/* vi: set sw=4 ts=4: */ /* * Mini less implementation for busybox * * Copyright (C) 2005 by Rob Sullivan * * Licensed under GPLv2 or later, see file LICENSE in this source tree. */ /* * TODO: * - Add more regular expression support - search modifiers, certain matches, etc. * - Add more complex bracket searching - currently, nested brackets are * not considered. * - Add support for "F" as an input. This causes less to act in * a similar way to tail -f. * - Allow horizontal scrolling. * * Notes: * - the inp file pointer is used so that keyboard input works after * redirected input has been read from stdin */ //config:config LESS //config: bool "less (16 kb)" //config: default y //config: help //config: 'less' is a pager, meaning that it displays text files. It possesses //config: a wide array of features, and is an improvement over 'more'. //config: //config:config FEATURE_LESS_MAXLINES //config: int "Max number of input lines less will try to eat" //config: default 9999999 //config: depends on LESS //config: //config:config FEATURE_LESS_BRACKETS //config: bool "Enable bracket searching" //config: default y //config: depends on LESS //config: help //config: This option adds the capability to search for matching left and right //config: brackets, facilitating programming. //config: //config:config FEATURE_LESS_FLAGS //config: bool "Enable -m/-M" //config: default y //config: depends on LESS //config: help //config: The -M/-m flag enables a more sophisticated status line. //config: //config:config FEATURE_LESS_TRUNCATE //config: bool "Enable -S" //config: default y //config: depends on LESS //config: help //config: The -S flag causes long lines to be truncated rather than //config: wrapped. //config: //config:config FEATURE_LESS_MARKS //config: bool "Enable marks" //config: default y //config: depends on LESS //config: help //config: Marks enable positions in a file to be stored for easy reference. //config: //config:config FEATURE_LESS_REGEXP //config: bool "Enable regular expressions" //config: default y //config: depends on LESS //config: help //config: Enable regular expressions, allowing complex file searches. //config: //config:config FEATURE_LESS_WINCH //config: bool "Enable automatic resizing on window size changes" //config: default y //config: depends on LESS //config: help //config: Makes less track window size changes. //config: //config:config FEATURE_LESS_ASK_TERMINAL //config: bool "Use 'tell me cursor position' ESC sequence to measure window" //config: default y //config: depends on FEATURE_LESS_WINCH //config: help //config: Makes less track window size changes. //config: If terminal size can't be retrieved and $LINES/$COLUMNS are not set, //config: this option makes less perform a last-ditch effort to find it: //config: position cursor to 999,999 and ask terminal to report real //config: cursor position using "ESC [ 6 n" escape sequence, then read stdin. //config: This is not clean but helps a lot on serial lines and such. //config: //config:config FEATURE_LESS_DASHCMD //config: bool "Enable flag changes ('-' command)" //config: default y //config: depends on LESS //config: help //config: This enables the ability to change command-line flags within //config: less itself ('-' keyboard command). //config: //config:config FEATURE_LESS_LINENUMS //config: bool "Enable -N (dynamic switching of line numbers)" //config: default y //config: depends on FEATURE_LESS_DASHCMD //config: //config:config FEATURE_LESS_RAW //config: bool "Enable -R ('raw control characters')" //config: default y //config: depends on FEATURE_LESS_DASHCMD //config: help //config: This is essential for