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 char *current_line, *p;
445 char last_terminated = terminated;
446 time_t last_time = 0;
447 int retry_EAGAIN = 2;
448 #if ENABLE_FEATURE_LESS_REGEXP
449 unsigned old_max_fline = max_fline;
452 #define readbuf bb_common_bufsiz1
453 setup_common_bufsiz();
455 /* (careful: max_fline can be -1) */
456 if (max_fline + 1 > MAXLINES)
459 if (option_mask32 & FLAG_N)
462 p = current_line = ((char*)xmalloc(w + 5)) + 4;
463 if (!last_terminated) {
464 const char *cp = flines[max_fline];
467 /* last_line_pos is still valid from previous read_lines() */
473 while (1) { /* read lines until we reach cur_fline or wanted_match */
476 while (1) { /* read chars until we have a line */
478 /* if no unprocessed chars left, eat more */
479 if (readpos >= readeof) {
480 int flags = ndelay_on(0);
486 eof_error = safe_read(STDIN_FILENO, readbuf, COMMON_BUFSIZE);
490 if (t != last_time) {
492 if (--retry_EAGAIN < 0)
497 fcntl(0, F_SETFL, flags); /* ndelay_off(0) */
504 c = readbuf[readpos];
505 /* backspace? [needed for manpages] */
506 /* <tab><bs> is (a) insane and */
507 /* (b) harder to do correctly, so we refuse to do it */
508 if (c == '\x8' && last_line_pos && p[-1] != '\t') {
509 readpos++; /* eat it */
511 /* was buggy (p could end up <= current_line)... */
516 size_t new_last_line_pos = last_line_pos + 1;
518 new_last_line_pos += 7;
519 new_last_line_pos &= (~7);
521 if ((int)new_last_line_pos > w)
523 last_line_pos = new_last_line_pos;
525 /* ok, we will eat this char */
532 /* NUL is substituted by '\n'! */
533 if (c == '\0') c = '\n';
536 } /* end of "read chars until we have a line" loop */
538 //BUG: also triggers on this:
539 // { printf "\nfoo\n"; sleep 1; printf "\nbar\n"; } | less
540 // (resulting in lost empty line between "foo" and "bar" lines)
541 // the "terminated" logic needs fixing (or explaining)
542 /* Corner case: linewrap with only "" wrapping to next line */
543 /* Looks ugly on screen, so we do not store this empty line */
544 if (!last_terminated && !current_line[0]) {
551 last_terminated = terminated;
552 flines = xrealloc_vector(flines, 8, max_fline);
554 flines[max_fline] = (char*)xrealloc(MEMPTR(current_line), strlen(current_line) + 1 + 4) + 4;
555 LINENO(flines[max_fline]) = max_lineno;
559 if (max_fline >= MAXLINES) {
560 eof_error = 0; /* Pretend we saw EOF */
564 #if !ENABLE_FEATURE_LESS_REGEXP
567 if (wanted_match >= num_matches) { /* goto_match called us */
568 fill_match_lines(old_max_fline);
569 old_max_fline = max_fline;
571 if (wanted_match < num_matches)
575 if (eof_error <= 0) {
579 current_line = ((char*)xmalloc(w + 5)) + 4;
582 } /* end of "read lines until we reach cur_fline" loop */
585 if (errno == EAGAIN) {
588 print_statusline(bb_msg_read_error);
591 #if ENABLE_FEATURE_LESS_FLAGS
592 else if (eof_error == 0)
593 num_lines = max_lineno;
596 fill_match_lines(old_max_fline);
597 #if ENABLE_FEATURE_LESS_REGEXP
598 /* prevent us from being stuck in search for a match */
604 #if ENABLE_FEATURE_LESS_FLAGS
605 static int safe_lineno(int fline)
607 if (fline >= max_fline)
608 fline = max_fline - 1;
610 /* also catches empty file (max_fline == 0) */
614 return LINENO(flines[fline]) + 1;
617 /* count number of lines in file */
618 static void update_num_lines(void)
625 /* only do this for regular files */
626 if (num_lines == REOPEN_AND_COUNT || num_lines == REOPEN_STDIN) {
628 fd = open("/proc/self/fd/0", O_RDONLY);
629 if (fd < 0 && num_lines == REOPEN_AND_COUNT) {
630 /* "filename" is valid only if REOPEN_AND_COUNT */
631 fd = open(filename, O_RDONLY);
634 /* somebody stole my file! */
635 num_lines = NOT_REGULAR_FILE;
638 if (fstat(fd, &stbuf) != 0 || !S_ISREG(stbuf.st_mode)) {
639 num_lines = NOT_REGULAR_FILE;
642 while ((len = safe_read(fd, buf, sizeof(buf))) > 0) {
643 for (i = 0; i < len; ++i) {
644 if (buf[i] == '\n' && ++count == MAXLINES)
655 /* Print a status line if -M was specified */
656 static void m_status_print(void)
661 if (less_gets_pos >= 0) /* don't touch statusline while input is done! */
665 printf(HIGHLIGHT"%s", filename);
