (current_file != ((direction > 0) ? num_files : 1)) {
1195 current_file = direction ? current_file + direction : 1;
1197 filename = xstrdup(files[current_file - 1]);
1200 print_statusline(direction > 0 ? "No next file" : "No previous file");
1204 static void remove_current_file(void)
1211 if (current_file != 1) {
1213 for (i = 3; i <= num_files; i++)
1214 files[i - 2] = files[i - 1];
1218 for (i = 2; i <= num_files; i++)
1219 files[i - 2] = files[i - 1];
1225 static void colon_process(void)
1229 /* Clear the current line and print a prompt */
1230 print_statusline(" :");
1232 keypress = less_getch(2);
1235 remove_current_file();
1240 #if ENABLE_FEATURE_LESS_FLAGS
1252 less_exit(EXIT_SUCCESS);
1260 #if ENABLE_FEATURE_LESS_REGEXP
1261 static void normalize_match_pos(int match)
1263 if (match >= num_matches)
1264 match = num_matches - 1;
1270 static void goto_match(int match)
1276 /* Try to find next match if eof isn't reached yet */
1277 if (match >= num_matches && eof_error > 0) {
1278 wanted_match = match; /* "I want to read until I see N'th match" */
1282 normalize_match_pos(match);
1283 buffer_line(match_lines[match_pos]);
1285 print_statusline("No matches found");
1289 static void fill_match_lines(unsigned pos)
1293 /* Run the regex on each line of the current file */
1294 while (pos <= max_fline) {
1295 /* If this line matches */
1296 if (regexec(&pattern, flines[pos], 0, NULL, 0) == 0
1297 /* and we didn't match it last time */
1298 && !(num_matches && match_lines[num_matches-1] == pos)
1300 match_lines = xrealloc_vector(match_lines, 4, num_matches);
1301 match_lines[num_matches++] = pos;
1307 static void regex_process(void)
1309 char *uncomp_regex, *err;
1311 /* Reset variables */
1316 if (pattern_valid) {
1321 /* Get the uncompiled regular expression from the user */
1323 bb_putchar((option_mask32 & LESS_STATE_MATCH_BACKWARDS) ? '?' : '/');
1324 uncomp_regex = less_gets(1);
1325 if (!uncomp_regex[0]) {
1331 /* Compile the regex and check for errors */
1332 err = regcomp_or_errmsg(&pattern, uncomp_regex,
1333 (option_mask32 & FLAG_I) ? REG_ICASE : 0);
1336 print_statusline(err);
1343 fill_match_lines(0);
1344 while (match_pos < num_matches) {
1345 if ((int)match_lines[match_pos] > cur_fline)
1349 if (option_mask32 & LESS_STATE_MATCH_BACKWARDS)
1352 /* It's possible that no matches are found yet.