less applet to work with tools that use colors //config: and paging, such as git, systemd tools or nmcli. //config: //config:config FEATURE_LESS_ENV //config: bool "Take options from $LESS environment variable" //config: default y //config: depends on FEATURE_LESS_DASHCMD //config: help //config: This is essential for less applet to work with tools that use colors //config: and paging, such as git, systemd tools or nmcli. //applet:IF_LESS(APPLET(less, BB_DIR_USR_BIN, BB_SUID_DROP)) //kbuild:lib-$(CONFIG_LESS) += less.o //usage:#define less_trivial_usage //usage: "[-EF" IF_FEATURE_LESS_REGEXP("I")IF_FEATURE_LESS_FLAGS("Mm") //usage: "N" IF_FEATURE_LESS_TRUNCATE("S") IF_FEATURE_LESS_RAW("R") "h~] [FILE]..." //usage:#define less_full_usage "\n\n" //usage: "View FILE (or stdin) one screenful at a time\n" //usage: "\n -E Quit once the end of a file is reached" //usage: "\n -F Quit if entire file fits on first screen" //usage: IF_FEATURE_LESS_REGEXP( //usage: "\n -I Ignore case in all searches" //usage: ) //usage: IF_FEATURE_LESS_FLAGS( //usage: "\n -M,-m Display status line with line numbers" //usage: "\n and percentage through the file" //usage: ) //usage: "\n -N Prefix line number to each line" //usage: IF_FEATURE_LESS_TRUNCATE( //usage: "\n -S Truncate long lines" //usage: ) //usage: IF_FEATURE_LESS_RAW( //usage: "\n -R Remove color escape codes in input" //usage: ) //usage: "\n -~ Suppress ~s displayed past EOF" #include /* sched_yield() */ #include "libbb.h" #include "common_bufsiz.h" #if ENABLE_FEATURE_LESS_REGEXP #include "xregex.h" #endif #define ESC "\033" /* The escape codes for highlighted and normal text */ #define HIGHLIGHT ESC"[7m" #define NORMAL ESC"[m" /* The escape code to home and clear to the end of screen */ #define CLEAR ESC"[H"ESC"[J" /* The escape code to clear to the end of line */ #define CLEAR_2_EOL ESC"[K" enum { /* Absolute max of lines eaten */ MAXLINES = CONFIG_FEATURE_LESS_MAXLINES, /* This many "after the end" lines we will show (at max) */ TILDES = 1, }; /* Command line options */ enum { FLAG_E = 1 << 0, FLAG_M = 1 << 1, FLAG_m = 1 << 2, FLAG_N = 1 << 3, FLAG_TILDE = 1 << 4, FLAG_I = 1 << 5, FLAG_F = 1 << 6, FLAG_S = (1 << 7) * ENABLE_FEATURE_LESS_TRUNCATE, FLAG_R = (1 << 8) * ENABLE_FEATURE_LESS_RAW, /* hijack command line options variable for internal state vars */ LESS_STATE_MATCH_BACKWARDS = 1 << 15, }; #if !ENABLE_FEATURE_LESS_REGEXP enum { pattern_valid = 0 }; #endif struct globals { int cur_fline; /* signed */ int kbd_fd; /* fd to get input from */ int kbd_fd_orig_flags; int less_gets_pos; /* last position in last line, taking into account tabs */ size_t last_line_pos; unsigned max_fline; unsigned max_lineno; /* this one tracks linewrap */ unsigned max_displayed_line; unsigned width; #if ENABLE_FEATURE_LESS_WINCH unsigned winch_counter; #endif ssize_t eof_error; /* eof if 0, error if < 0 */ ssize_t readpos; ssize_t readeof; /* must be signed */ const char **buffer; const char **flines; const char *empty_line_marker; unsigned num_files; unsigned current_file; char *filename; char **files; #if ENABLE_FEATURE_LESS_FLAGS int num_lines; /* a flag if < 0, line count if >= 0 */ # define REOPEN_AND_COUNT (-1) # define REOPEN_STDIN (-2) # define NOT_REGULAR_FILE (-3) #endif #if ENABLE_FEATURE_LESS_MARKS unsigned num_marks; unsigned mark_lines[15][2]; #endif #if ENABLE_FEATURE_LESS_REGEXP unsigned *match_lines; int match_pos; /* signed! */ int wanted_match; /* signed! */ int num_matches; regex_t pattern; smallint pattern_valid; #endif #if ENABLE_FEATURE_LESS_RAW smallint in_escape; #endif #if ENABLE_FEATURE_LESS_ASK_TERMINAL smallint winsize_err; #endif