667 printf(" (file %i of %i)", current_file, num_files);
669 first = safe_lineno(cur_fline);
670 last = (option_mask32 & FLAG_S)
671 ? MIN(first + max_displayed_line, max_lineno)
672 : safe_lineno(cur_fline + max_displayed_line);
673 printf(" lines %i-%i", first, last);
677 printf("/%i", num_lines);
681 if (num_files > 1 && current_file != num_files)
682 printf(" - next: %s", files[current_file]);
683 } else if (num_lines > 0) {
684 percent = (100 * last + num_lines/2) / num_lines;
685 printf(" %i%%", percent <= 100 ? percent : 100);
691 /* Print the status line */
692 static void status_print(void)
696 if (less_gets_pos >= 0) /* don't touch statusline while input is done! */
699 /* Change the status if flags have been set */
700 #if ENABLE_FEATURE_LESS_FLAGS
701 if (option_mask32 & (FLAG_M|FLAG_m)) {
709 if (cur_fline && !at_end()) {
717 printf(HIGHLIGHT"%s (file %i of %i)"NORMAL,
718 p, current_file, num_files);
724 static const char controls[] ALIGN1 =
725 /* NUL: never encountered; TAB: not converted */
726 /**/"\x01\x02\x03\x04\x05\x06\x07\x08" "\x0a\x0b\x0c\x0d\x0e\x0f"
727 "\x10\x11\x12\x13\x14\x15\x16\x17\x18\x19\x1a\x1b\x1c\x1d\x1e\x1f"
728 "\x7f\x9b"; /* DEL and infamous Meta-ESC :( */
729 static const char ctrlconv[] ALIGN1 =
730 /* why 40 instead of 4a below? - it is a replacement for '\n'.
731 * '\n' is a former NUL - we subst it with @, not J */
732 "\x40\x41\x42\x43\x44\x45\x46\x47\x48\x49\x40\x4b\x4c\x4d\x4e\x4f"
733 "\x50\x51\x52\x53\x54\x55\x56\x57\x58\x59\x5a\x5b\x5c\x5d\x5e\x5f";
735 static void print_lineno(const char *line)
737 const char *fmt = " ";
738 unsigned n = n; /* for compiler */
740 if (line != empty_line_marker) {
741 /* Width of 7 preserves tab spacing in the text */
743 n = LINENO(line) + 1;
744 if (n > 9999999 && MAXLINES > 9999999) {
753 #if ENABLE_FEATURE_LESS_REGEXP
754 static void print_found(const char *line)
759 regmatch_t match_structs;
762 const char *str = line;
767 n = strcspn(str, controls);
774 n = strspn(str, controls);
781 /* buf[] holds quarantined version of str */
783 /* Each part of the line that matches has the HIGHLIGHT
784 * and NORMAL escape sequences placed around it.
785 * NB: we regex against line, but insert text
786 * from quarantined copy (buf[]) */
792 while (match_status == 0) {
793 char *new = xasprintf("%s%.*s"HIGHLIGHT"%.*s"NORMAL,
794 growline ? growline : "",
795 (int)match_structs.rm_so, str,
796 (int)(match_structs.rm_eo - match_structs.rm_so),
797 str + match_structs.rm_so);
800 str += match_structs.rm_eo;
801 line += match_structs.rm_eo;
804 /* Most of the time doesn't find the regex, optimize for that */
805 match_status = regexec(&pattern, line, 1, &match_structs, eflags);
806 /* if even "" matches, treat it as "not a match" */
807 if (match_structs.rm_so >= match_structs.rm_eo)
811 printf("%s%s\n", growline ? growline : "", str);
815 void print_found(const char *line);
818 static void print_ascii(const char *str)
825 n = strcspn(str, controls);
828 printf("%.*s", (int) n, str);
831 n = strspn(str, controls);
836 else if (*str == (char)0x9b)
837 /* VT100's CSI, aka Meta-ESC. Who's inventor? */
838 /* I want to know who committed this sin */
841 *p++ = ctrlconv[(unsigned char)*str];
850 /* Print the buffer */
851 static void buffer_print(void)
856 for (i = 0; i <= max_displayed_line; i++) {
858 if (option_mask32 & FLAG_N)
859 print_lineno(buffer[i]);
861 print_found(buffer[i]);
863 print_ascii(buffer[i]);
865 if ((option_mask32 & FLAG_E)
867 && (max_fline - cur_fline) <= max_displayed_line
869 less_exit(EXIT_SUCCESS);
874 static void buffer_fill_and_print(void)
877 #if ENABLE_FEATURE_LESS_TRUNCATE
878 int fpos = cur_fline;
880 if (option_mask32 & FLAG_S) {
881 /* Go back to the beginning of this line */
882 while (fpos && LINENO(flines[fpos]) == LINENO(flines[fpos-1]))
887 while (i <= max_displayed_line && fpos <= max_fline) {
888 int lineno = LINENO(flines[fpos]);
889 buffer[i] = flines[fpos];
893 } while ((fpos <= max_fline)
894 && (option_mask32 & FLAG_S)
895 && lineno == LINENO(flines[fpos])
899 for (i = 0; i <= max_displayed_line && cur_fline + i <= max_fline; i++) {