1353 * goto_match() will read input looking for match,
1355 goto_match(match_pos);
1359 static void number_process(int first_digit)
1364 char num_input[sizeof(int)*4]; /* more than enough */
1366 num_input[0] = first_digit;
1368 /* Clear the current line, print a prompt, and then print the digit */
1370 printf(":%c", first_digit);
1372 /* Receive input until a letter is given */
1374 while (i < sizeof(num_input)-1) {
1375 keypress = less_getch(i + 1);
1376 if ((unsigned)keypress > 255 || !isdigit(keypress))
1378 num_input[i] = keypress;
1379 bb_putchar(keypress);
1383 num_input[i] = '\0';
1384 num = bb_strtou(num_input, NULL, 10);
1385 /* on format error, num == -1 */
1386 if (num < 1 || num > MAXLINES) {
1391 /* We now know the number and the letter entered, so we process them */
1393 case KEYCODE_DOWN: case 'z': case 'd': case 'e': case ' ': case '\015':
1396 case KEYCODE_UP: case 'b': case 'w': case 'y': case 'u':
1399 case 'g': case '<': case 'G': case '>':
1400 buffer_lineno(num - 1);
1403 #if ENABLE_FEATURE_LESS_FLAGS
1405 num = num * (num_lines > 0 ? num_lines : max_lineno) / 100;
1407 num = num * max_lineno / 100;
1411 #if ENABLE_FEATURE_LESS_REGEXP
1413 goto_match(match_pos + num);
1416 option_mask32 &= ~LESS_STATE_MATCH_BACKWARDS;
1420 option_mask32 |= LESS_STATE_MATCH_BACKWARDS;
1427 #if ENABLE_FEATURE_LESS_DASHCMD
1428 static void flag_change(void)
1434 keypress = less_getch(1);
1438 option_mask32 ^= FLAG_M;
1441 option_mask32 ^= FLAG_m;
1444 option_mask32 ^= FLAG_E;
1447 option_mask32 ^= FLAG_TILDE;
1449 #if ENABLE_FEATURE_LESS_TRUNCATE
1451 option_mask32 ^= FLAG_S;
1452 buffer_fill_and_print();
1455 #if ENABLE_FEATURE_LESS_LINENUMS
1457 option_mask32 ^= FLAG_N;
1459 buffer_fill_and_print();
1466 static void show_flag_status(void)
1473 keypress = less_getch(1);
1477 flag_val = option_mask32 & FLAG_M;
1480 flag_val = option_mask32 & FLAG_m;
1483 flag_val = option_mask32 & FLAG_TILDE;
1486 flag_val = option_mask32 & FLAG_N;
1489 flag_val = option_mask32 & FLAG_E;
1497 printf(HIGHLIGHT"The status of the flag is: %u"NORMAL, flag_val != 0);
1501 #endif /* ENABLE_FEATURE_LESS_DASHCMD */
1503 static void save_input_to_file(void)
1505 const char *msg = "";
1510 print_statusline("Log file: ");
1511 current_line = less_gets(sizeof("Log file: ")-1);
1512 if (current_line[0]) {
1513 fp = fopen_for_write(current_line);
1515 msg = "Error opening log file";
1518 for (i = 0; i <= max_fline; i++)
1519 fprintf(fp, "%s\n", flines[i]);
1524 print_statusline(msg);
1528 #if ENABLE_FEATURE_LESS_MARKS
1529 static void add_mark(void)
1533 print_statusline("Mark: ");
1534 letter = less_getch(sizeof("Mark: ") - 1);
1536 if (isalpha(letter)) {
1537 /* If we exceed 15 marks, start overwriting previous ones */
1538 if (num_marks == 14)
1541 mark_lines[num_marks][0] = letter;
1542 mark_lines[num_marks][1] = cur_fline;
1545 print_statusline("Invalid mark letter");
1549 static void goto_mark(void)
1554 print_statusline("Go to mark: ");
1555 letter = less_getch(sizeof("Go to mark: ") - 1);
1558 if (isalpha(letter)) {
1559 for (i = 0; i <= num_marks; i++)
1560 if (letter == mark_lines[i][0]) {
1561 buffer_line(mark_lines[i][1]);
1564 if (num_marks == 14 && letter != mark_lines[14][0])
1565 print_statusline("Mark not set");
1567 print_statusline("Invalid mark letter");
1571 #if ENABLE_FEATURE_LESS_BRACKETS
1572 static char opp_bracket(char bracket)