smallint terminated; struct termios term_orig, term_less; char kbd_input[KEYCODE_BUFFER_SIZE]; }; #define G (*ptr_to_globals) #define cur_fline (G.cur_fline ) #define kbd_fd (G.kbd_fd ) #define less_gets_pos (G.less_gets_pos ) #define last_line_pos (G.last_line_pos ) #define max_fline (G.max_fline ) #define max_lineno (G.max_lineno ) #define max_displayed_line (G.max_displayed_line) #define width (G.width ) #define winch_counter (G.winch_counter ) /* This one is 100% not cached by compiler on read access */ #define WINCH_COUNTER (*(volatile unsigned *)&winch_counter) #define eof_error (G.eof_error ) #define readpos (G.readpos ) #define readeof (G.readeof ) #define buffer (G.buffer ) #define flines (G.flines ) #define empty_line_marker (G.empty_line_marker ) #define num_files (G.num_files ) #define current_file (G.current_file ) #define filename (G.filename ) #define files (G.files ) #define num_lines (G.num_lines ) #define num_marks (G.num_marks ) #define mark_lines (G.mark_lines ) #if ENABLE_FEATURE_LESS_REGEXP #define match_lines (G.match_lines ) #define match_pos (G.match_pos ) #define num_matches (G.num_matches ) #define wanted_match (G.wanted_match ) #define pattern (G.pattern ) #define pattern_valid (G.pattern_valid ) #endif #define terminated (G.terminated ) #define term_orig (G.term_orig ) #define term_less (G.term_less ) #define kbd_input (G.kbd_input ) #define INIT_G() do { \ SET_PTR_TO_GLOBALS(xzalloc(sizeof(G))); \ less_gets_pos = -1; \ empty_line_marker = "~"; \ current_file = 1; \ eof_error = 1; \ terminated = 1; \ IF_FEATURE_LESS_REGEXP(wanted_match = -1;) \ } while (0) /* flines[] are lines read from stdin, each in malloc'ed buffer. * Line numbers are stored as uint32_t prepended to each line. * Pointer is adjusted so that flines[i] points directly past * line number. Accessor: */ #define MEMPTR(p) ((char*)(p) - 4) #define LINENO(p) (*(uint32_t*)((p) - 4)) /* Reset terminal input to normal */ static void set_tty_cooked(void) { fflush_all(); tcsetattr(kbd_fd, TCSANOW, &term_orig); } /* Move the cursor to a position (x,y), where (0,0) is the top-left corner of the console */ static void move_cursor(int line, int col) { printf(ESC"[%u;%uH", line, col); } static void clear_line(void) { printf(ESC"[%u;0H" CLEAR_2_EOL, max_displayed_line + 2); } static void print_hilite(const char *str) { printf(HIGHLIGHT"%s"NORMAL, str); } static void print_statusline(const char *str) { clear_line(); printf(HIGHLIGHT"%.*s"NORMAL, width - 1, str); } /* Exit the program gracefully */ static void less_exit(int code) { set_tty_cooked(); if (!(G.kbd_fd_orig_flags & O_NONBLOCK)) ndelay_off(kbd_fd); clear_line(); if (code < 0) kill_myself_with_sig(- code); /* does not return */ exit(code); } #if (ENABLE_FEATURE_LESS_DASHCMD && ENABLE_FEATURE_LESS_LINENUMS) \ || ENABLE_FEATURE_LESS_WINCH static void re_wrap(void) { int w = width; int new_line_pos; int src_idx; int dst_idx; int new_cur_fline = 0; uint32_t lineno; char linebuf[w + 1]; const char **old_flines = flines; const char *s; char **new_flines = NULL; char *d; if (option_mask32 & FLAG_N) w -= 8; src_idx = 0; dst_idx = 0; s = old_flines[0]; lineno = LINENO(s); d = linebuf; new_line_pos = 0; while (1) { *d = *s; if (*d != '\0') { new_line_pos++; if (*d == '\t') { /* tab */ new_line_pos += 7; new_line_pos &= (~7); } s++; d++; if (new_line_pos >= w) { int sz; /* new line is full, create next one */ *d = '\0'; next_new: sz = (d - linebuf) + 1; /* + 1: NUL */ d = ((char*)xmalloc(sz + 4)) + 4; LINENO(d) = lineno; memcpy(d, linebuf, sz); new_flines = xrealloc_vector(new_flines, 8, dst_idx); new_flines[dst_idx] = d; dst_idx++; if (new_line_pos < w) { /* if we came here thru "goto next_new" */ if (src_idx > max_fline) break; lineno = LINENO(s); } d = linebuf; new_line_pos = 0; } continue; } /* *d == NUL: old line ended, go to next old one */ free(MEMPTR(old_flines[src_idx])); /* btw, convert cur_fline... */ if (cur_fline == src_idx) new_cur_fline = dst_idx; src_idx++; /* no more lines? finish last new line (and exit the loop) */ if (src_idx > max_fline) goto next_new; s = old_flines[src_idx]; if (lineno != LINENO(s)) { /* this is not a continuation line! * create next _new_ line too */ goto next_new; } } free(old_flines); flines = (const char **)new_flines; max_fline = dst_idx - 1; last_line_pos = new_line_pos; cur_fline = new_cur_fline; /* max_lineno is screen-size independent */ #if ENABLE_FEATURE_LESS_REGEXP pattern_valid = 0; #endif } #endif #if ENABLE_FEATURE_LESS_REGEXP static void fill_match_lines(unsigned pos); #else #define fill_match_lines(pos) ((void)0) #endif static int at_end(void) { return (option_mask32 & FLAG_S) ? !(cur_fline <= max_fline && max_lineno > LINENO(flines[cur_fline]) + max_displayed_line) : !(max_fline > cur_fline + max_displayed_line); } /* Devilishly complex routine. * * Has to deal with EOF and EPIPE on input, * with line wrapping, with last line not ending in '\n' * (possibly not ending YET!), with backspace and tabs. * It reads input again if last time we got an EOF (thus supporting * growing files) or EPIPE (watching output of slow process like make). * * Variables used: * flines[] - array of lines already read. Linewrap may cause * one source file line to occupy several flines[n]. * flines[max_fline] - last line, possibly incomplete. * terminated - 1 if flines[max_fline] is 'terminated' * (if there was '\n' [which isn't stored itself, we just remember * that it was seen]) * max_lineno - last line's number, this one doesn't increment * on line wrap, only on "real" new lines. * readbuf[0..readeof-1] - small preliminary buffer. * readbuf[readpos] - next character to add to current line. * last_line_pos - screen line position of next char to be read * (takes into account tabs and backspaces) * eof_error - < 0 error, == 0 EOF, > 0 not EOF/error * * "git log -p | less -m" on the kernel git tree is a good test for EAGAINs, * "/search on very long input" and "reaching max line count" corner cases. */ static void read_lines(void) { char *current_line, *p; int w = width; char last_terminated = terminated; time_t last_time = 0; int retry_EAGAIN = 2; #if ENABLE_FEATURE_LESS_REGEXP unsigned old_max_fline = max_fline; #endif #define readbuf bb_common_bufsiz1 setup_common_bufsiz(); /* (careful: max_fline can be -1) */ if (max_fline + 1 > MAXLINES) return; if (option_mask32 & FLAG_N) w -= 8; p = current_line = ((char*)xmalloc(w + 5)) + 4; if (!last_terminated) { const char *cp = flines[max_fline]; p = stpcpy(p, cp); free(MEMPTR(cp)); /* last_line_pos is still valid from previous read_lines() */ } else { max_fline++; last_line_pos = 0; } while (1) { /* read lines until we reach cur_fline or wanted_match */ *p = '\0'; terminated = 0; while (1) { /* read chars until we have a line */ char c; /* if no unprocessed chars left, eat more */ if (readpos >= readeof) { int flags = ndelay_on(0); while (1) { time_t t; errno = 0; eof_error = safe_read(STDIN_FILENO, readbuf, COMMON_BUFSIZE); if (errno != EAGAIN) break; t = time(NULL); if (t != last_time) { last_time = t; if (--retry_EAGAIN < 0) break; } sched_yield(); } fcntl(0, F_SETFL, flags); /* ndelay_off(0) */ readpos = 0; readeof = eof_error; if (eof_error <= 0) goto reached_eof; retry_EAGAIN = 1; } c = readbuf[readpos]; /* backspace? [needed for manpages] */ /* is (a) insane and */ /* (b) harder to do correctly, so we refuse to do it */ if (c == '\x8' && last_line_pos && p[-1] != '\t') { readpos++; /* eat it */ last_line_pos--; /* was buggy (p could end up <= current_line)... */ *--p = '\0'; continue; } #if ENABLE_FEATURE_LESS_RAW if (option_mask32 & FLAG_R) { if (c == '\033') goto discard; if (G.in_escape) { if (isdigit(c) || c == '[' || c == ';' || c == 'm' ) { discard: G.in_escape = (c != 'm'); readpos++; continue; } /* Hmm, unexpected end of "ESC [ N ; N m" sequence */ G.in_escape = 0; } } #endif { size_t new_last_line_pos = last_line_pos + 1; if (c == '\t') { new_last_line_pos += 7; new_last_line_pos &= (~7); } if ((int)new_last_line_pos > w) break; last_line_pos = new_last_line_pos; } /* ok, we will eat this char */ readpos++; if (c == '\n') { terminated = 1; last_line_pos = 0; break; } /* NUL is substituted by '\n'! */ if (c == '\0') c = '\n'; *p++ = c; *p = '\0'; } /* end of "read chars until we have a line" loop */ #if 0 //BUG: also triggers on this: // { printf "\nfoo\n"; sleep 1; printf "\nbar\n"; } | less // (resulting in lost empty line between "foo" and "bar" lines) // the "terminated" logic needs fixing (or explaining) /* Corner case: linewrap with only "" wrapping to next line */ /* Looks ugly on screen, so we do not store this empty line */ if (!last_terminated && !current_line[0]) { last_terminated = 1; max_lineno++; continue; } #endif reached_eof: last_terminated = terminated; flines = xrealloc_vector(flines, 8, max_fline); flines[max_fline] = (char*)xrealloc(MEMPTR(current_line), strlen(current_line) + 1 + 4) + 4; LINENO(flines[max_fline]) = max_lineno; if (terminated) max_lineno++; if (max_fline >= MAXLINES) { eof_error = 0; /* Pretend we saw EOF */ break; } if (!at_end()) { #if !ENABLE_FEATURE_LESS_REGEXP break; #else if (wanted_match >= num_matches) { /* goto_match called us */ fill_match_lines(old_max_fline); old_max_fline = max_fline; } if (wanted_match < num_matches) break; #endif } if (eof_error <= 0) { break; } max_fline++; current_line = ((char*)xmalloc(w + 5)) + 4; p = current_line; last_line_pos = 0; } /* end of "read lines until we reach cur_fline" loop */ if (eof_error < 0) { if (errno == EAGAIN) { eof_error = 1; } else { print_statusline(bb_msg_read_error); } } #if ENABLE_FEATURE_LESS_FLAGS else if (eof_error == 0) num_lines = max_lineno; #endif fill_match_lines(old_max_fline); #if ENABLE_FEATURE_LESS_REGEXP /* prevent us from being stuck in search for a match */ wanted_match = -1; #endif #undef readbuf } #if ENABLE_FEATURE_LESS_FLAGS static int safe_lineno(int fline) { if (fline >= max_fline) fline = max_fline - 1; /* also catches empty file (max_fline == 0) */ if (fline < 0) return 0; return LINENO(flines[fline]) + 1; } /* count number of lines in file */ static void update_num_lines(void) { int count, fd; struct stat stbuf; ssize_t len, i; char buf[4096]; /* only do this for regular files */ if (num_lines == REOPEN_AND_COUNT || num_lines == REOPEN_STDIN) { count = 0; fd = open("/proc/self/fd/0", O_RDONLY); if (fd < 0 && num_lines == REOPEN_AND_COUNT) { /* "filename" is valid only if REOPEN_AND_COUNT */ fd = open(filename, O_RDONLY); } if (fd < 0) { /* somebody stole my file! */ num_lines = NOT_REGULAR_FILE; return; } if (fstat(fd, &stbuf) != 0 || !S_ISREG(stbuf.st_mode)) { num_lines = NOT_REGULAR_FILE; goto do_close; } while ((len = safe_read(fd, buf, sizeof(buf))) > 0) { for (i = 0; i < len; ++i) { if (buf[i] == '\n' && ++count == MAXLINES) goto done; } } done: num_lines = count; do_close: close(fd); } } /* Print a status line if -M was specified */ static void m_status_print(void) { int