900 buffer[i] = flines[cur_fline + i];
903 for (; i <= max_displayed_line; i++) {
904 buffer[i] = empty_line_marker;
909 /* move cur_fline to a given line number, reading lines if necessary */
910 static void goto_lineno(int target)
915 else if (target > LINENO(flines[cur_fline])) {
917 while (LINENO(flines[cur_fline]) != target && cur_fline < max_fline)
919 /* target not reached but more input is available */
920 if (LINENO(flines[cur_fline]) != target && eof_error > 0) {
926 /* search backwards through already-read lines */
927 while (LINENO(flines[cur_fline]) != target && cur_fline > 0)
932 static void cap_cur_fline(void)
934 if ((option_mask32 & FLAG_S)) {
935 if (cur_fline > max_fline)
936 cur_fline = max_fline;
937 if (LINENO(flines[cur_fline]) + max_displayed_line > max_lineno + TILDES) {
938 goto_lineno(max_lineno - max_displayed_line + TILDES);
943 if (cur_fline + max_displayed_line > max_fline + TILDES)
944 cur_fline = max_fline - max_displayed_line + TILDES;
950 /* Move the buffer up and down in the file in order to scroll */
951 static void buffer_down(int nlines)
953 if ((option_mask32 & FLAG_S))
954 goto_lineno(LINENO(flines[cur_fline]) + nlines);
959 buffer_fill_and_print();
962 static void buffer_up(int nlines)
964 if ((option_mask32 & FLAG_S)) {
965 goto_lineno(LINENO(flines[cur_fline]) - nlines);
973 buffer_fill_and_print();
976 /* display a given line where the argument can be either an index into
977 * the flines array or a line number */
978 static void buffer_to_line(int linenum, int is_lineno)
983 goto_lineno(linenum);
988 buffer_fill_and_print();
991 static void buffer_line(int linenum)
993 buffer_to_line(linenum, FALSE);
996 static void buffer_lineno(int lineno)
998 buffer_to_line(lineno, TRUE);
1001 static void open_file_and_read_lines(void)
1004 xmove_fd(xopen(filename, O_RDONLY), STDIN_FILENO);
1005 #if ENABLE_FEATURE_LESS_FLAGS
1006 num_lines = REOPEN_AND_COUNT;
1009 /* "less" with no arguments in argv[] */
1010 /* For status line only */
1011 filename = xstrdup(bb_msg_standard_input);
1012 #if ENABLE_FEATURE_LESS_FLAGS
1013 num_lines = REOPEN_STDIN;
1023 /* Reinitialize everything for a new file - free the memory and start over */
1024 static void reinitialize(void)
1029 for (i = 0; i <= max_fline; i++)
1030 free(MEMPTR(flines[i]));
1038 open_file_and_read_lines();
1039 #if ENABLE_FEATURE_LESS_ASK_TERMINAL
1041 printf("\033[999;999H" "\033[6n");
1043 buffer_fill_and_print();
1046 static int64_t getch_nowait(void)
1050 struct pollfd pfd[2];
1052 pfd[0].fd = STDIN_FILENO;
1053 pfd[0].events = POLLIN;
1055 pfd[1].events = POLLIN;
1057 tcsetattr(kbd_fd, TCSANOW, &term_less);
1058 /* NB: select/poll returns whenever read will not block. Therefore:
1059 * if eof is reached, select/poll will return immediately
1060 * because read will immediately return 0 bytes.
1061 * Even if select/poll says that input is available, read CAN block
1062 * (switch fd into O_NONBLOCK'ed mode to avoid it)
1065 /* Are we interested in stdin? */
1067 if (eof_error > 0) /* did NOT reach eof yet */
1068 rd = 0; /* yes, we are interested in stdin */
1070 /* Position cursor if line input is done */
1071 if (less_gets_pos >= 0)
1072 move_cursor(max_displayed_line + 2, less_gets_pos + 1);
1075 if (kbd_input[0] == 0) { /* if nothing is buffered */
1076 #if ENABLE_FEATURE_LESS_WINCH
1079 /* NB: SIGWINCH interrupts poll() */
1080 r = poll(pfd + rd, 2 - rd, -1);
1081 if (/*r < 0 && errno == EINTR &&*/ winch_counter)
1082 return '\\'; /* anything which has no defined function */
1086 safe_poll(pfd + rd, 2 - rd, -1);
1090 /* We have kbd_fd in O_NONBLOCK mode, read inside read_key()
1091 * would not block even if there is no input available */
1092 key64 = read_key(kbd_fd, kbd_input, /*timeout off:*/ -2);
1093 if ((int)key64 == -1) {
1094 if (errno == EAGAIN) {
1095 /* No keyboard input available. Since poll() did return,
1096 * we should have input on stdin */
1098 buffer_fill_and_print();
1101 /* EOF/error (ssh session got killed etc) */
1108 /* Grab a character from input without requiring the return key.