1575 case '{': case '[': /* '}' == '{' + 2. Same for '[' */
1577 case '(': /* ')' == '(' + 1 */
1589 static void match_right_bracket(char bracket)
1593 if (strchr(flines[cur_fline], bracket) == NULL) {
1594 print_statusline("No bracket in top line");
1597 bracket = opp_bracket(bracket);
1598 for (i = cur_fline + 1; i < max_fline; i++) {
1599 if (strchr(flines[i], bracket) != NULL) {
1604 print_statusline("No matching bracket found");
1607 static void match_left_bracket(char bracket)
1611 if (strchr(flines[cur_fline + max_displayed_line], bracket) == NULL) {
1612 print_statusline("No bracket in bottom line");
1616 bracket = opp_bracket(bracket);
1617 for (i = cur_fline + max_displayed_line; i >= 0; i--) {
1618 if (strchr(flines[i], bracket) != NULL) {
1623 print_statusline("No matching bracket found");
1625 #endif /* FEATURE_LESS_BRACKETS */
1627 static void keypress_process(int keypress)
1630 case KEYCODE_DOWN: case 'e': case 'j': case 0x0d:
1633 case KEYCODE_UP: case 'y': case 'k':
1636 case KEYCODE_PAGEDOWN: case ' ': case 'z': case 'f':
1637 buffer_down(max_displayed_line + 1);
1639 case KEYCODE_PAGEUP: case 'w': case 'b':
1640 buffer_up(max_displayed_line + 1);
1643 buffer_down((max_displayed_line + 1) / 2);
1646 buffer_up((max_displayed_line + 1) / 2);
1648 case KEYCODE_HOME: case 'g': case 'p': case '<': case '%':
1651 case KEYCODE_END: case 'G': case '>':
1652 cur_fline = MAXLINES;
1654 buffer_line(cur_fline);
1657 less_exit(EXIT_SUCCESS);
1659 #if ENABLE_FEATURE_LESS_MARKS
1670 /* TODO: (1) also bind ^R, ^L to this?
1671 * (2) re-measure window size?
1679 save_input_to_file();
1684 #if ENABLE_FEATURE_LESS_FLAGS
1689 #if ENABLE_FEATURE_LESS_REGEXP
1691 option_mask32 &= ~LESS_STATE_MATCH_BACKWARDS;
1695 goto_match(match_pos + 1);
1698 goto_match(match_pos - 1);
1701 option_mask32 |= LESS_STATE_MATCH_BACKWARDS;
1705 #if ENABLE_FEATURE_LESS_DASHCMD
1716 #if ENABLE_FEATURE_LESS_BRACKETS
1717 case '{': case '(': case '[':
1718 match_right_bracket(keypress);
1720 case '}': case ')': case ']':
1721 match_left_bracket(keypress);
1729 if (isdigit(keypress))
1730 number_process(keypress);
1733 static void sig_catcher(int sig)
1738 #if ENABLE_FEATURE_LESS_WINCH
1739 static void sigwinch_handler(int sig UNUSED_PARAM)
1745 int less_main(int argc, char **argv) MAIN_EXTERNALLY_VISIBLE;
1746 int less_main(int argc, char **argv)
1753 /* TODO: -x: do not interpret backspace, -xx: tab also
1754 * -xxx: newline also
1755 * -w N: assume width N (-xxx -w 32: hex viewer of sorts)
1756 * -s: condense many empty lines to one
1757 * (used by some setups for manpage display)
1759 getopt32(argv, "EMmN~I" IF_FEATURE_LESS_TRUNCATE("S") /*ignored:*/"s");
1765 /* Another popular pager, most, detects when stdout
1766 * is not a tty and turns into cat. This makes sense. */
1767 if (!isatty(STDOUT_FILENO))
1768 return bb_cat(argv);
1771 if (isatty(STDIN_FILENO)) {
1772 /* Just "less"? No args and no redirection? */
1773 bb_error_msg("missing filename");
1777 filename = xstrdup(files[0]);
1780 if (option_mask32 & FLAG_TILDE)
1781 empty_line_marker = "";
1783 /* Some versions of less can survive w/o controlling tty,
1784 * try to do the same. This also allows to specify an alternative
1785 * tty via "less 1<>TTY".
1786 * We don't try to use STDOUT_FILENO directly,
1787 * since we want to set this fd to non-blocking mode,
1788 * and not bother with restoring it on exit.