first, last; unsigned percent; if (less_gets_pos >= 0) /* don't touch statusline while input is done! */ return; clear_line(); printf(HIGHLIGHT"%s", filename); if (num_files > 1) printf(" (file %i of %i)", current_file, num_files); first = safe_lineno(cur_fline); last = (option_mask32 & FLAG_S) ? MIN(first + max_displayed_line, max_lineno) : safe_lineno(cur_fline + max_displayed_line); printf(" lines %i-%i", first, last); update_num_lines(); if (num_lines >= 0) printf("/%i", num_lines); if (at_end()) { printf(" (END)"); if (num_files > 1 && current_file != num_files) printf(" - next: %s", files[current_file]); } else if (num_lines > 0) { percent = (100 * last + num_lines/2) / num_lines; printf(" %i%%", percent <= 100 ? percent : 100); } printf(NORMAL); } #endif /* Print the status line */ static void status_print(void) { const char *p; if (less_gets_pos >= 0) /* don't touch statusline while input is done! */ return; /* Change the status if flags have been set */ #if ENABLE_FEATURE_LESS_FLAGS if (option_mask32 & (FLAG_M|FLAG_m)) { m_status_print(); return; } /* No flags set */ #endif clear_line(); if (cur_fline && !at_end()) { bb_putchar(':'); return; } p = "(END)"; if (!cur_fline) p = filename; if (num_files > 1) { printf(HIGHLIGHT"%s (file %i of %i)"NORMAL, p, current_file, num_files); return; } print_hilite(p); } static const char controls[] ALIGN1 = /* NUL: never encountered; TAB: not converted */ /**/"\x01\x02\x03\x04\x05\x06\x07\x08" "\x0a\x0b\x0c\x0d\x0e\x0f" "\x10\x11\x12\x13\x14\x15\x16\x17\x18\x19\x1a\x1b\x1c\x1d\x1e\x1f" "\x7f\x9b"; /* DEL and infamous Meta-ESC :( */ static const char ctrlconv[] ALIGN1 = /* why 40 instead of 4a below? - it is a replacement for '\n'. * '\n' is a former NUL - we subst it with @, not J */ "\x40\x41\x42\x43\x44\x45\x46\x47\x48\x49\x40\x4b\x4c\x4d\x4e\x4f" "\x50\x51\x52\x53\x54\x55\x56\x57\x58\x59\x5a\x5b\x5c\x5d\x5e\x5f"; static void print_lineno(const char *line) { const char *fmt = " "; unsigned n = n; /* for compiler */ if (line != empty_line_marker) { /* Width of 7 preserves tab spacing in the text */ fmt = "%7u "; n = LINENO(line) + 1; if (n > 9999999 && MAXLINES > 9999999) { n %= 10000000; fmt = "%07u "; } } printf(fmt, n); } #if ENABLE_FEATURE_LESS_REGEXP static void print_found(const char *line) { int match_status; int eflags; char *growline; regmatch_t match_structs; char buf[width+1]; const char *str = line; char *p = buf; size_t n; while (*str) { n = strcspn(str, controls); if (n) { if (!str[n]) break; memcpy(p, str, n); p += n; str += n; } n = strspn(str, controls); memset(p, '.', n); p += n; str += n; } strcpy(p, str); /* buf[] holds quarantined version of str */ /* Each part of the line that matches has the HIGHLIGHT * and NORMAL escape sequences placed around it. * NB: we regex against line, but insert text * from quarantined copy (buf[]) */ str = buf; growline = NULL; eflags = 0; goto start; while (match_status == 0) { char *new = xasprintf("%s%.*s"HIGHLIGHT"%.*s"NORMAL, growline ? growline : "", (int)match_structs.rm_so, str, (int)(match_structs.rm_eo - match_structs.rm_so), str + match_structs.rm_so); free(growline); growline = new; str += match_structs.rm_eo; line += match_structs.rm_eo; eflags = REG_NOTBOL; start: /* Most of the time doesn't find the regex, optimize for that */ match_status = regexec(&pattern, line, 1, &match_structs, eflags); /* if even "" matches, treat it as "not a match" */ if (match_structs.rm_so >= match_structs.rm_eo) match_status = 1; } printf("%s%s\n", growline ? growline : "", str); free(growline); } #else void print_found(const char *line); #endif static void print_ascii(const char *str) { char buf[width+1]; char *p; size_t n; while (*str) { n = strcspn(str, controls); if (n) { if (!str[n]) break; printf("%.