1109 * May return KEYCODE_xxx values.
1110 * Note that this function works best with raw input. */
1111 static int64_t less_getch(int pos)
1117 less_gets_pos = pos;
1118 key = key64 = getch_nowait();
1121 /* Discard Ctrl-something chars.
1122 * (checking only lower 32 bits is a size optimization:
1123 * upper 32 bits are used only by KEYCODE_CURSOR_POS)
1125 if (key >= 0 && key < ' ' && key != 0x0d && key != 8)
1131 static char* less_gets(int sz)
1135 char *result = xzalloc(1);
1139 less_gets_pos = sz + i;
1152 if (c < ' ') /* filters out KEYCODE_xxx too (<0) */
1154 if (i >= width - sz - 1)
1155 continue; /* len limit */
1158 result = xrealloc(result, i+1);
1162 static void examine_file(void)
1166 print_statusline("Examine: ");
1167 new_fname = less_gets(sizeof("Examine: ") - 1);
1168 if (!new_fname[0]) {
1174 if (access(new_fname, R_OK) != 0) {
1175 print_statusline("Cannot read this file");
1179 filename = new_fname;
1180 /* files start by = argv. why we assume that argv is infinitely long??
1181 files[num_files] = filename;
1182 current_file = num_files + 1;
1184 files[0] = filename;
1185 num_files = current_file = 1;
1189 /* This function changes the file currently being paged. direction can be one of the following:
1190 * -1: go back one file
1191 * 0: go to the first file
1192 * 1: go forward one file */
1193 static void change_file(int direction)
1195 if (current_file != ((direction > 0) ? num_files : 1)) {
1196 current_file = direction ? current_file + direction : 1;
1198 filename = xstrdup(files[current_file - 1]);
1201 print_statusline(direction > 0 ? "No next file" : "No previous file");
1205 static void remove_current_file(void)
1212 if (current_file != 1) {
1214 for (i = 3; i <= num_files; i++)
1215 files[i - 2] = files[i - 1];
1219 for (i = 2; i <= num_files; i++)
1220 files[i - 2] = files[i - 1];
1226 static void colon_process(void)
1230 /* Clear the current line and print a prompt */
1231 print_statusline(" :");
1233 keypress = less_getch(2);
1236 remove_current_file();
1241 #if ENABLE_FEATURE_LESS_FLAGS
1253 less_exit(EXIT_SUCCESS);
1261 #if ENABLE_FEATURE_LESS_REGEXP
1262 static void normalize_match_pos(int match)
1264 if (match >= num_matches)
1265 match = num_matches - 1;
1271 static void goto_match(int match)
1277 /* Try to find next match if eof isn't reached yet */
1278 if (match >= num_matches && eof_error > 0) {
1279 wanted_match = match; /* "I want to read until I see N'th match" */
1283 normalize_match_pos(match);
1284 buffer_line(match_lines[match_pos]);
1286 print_statusline("No matches found");
1290 static void fill_match_lines(unsigned pos)
1294 /* Run the regex on each line of the current file */
1295 while (pos <= max_fline) {
1296 /* If this line matches */
1297 if (regexec(&pattern, flines[pos], 0, NULL, 0) == 0
1298 /* and we didn't match it last time */
1299 && !(num_matches && match_lines[num_matches-1] == pos)
1301 match_lines = xrealloc_vector(match_lines, 4, num_matches);
1302 match_lines[num_matches++] = pos;
1308 static void regex_process(void)
1310 char *uncomp_regex, *err;
1312 /* Reset variables */
1317 if (pattern_valid) {
1322 /* Get the uncompiled regular expression from the user */
1324 bb_putchar((option_mask32 & LESS_STATE_MATCH_BACKWARDS) ? '?' : '/');
1325 uncomp_regex = less_gets(1);
1326 if (!uncomp_regex[0]) {
1332 /* Compile the regex and check for errors */
1333 err = regcomp_or_errmsg(&pattern, uncomp_regex,
1334 (option_mask32 & FLAG_I) ? REG_ICASE : 0);
1337 print_statusline(err);
1344 fill_match_lines(0);
1345 while (match_pos < num_matches) {
1346 if ((int)match_lines[match_pos] > cur_fline)
1350 if (option_mask32 & LESS_STATE_MATCH_BACKWARDS)
1353 /* It's possible that no matches are found yet.