1790 tty_name = xmalloc_ttyname(STDOUT_FILENO);
1792 tty_fd = open(tty_name, O_RDONLY);
1797 /* Try controlling tty */
1799 tty_fd = open(CURRENT_TTY, O_RDONLY);
1801 return bb_cat(argv);
1804 kbd_fd = tty_fd; /* save in a global */
1806 tcgetattr(kbd_fd, &term_orig);
1807 term_less = term_orig;
1808 term_less.c_lflag &= ~(ICANON | ECHO);
1809 term_less.c_iflag &= ~(IXON | ICRNL);
1810 /*term_less.c_oflag &= ~ONLCR;*/
1811 term_less.c_cc[VMIN] = 1;
1812 term_less.c_cc[VTIME] = 0;
1814 IF_FEATURE_LESS_ASK_TERMINAL(G.winsize_err =) get_terminal_width_height(kbd_fd, &width, &max_displayed_line);
1815 /* 20: two tabstops + 4 */
1816 if (width < 20 || max_displayed_line < 3)
1817 return bb_cat(argv);
1818 max_displayed_line -= 2;
1820 /* We want to restore term_orig on exit */
1821 bb_signals(BB_FATAL_SIGS, sig_catcher);
1822 #if ENABLE_FEATURE_LESS_WINCH
1823 signal(SIGWINCH, sigwinch_handler);
1826 buffer = xmalloc((max_displayed_line+1) * sizeof(char *));
1831 #if ENABLE_FEATURE_LESS_WINCH
1832 while (WINCH_COUNTER) {
1835 IF_FEATURE_LESS_ASK_TERMINAL(G.winsize_err =) get_terminal_width_height(kbd_fd, &width, &max_displayed_line);
1836 IF_FEATURE_LESS_ASK_TERMINAL(got_size:)
1837 /* 20: two tabstops + 4 */
1840 if (max_displayed_line < 3)
1841 max_displayed_line = 3;
1842 max_displayed_line -= 2;
1844 buffer = xmalloc((max_displayed_line+1) * sizeof(char *));
1845 /* Avoid re-wrap and/or redraw if we already know
1846 * we need to do it again. These ops are expensive */
1852 buffer_fill_and_print();
1853 /* This took some time. Loop back and check,
1854 * were there another SIGWINCH? */
1856 keypress = less_getch(-1); /* -1: do not position cursor */
1857 # if ENABLE_FEATURE_LESS_ASK_TERMINAL
1858 if ((int32_t)keypress == KEYCODE_CURSOR_POS) {
1859 uint32_t rc = (keypress >> 32);
1860 width = (rc & 0x7fff);
1861 max_displayed_line = ((rc >> 16) & 0x7fff);
1866 keypress = less_getch(-1); /* -1: do not position cursor */
1868 keypress_process(keypress);
1873 Help text of less version 418 is below.
1874 If you are implementing something, keeping
1875 key and/or command line switch compatibility is a good idea:
1878 SUMMARY OF LESS COMMANDS
1880 Commands marked with * may be preceded by a number, N.
1881 Notes in parentheses indicate the behavior if N is given.
1882 h H Display this help.
1884 ---------------------------------------------------------------------------
1886 e ^E j ^N CR * Forward one line (or N lines).
1887 y ^Y k ^K ^P * Backward one line (or N lines).
1888 f ^F ^V SPACE * Forward one window (or N lines).
1889 b ^B ESC-v * Backward one window (or N lines).
1890 z * Forward one window (and set window to N).
1891 w * Backward one window (and set window to N).
1892 ESC-SPACE * Forward one window, but don't stop at end-of-file.
1893 d ^D * Forward one half-window (and set half-window to N).
1894 u ^U * Backward one half-window (and set half-window to N).
1895 ESC-) RightArrow * Left one half screen width (or N positions).
1896 ESC-( LeftArrow * Right one half screen width (or N positions).
1897 F Forward forever; like "tail -f".
1898 r ^R ^L Repaint screen.