1354 * goto_match() will read input looking for match,
1356 goto_match(match_pos);
1360 static void number_process(int first_digit)
1365 char num_input[sizeof(int)*4]; /* more than enough */
1367 num_input[0] = first_digit;
1369 /* Clear the current line, print a prompt, and then print the digit */
1371 printf(":%c", first_digit);
1373 /* Receive input until a letter is given */
1375 while (i < sizeof(num_input)-1) {
1376 keypress = less_getch(i + 1);
1377 if ((unsigned)keypress > 255 || !isdigit(keypress))
1379 num_input[i] = keypress;
1380 bb_putchar(keypress);
1384 num_input[i] = '\0';
1385 num = bb_strtou(num_input, NULL, 10);
1386 /* on format error, num == -1 */
1387 if (num < 1 || num > MAXLINES) {
1392 /* We now know the number and the letter entered, so we process them */
1394 case KEYCODE_DOWN: case 'z': case 'd': case 'e': case ' ': case '\015':
1397 case KEYCODE_UP: case 'b': case 'w': case 'y': case 'u':
1400 case 'g': case '<': case 'G': case '>':
1401 buffer_lineno(num - 1);
1404 #if ENABLE_FEATURE_LESS_FLAGS
1406 num = num * (num_lines > 0 ? num_lines : max_lineno) / 100;
1408 num = num * max_lineno / 100;
1412 #if ENABLE_FEATURE_LESS_REGEXP
1414 goto_match(match_pos + num);
1417 option_mask32 &= ~LESS_STATE_MATCH_BACKWARDS;
1421 option_mask32 |= LESS_STATE_MATCH_BACKWARDS;
1428 #if ENABLE_FEATURE_LESS_DASHCMD
1429 static void flag_change(void)
1435 keypress = less_getch(1);
1439 option_mask32 ^= FLAG_M;
1442 option_mask32 ^= FLAG_m;
1445 option_mask32 ^= FLAG_E;
1448 option_mask32 ^= FLAG_TILDE;
1450 #if ENABLE_FEATURE_LESS_TRUNCATE
1452 option_mask32 ^= FLAG_S;
1453 buffer_fill_and_print();
1456 #if ENABLE_FEATURE_LESS_LINENUMS
1458 option_mask32 ^= FLAG_N;
1460 buffer_fill_and_print();
1467 static void show_flag_status(void)
1474 keypress = less_getch(1);
1478 flag_val = option_mask32 & FLAG_M;
1481 flag_val = option_mask32 & FLAG_m;
1484 flag_val = option_mask32 & FLAG_TILDE;
1487 flag_val = option_mask32 & FLAG_N;
1490 flag_val = option_mask32 & FLAG_E;
1498 printf(HIGHLIGHT"The status of the flag is: %u"NORMAL, flag_val != 0);
1502 #endif /* ENABLE_FEATURE_LESS_DASHCMD */
1504 static void save_input_to_file(void)
1506 const char *msg = "";
1511 print_statusline("Log file: ");
1512 current_line = less_gets(sizeof("Log file: ")-1);
1513 if (current_line[0]) {
1514 fp = fopen_for_write(current_line);
1516 msg = "Error opening log file";
1519 for (i = 0; i <= max_fline; i++)
1520 fprintf(fp, "%s\n", flines[i]);
1525 print_statusline(msg);
1529 #if ENABLE_FEATURE_LESS_MARKS
1530 static void add_mark(void)
1534 print_statusline("Mark: ");
1535 letter = less_getch(sizeof("Mark: ") - 1);
1537 if (isalpha(letter)) {
1538 /* If we exceed 15 marks, start overwriting previous ones */
1539 if (num_marks == 14)
1542 mark_lines[num_marks][0] = letter;
1543 mark_lines[num_marks][1] = cur_fline;
1546 print_statusline("Invalid mark letter");
1550 static void goto_mark(void)
1555 print_statusline("Go to mark: ");
1556 letter = less_getch(sizeof("Go to mark: ") - 1);
1559 if (isalpha(letter)) {
1560 for (i = 0; i <= num_marks; i++)
1561 if (letter == mark_lines[i][0]) {
1562 buffer_line(mark_lines[i][1]);
1565 if (num_marks == 14 && letter != mark_lines[14][0])
1566 print_statusline("Mark not set");
1568 print_statusline("Invalid mark letter");
1572 #if ENABLE_FEATURE_LESS_BRACKETS
1573 static char opp_bracket(char bracket)
1576 case '{': case '[': /* '}' == '{' + 2. Same for '[' */
1578 case '(': /* ')' == '(' + 1 */
1590 static void match_right_bracket(char bracket)
1592 unsigned i = cur_fline;
1595 || strchr(flines[i], bracket) == NULL
1597 print_statusline("No bracket in top line");
1601 bracket = opp_bracket(bracket);
1602 for (; i < max_fline; i++) {
1603 if (strchr(flines[i], bracket) != NULL) {
1605 * Line with matched right bracket becomes
1608 buffer_line(i - max_displayed_line);
1612 print_statusline("No matching bracket found");
1615 static void match_left_bracket(char bracket)
1617 int i = cur_fline + max_displayed_line;
1620 || strchr(flines[i], bracket) == NULL
1622 print_statusline("No bracket in bottom line");
1626 bracket = opp_bracket(bracket);
1627 for (; i >= 0; i--) {
1628 if (strchr(flines[i], bracket) != NULL) {
1630 * Line with matched left bracket becomes
1631 * first visible line
1637 print_statusline("No matching bracket found");
1639 #endif /* FEATURE_LESS_BRACKETS */
1641 static void keypress_process(int keypress)
1644 case KEYCODE_DOWN: case 'e': case 'j': case 0x0d:
1647 case KEYCODE_UP: case 'y': case 'k':
1650 case KEYCODE_PAGEDOWN: case ' ': case 'z': case 'f':
1651 buffer_down(max_displayed_line + 1);
1653 case KEYCODE_PAGEUP: case 'w': case 'b':
1654 buffer_up(max_displayed_line + 1);
1657 buffer_down((max_displayed_line + 1) / 2);
1660 buffer_up((max_displayed_line + 1) / 2);
1662 case KEYCODE_HOME: case 'g': case 'p': case '<': case '%':
1665 case KEYCODE_END: case 'G': case '>':
1666 cur_fline = MAXLINES;
1668 buffer_line(cur_fline);
1671 less_exit(EXIT_SUCCESS);
1673 #if ENABLE_FEATURE_LESS_MARKS
1684 /* TODO: (1) also bind ^R, ^L to this?
1685 * (2) re-measure window size?
1693 save_input_to_file();
1698 #if ENABLE_FEATURE_LESS_FLAGS
1703 #if ENABLE_FEATURE_LESS_REGEXP
1705 option_mask32 &= ~LESS_STATE_MATCH_BACKWARDS;
1709 goto_match(match_pos + 1);
1712 goto_match(match_pos - 1);
1715 option_mask32 |= LESS_STATE_MATCH_BACKWARDS;
1719 #if ENABLE_FEATURE_LESS_DASHCMD
1730 #if ENABLE_FEATURE_LESS_BRACKETS
1731 case '{': case '(': case '[':
1732 match_right_bracket(keypress);
1734 case '}': case ')': case ']':
1735 match_left_bracket(keypress);
1743 if (isdigit(keypress))
1744 number_process(keypress);
1747 static void sig_catcher(int sig)
1752 #if ENABLE_FEATURE_LESS_WINCH
1753 static void sigwinch_handler(int sig UNUSED_PARAM)
1759 int less_main(int argc, char **argv) MAIN_EXTERNALLY_VISIBLE;
1760 int less_main(int argc, char **argv)
1767 /* TODO: -x: do not interpret backspace, -xx: tab also
1768 * -xxx: newline also
1769 * -w N: assume width N (-xxx -w 32: hex viewer of sorts)
1770 * -s: condense many empty lines to one
1771 * (used by some setups for manpage display)
1773 getopt32(argv, "EMmN~I" IF_FEATURE_LESS_TRUNCATE("S") /*ignored:*/"s");
1779 /* Another popular pager, most, detects when stdout
1780 * is not a tty and turns into cat. This makes sense. */
1781 if (!isatty(STDOUT_FILENO))
1782 return bb_cat(argv);
1785 if (isatty(STDIN_FILENO)) {
1786 /* Just "less"? No args and no redirection? */
1787 bb_error_msg("missing filename");
1791 filename = xstrdup(files[0]);
1794 if (option_mask32 & FLAG_TILDE)
1795 empty_line_marker = "";
1797 /* Some versions of less can survive w/o controlling tty,
1798 * try to do the same. This also allows to specify an alternative
1799 * tty via "less 1<>TTY".
1800 * We don't try to use STDOUT_FILENO directly,
1801 * since we want to set this fd to non-blocking mode,
1802 * and not bother with restoring it on exit.
1804 tty_name = xmalloc_ttyname(STDOUT_FILENO);
1806 tty_fd = open(tty_name, O_RDONLY);
1811 /* Try controlling tty */
1813 tty_fd = open(CURRENT_TTY, O_RDONLY);
1815 return bb_cat(argv);
1818 kbd_fd = tty_fd; /* save in a global */
1820 tcgetattr(kbd_fd, &term_orig);
1821 term_less = term_orig;
1822 term_less.c_lflag &= ~(ICANON | ECHO);
1823 term_less.c_iflag &= ~(IXON | ICRNL);
1824 /*term_less.c_oflag &= ~ONLCR;*/
1825 term_less.c_cc[VMIN] = 1;
1826 term_less.c_cc[VTIME] = 0;
1828 IF_FEATURE_LESS_ASK_TERMINAL(G.winsize_err =) get_terminal_width_height(kbd_fd, &width, &max_displayed_line);
1829 /* 20: two tabstops + 4 */
1830 if (width < 20 || max_displayed_line < 3)
1831 return bb_cat(argv);
1832 max_displayed_line -= 2;
1834 /* We want to restore term_orig on exit */
1835 bb_signals(BB_FATAL_SIGS, sig_catcher);
1836 #if ENABLE_FEATURE_LESS_WINCH
1837 signal(SIGWINCH, sigwinch_handler);
1840 buffer = xmalloc((max_displayed_line+1) * sizeof(char *));
1845 #if ENABLE_FEATURE_LESS_WINCH
1846 while (WINCH_COUNTER) {
1849 IF_FEATURE_LESS_ASK_TERMINAL(G.winsize_err =) get_terminal_width_height(kbd_fd, &width, &max_displayed_line);
1850 IF_FEATURE_LESS_ASK_TERMINAL(got_size:)
1851 /* 20: two tabstops + 4 */
1854 if (max_displayed_line < 3)
1855 max_displayed_line = 3;
1856 max_displayed_line -= 2;
1858 buffer = xmalloc((max_displayed_line+1) * sizeof(char *));
1859 /* Avoid re-wrap and/or redraw if we already know
1860 * we need to do it again. These ops are expensive */
1866 buffer_fill_and_print();
1867 /* This took some time. Loop back and check,
1868 * were there another SIGWINCH? */
1870 keypress = less_getch(-1); /* -1: do not position cursor */
1871 # if ENABLE_FEATURE_LESS_ASK_TERMINAL
1872 if ((int32_t)keypress == KEYCODE_CURSOR_POS) {
1873 uint32_t rc = (keypress >> 32);
1874 width = (rc & 0x7fff);
1875 max_displayed_line = ((rc >> 16) & 0x7fff);
1880 keypress = less_getch(-1); /* -1: do not position cursor */
1882 keypress_process(keypress);