1899 R Repaint screen, discarding buffered input.
1900 ---------------------------------------------------
1901 Default "window" is the screen height.
1902 Default "half-window" is half of the screen height.
1903 ---------------------------------------------------------------------------
1905 /pattern * Search forward for (N-th) matching line.
1906 ?pattern * Search backward for (N-th) matching line.
1907 n * Repeat previous search (for N-th occurrence).
1908 N * Repeat previous search in reverse direction.
1909 ESC-n * Repeat previous search, spanning files.
1910 ESC-N * Repeat previous search, reverse dir. & spanning files.
1911 ESC-u Undo (toggle) search highlighting.
1912 ---------------------------------------------------
1913 Search patterns may be modified by one or more of:
1914 ^N or ! Search for NON-matching lines.
1915 ^E or * Search multiple files (pass thru END OF FILE).
1916 ^F or @ Start search at FIRST file (for /) or last file (for ?).
1917 ^K Highlight matches, but don't move (KEEP position).
1918 ^R Don't use REGULAR EXPRESSIONS.
1919 ---------------------------------------------------------------------------
1921 g < ESC-< * Go to first line in file (or line N).
1922 G > ESC-> * Go to last line in file (or line N).
1923 p % * Go to beginning of file (or N percent into file).
1924 t * Go to the (N-th) next tag.
1925 T * Go to the (N-th) previous tag.
1926 { ( [ * Find close bracket } ) ].
1927 } ) ] * Find open bracket { ( [.
1928 ESC-^F <c1> <c2> * Find close bracket <c2>.
1929 ESC-^B <c1> <c2> * Find open bracket <c1>
1930 ---------------------------------------------------
1931 Each "find close bracket" command goes forward to the close bracket
1932 matching the (N-th) open bracket in the top line.
1933 Each "find open bracket" command goes backward to the open bracket
1934 matching the (N-th) close bracket in the bottom line.
1935 m<letter> Mark the current position with <letter>.
1936 '<letter> Go to a previously marked position.
1937 '' Go to the previous position.
1939 ---------------------------------------------------
1940 A mark is any upper-case or lower-case letter.
1941 Certain marks are predefined:
1942 ^ means beginning of the file
1943 $ means end of the file
1944 ---------------------------------------------------------------------------
1946 :e [file] Examine a new file.
1948 :n * Examine the (N-th) next file from the command line.
1949 :p * Examine the (N-th) previous file from the command line.
1950 :x * Examine the first (or N-th) file from the command line.
1951 :d Delete the current file from the command line list.
1952 = ^G :f Print current file name.
1953 ---------------------------------------------------------------------------
1954 MISCELLANEOUS COMMANDS
1955 -<flag> Toggle a command line option [see OPTIONS below].
1956 --<name> Toggle a command line option, by name.
1957 _<flag> Display the setting of a command line option.
1958 __<name> Display the setting of an option, by name.
1959 +cmd Execute the less cmd each time a new file is examined.
1960 !command Execute the shell command with $SHELL.
1961 |Xcommand Pipe file between current pos & mark X to shell command.
1962 v Edit the current file with $VISUAL or $EDITOR.
1963 V Print version number of "less".
1964 ---------------------------------------------------------------------------
1966 Most options may be changed either on the command line,
1967 or from within less by using the - or -- command.
1968 Options may be given in one of two forms: either a single
1969 character preceded by a -, or a name preceded by --.
1971 Display help (from command line).
1972 -a ........ --search-skip-screen
1973 Forward search skips current screen.
1974 -b [N] .... --buffers=[N]