1887 Help text of less version 418 is below.
1888 If you are implementing something, keeping
1889 key and/or command line switch compatibility is a good idea:
1892 SUMMARY OF LESS COMMANDS
1894 Commands marked with * may be preceded by a number, N.
1895 Notes in parentheses indicate the behavior if N is given.
1896 h H Display this help.
1898 ---------------------------------------------------------------------------
1900 e ^E j ^N CR * Forward one line (or N lines).
1901 y ^Y k ^K ^P * Backward one line (or N lines).
1902 f ^F ^V SPACE * Forward one window (or N lines).
1903 b ^B ESC-v * Backward one window (or N lines).
1904 z * Forward one window (and set window to N).
1905 w * Backward one window (and set window to N).
1906 ESC-SPACE * Forward one window, but don't stop at end-of-file.
1907 d ^D * Forward one half-window (and set half-window to N).
1908 u ^U * Backward one half-window (and set half-window to N).
1909 ESC-) RightArrow * Left one half screen width (or N positions).
1910 ESC-( LeftArrow * Right one half screen width (or N positions).
1911 F Forward forever; like "tail -f".
1912 r ^R ^L Repaint screen.
1913 R Repaint screen, discarding buffered input.
1914 ---------------------------------------------------
1915 Default "window" is the screen height.
1916 Default "half-window" is half of the screen height.
1917 ---------------------------------------------------------------------------
1919 /pattern * Search forward for (N-th) matching line.
1920 ?pattern * Search backward for (N-th) matching line.
1921 n * Repeat previous search (for N-th occurrence).
1922 N * Repeat previous search in reverse direction.
1923 ESC-n * Repeat previous search, spanning files.
1924 ESC-N * Repeat previous search, reverse dir. & spanning files.
1925 ESC-u Undo (toggle) search highlighting.
1926 ---------------------------------------------------
1927 Search patterns may be modified by one or more of:
1928 ^N or ! Search for NON-matching lines.
1929 ^E or * Search multiple files (pass thru END OF FILE).
1930 ^F or @ Start search at FIRST file (for /) or last file (for ?).
1931 ^K Highlight matches, but don't move (KEEP position).
1932 ^R Don't use REGULAR EXPRESSIONS.
1933 ---------------------------------------------------------------------------
1935 g < ESC-< * Go to first line in file (or line N).
1936 G > ESC-> * Go to last line in file (or line N).
1937 p % * Go to beginning of file (or N percent into file).
1938 t * Go to the (N-th) next tag.
1939 T * Go to the (N-th) previous tag.
1940 { ( [ * Find close bracket } ) ].
1941 } ) ] * Find open bracket { ( [.
1942 ESC-^F <c1> <c2> * Find close bracket <c2>.
1943 ESC-^B <c1> <c2> * Find open bracket <c1>
1944 ---------------------------------------------------
1945 Each "find close bracket" command goes forward to the close bracket
1946 matching the (N-th) open bracket in the top line.
1947 Each "find open bracket" command goes backward to the open bracket
1948 matching the (N-th) close bracket in the bottom line.
1949 m<letter> Mark the current position with <letter>.
1950 '<letter> Go to a previously marked position.
1951 '' Go to the previous position.
1953 ---------------------------------------------------
1954 A mark is any upper-case or lower-case letter.
1955 Certain marks are predefined:
1956 ^ means beginning of the file
1957 $ means end of the file
1958 ---------------------------------------------------------------------------
1960 :e [file] Examine a new file.
1962 :n * Examine the (N-th) next file from the command line.
1963 :p * Examine the (N-th) previous file from the command line.
1964 :x * Examine the first (or N-th) file from the command line.
1965 :d Delete the current file from the command line list.
1966 = ^G :f Print current file name.
1967 ---------------------------------------------------------------------------
1968 MISCELLANEOUS COMMANDS
1969 -<flag> Toggle a command line option [see OPTIONS below].
1970 --<name> Toggle a command line option, by name.
1971 _<flag> Display the setting of a command line option.
1972 __<name> Display the setting of an option, by name.