1976 -B ........ --auto-buffers
1977 Don't automatically allocate buffers for pipes.
1978 -c ........ --clear-screen
1979 Repaint by clearing rather than scrolling.
1982 -D [xn.n] . --color=xn.n
1983 Set screen colors. (MS-DOS only)
1984 -e -E .... --quit-at-eof --QUIT-AT-EOF
1985 Quit at end of file.
1987 Force open non-regular files.
1988 -F ........ --quit-if-one-screen
1989 Quit if entire file fits on first screen.
1990 -g ........ --hilite-search
1991 Highlight only last match for searches.
1992 -G ........ --HILITE-SEARCH
1993 Don't highlight any matches for searches.
1994 -h [N] .... --max-back-scroll=[N]
1995 Backward scroll limit.
1996 -i ........ --ignore-case
1997 Ignore case in searches that do not contain uppercase.
1998 -I ........ --IGNORE-CASE
1999 Ignore case in all searches.
2000 -j [N] .... --jump-target=[N]
2001 Screen position of target lines.
2002 -J ........ --status-column
2003 Display a status column at left edge of screen.
2004 -k [file] . --lesskey-file=[file]
2006 -L ........ --no-lessopen
2007 Ignore the LESSOPEN environment variable.
2008 -m -M .... --long-prompt --LONG-PROMPT
2010 -n -N .... --line-numbers --LINE-NUMBERS
2011 Don't use line numbers.
2012 -o [file] . --log-file=[file]
2013 Copy to log file (standard input only).
2014 -O [file] . --LOG-FILE=[file]
2015 Copy to log file (unconditionally overwrite).
2016 -p [pattern] --pattern=[pattern]
2017 Start at pattern (from command line).
2018 -P [prompt] --prompt=[prompt]
2020 -q -Q .... --quiet --QUIET --silent --SILENT
2021 Quiet the terminal bell.
2022 -r -R .... --raw-control-chars --RAW-CONTROL-CHARS
2023 Output "raw" control characters.
2024 -s ........ --squeeze-blank-lines
2025 Squeeze multiple blank lines.
2026 -S ........ --chop-long-lines
2028 -t [tag] .. --tag=[tag]
2030 -T [tagsfile] --tag-file=[tagsfile]
2031 Use an alternate tags file.
2032 -u -U .... --underline-special --UNDERLINE-SPECIAL
2033 Change handling of backspaces.
2034 -V ........ --version
2035 Display the version number of "less".
2036 -w ........ --hilite-unread
2037 Highlight first new line after forward-screen.
2038 -W ........ --HILITE-UNREAD
2039 Highlight first new line after any forward movement.
2040 -x [N[,...]] --tabs=[N[,...]]
2042 -X ........ --no-init
2043 Don't use termcap init/deinit strings.
2045 Don't use termcap keypad init/deinit strings.
2046 -y [N] .... --max-forw-scroll=[N]
2047 Forward scroll limit.
2048 -z [N] .... --window=[N]
2050 -" [c[c]] . --quotes=[c[c]]
2051 Set shell quote characters.
2053 Don't display tildes after end of file.
2054 -# [N] .... --shift=[N]
2055 Horizontal scroll amount (0 = one half screen width)
2057 ---------------------------------------------------------------------------
2059 These keys can be used to edit text being entered
2060 on the "command line" at the bottom of the screen.
2061 RightArrow ESC-l Move cursor right one character.
2062 LeftArrow ESC-h Move cursor left one character.
2063 CNTL-RightArrow ESC-RightArrow ESC-w Move cursor right one word.
2064 CNTL-LeftArrow ESC-LeftArrow ESC-b Move cursor left one word.
2065 HOME ESC-0 Move cursor to start of line.
2066 END ESC-$ Move cursor to end of line.
2067 BACKSPACE Delete char to left of cursor.
2068 DELETE ESC-x Delete char under cursor.
2069 CNTL-BACKSPACE ESC-BACKSPACE Delete word to left of cursor.
2070 CNTL-DELETE ESC-DELETE ESC-X Delete word under cursor.
2071 CNTL-U ESC (MS-DOS only) Delete entire line.
2072 UpArrow ESC-k Retrieve previous command line.
2073 DownArrow ESC-j Retrieve next command line.
2074 TAB Complete filename & cycle.
2075 SHIFT-TAB ESC-TAB Complete filename & reverse cycle.
2076 CNTL-L Complete filename, list all.