1973 +cmd Execute the less cmd each time a new file is examined.
1974 !command Execute the shell command with $SHELL.
1975 |Xcommand Pipe file between current pos & mark X to shell command.
1976 v Edit the current file with $VISUAL or $EDITOR.
1977 V Print version number of "less".
1978 ---------------------------------------------------------------------------
1980 Most options may be changed either on the command line,
1981 or from within less by using the - or -- command.
1982 Options may be given in one of two forms: either a single
1983 character preceded by a -, or a name preceded by --.
1985 Display help (from command line).
1986 -a ........ --search-skip-screen
1987 Forward search skips current screen.
1988 -b [N] .... --buffers=[N]
1990 -B ........ --auto-buffers
1991 Don't automatically allocate buffers for pipes.
1992 -c ........ --clear-screen
1993 Repaint by clearing rather than scrolling.
1996 -D [xn.n] . --color=xn.n
1997 Set screen colors. (MS-DOS only)
1998 -e -E .... --quit-at-eof --QUIT-AT-EOF
1999 Quit at end of file.
2001 Force open non-regular files.
2002 -F ........ --quit-if-one-screen
2003 Quit if entire file fits on first screen.
2004 -g ........ --hilite-search
2005 Highlight only last match for searches.
2006 -G ........ --HILITE-SEARCH
2007 Don't highlight any matches for searches.
2008 -h [N] .... --max-back-scroll=[N]
2009 Backward scroll limit.
2010 -i ........ --ignore-case
2011 Ignore case in searches that do not contain uppercase.
2012 -I ........ --IGNORE-CASE
2013 Ignore case in all searches.
2014 -j [N] .... --jump-target=[N]
2015 Screen position of target lines.
2016 -J ........ --status-column
2017 Display a status column at left edge of screen.
2018 -k [file] . --lesskey-file=[file]
2020 -L ........ --no-lessopen
2021 Ignore the LESSOPEN environment variable.
2022 -m -M .... --long-prompt --LONG-PROMPT
2024 -n -N .... --line-numbers --LINE-NUMBERS
2025 Don't use line numbers.
2026 -o [file] . --log-file=[file]
2027 Copy to log file (standard input only).
2028 -O [file] . --LOG-FILE=[file]
2029 Copy to log file (unconditionally overwrite).
2030 -p [pattern] --pattern=[pattern]
2031 Start at pattern (from command line).
2032 -P [prompt] --prompt=[prompt]
2034 -q -Q .... --quiet --QUIET --silent --SILENT
2035 Quiet the terminal bell.
2036 -r -R .... --raw-control-chars --RAW-CONTROL-CHARS
2037 Output "raw" control characters.
2038 -s ........ --squeeze-blank-lines
2039 Squeeze multiple blank lines.
2040 -S ........ --chop-long-lines
2042 -t [tag] .. --tag=[tag]
2044 -T [tagsfile] --tag-file=[tagsfile]
2045 Use an alternate tags file.
2046 -u -U .... --underline-special --UNDERLINE-SPECIAL
2047 Change handling of backspaces.
2048 -V ........ --version
2049 Display the version number of "less".
2050 -w ........ --hilite-unread
2051 Highlight first new line after forward-screen.
2052 -W ........ --HILITE-UNREAD
2053 Highlight first new line after any forward movement.
2054 -x [N[,...]] --tabs=[N[,...]]
2056 -X ........ --no-init
2057 Don't use termcap init/deinit strings.
2059 Don't use termcap keypad init/deinit strings.
2060 -y [N] .... --max-forw-scroll=[N]
2061 Forward scroll limit.
2062 -z [N] .... --window=[N]
2064 -" [c[c]] . --quotes=[c[c]]
2065 Set shell quote characters.
2067 Don't display tildes after end of file.
2068 -# [N] .... --shift=[N]
2069 Horizontal scroll amount (0 = one half screen width)
2071 ---------------------------------------------------------------------------
2073 These keys can be used to edit text being entered
2074 on the "command line" at the bottom of the screen.
2075 RightArrow ESC-l Move cursor right one character.
2076 LeftArrow ESC-h Move cursor left one character.
2077 CNTL-RightArrow ESC-RightArrow ESC-w Move cursor right one word.
2078 CNTL-LeftArrow ESC-LeftArrow ESC-b Move cursor left one word.
2079 HOME ESC-0 Move cursor to start of line.
2080 END ESC-$ Move cursor to end of line.
2081 BACKSPACE Delete char to left of cursor.
2082 DELETE ESC-x Delete char under cursor.
2083 CNTL-BACKSPACE ESC-BACKSPACE Delete word to left of cursor.
2084 CNTL-DELETE ESC-DELETE ESC-X Delete word under cursor.
2085 CNTL-U ESC (MS-DOS only) Delete entire line.
2086 UpArrow ESC-k Retrieve previous command line.
2087 DownArrow ESC-j Retrieve next command line.
2088 TAB Complete filename & cycle.
2089 SHIFT-TAB ESC-TAB Complete filename & reverse cycle.
2090 CNTL-L Complete filename, list all.