*s", (int) n, str); str += n; } n = strspn(str, controls); p = buf; do { if (*str == 0x7f) *p++ = '?'; else if (*str == (char)0x9b) /* VT100's CSI, aka Meta-ESC. Who's inventor? */ /* I want to know who committed this sin */ *p++ = '{'; else *p++ = ctrlconv[(unsigned char)*str]; str++; } while (--n); *p = '\0'; print_hilite(buf); } puts(str); } /* Print the buffer */ static void buffer_print(void) { unsigned i; move_cursor(0, 0); for (i = 0; i <= max_displayed_line; i++) { printf(CLEAR_2_EOL); if (option_mask32 & FLAG_N) print_lineno(buffer[i]); if (pattern_valid) print_found(buffer[i]); else print_ascii(buffer[i]); } if ((option_mask32 & (FLAG_E|FLAG_F)) && eof_error <= 0 ) { i = option_mask32 & FLAG_F ? 0 : cur_fline; if (max_fline - i <= max_displayed_line) less_exit(EXIT_SUCCESS); } status_print(); } static void buffer_fill_and_print(void) { unsigned i; #if ENABLE_FEATURE_LESS_TRUNCATE int fpos = cur_fline; if (option_mask32 & FLAG_S) { /* Go back to the beginning of this line */ while (fpos && LINENO(flines[fpos]) == LINENO(flines[fpos-1])) fpos--; } i = 0; while (i <= max_displayed_line && fpos <= max_fline) { int lineno = LINENO(flines[fpos]); buffer[i] = flines[fpos]; i++; do { fpos++; } while ((fpos <= max_fline) && (option_mask32 & FLAG_S) && lineno == LINENO(flines[fpos]) ); } #else for (i = 0; i <= max_displayed_line && cur_fline + i <= max_fline; i++) { buffer[i] = flines[cur_fline + i]; } #endif for (; i <= max_displayed_line; i++) { buffer[i] = empty_line_marker; } buffer_print(); } /* move cur_fline to a given line number, reading lines if necessary */ static void goto_lineno(int target) { if (target <= 0 ) { cur_fline = 0; } else if (target > LINENO(flines[cur_fline])) { retry: while (LINENO(flines[cur_fline]) != target && cur_fline < max_fline) ++cur_fline; /* target not reached but more input is available */ if (LINENO(flines[cur_fline]) != target && eof_error > 0) { read_lines(); goto retry; } } else { /* search backwards through already-read lines */ while (LINENO(flines[cur_fline]) != target && cur_fline > 0) --cur_fline; } } static void cap_cur_fline(void) { if ((option_mask32 & FLAG_S)) { if (cur_fline > max_fline) cur_fline = max_fline; if (LINENO(flines[cur_fline]) + max_displayed_line > max_lineno + TILDES) { goto_lineno(max_lineno - max_displayed_line + TILDES); read_lines(); } } else { if (cur_fline + max_displayed_line > max_fline + TILDES) cur_fline = max_fline - max_displayed_line + TILDES; if (cur_fline < 0) cur_fline = 0; } } /* Move the buffer up and down in the file in order to scroll */ static void buffer_down(int nlines) { if ((option_mask32 & FLAG_S)) goto_lineno(LINENO(flines[cur_fline]) + nlines); else cur_fline += nlines; read_lines(); cap_cur_fline(); buffer_fill_and_print(); } static void buffer_up(int nlines) { if ((option_mask32 & FLAG_S)) { goto_lineno(LINENO(flines[cur_fline]) - nlines); } else { cur_fline -= nlines; if (cur_fline < 0) cur_fline = 0; } read_lines(); buffer_fill_and_print(); } /* display a given line where the argument can be either an index into * the flines array or a line number */ static void buffer_to_line(int linenum, int is_lineno) { if (linenum <= 0) cur_fline = 0; else if (is_lineno) goto_lineno(linenum); else cur_fline = linenum; read_lines(); cap_cur_fline(); buffer_fill_and_print(); } static void buffer_line(int linenum) { buffer_to_line(linenum, FALSE); } static void buffer_lineno(int lineno) { buffer_to_line(lineno, TRUE); } static void open_file_and_read_lines(void) { if (filename) { xmove_fd(xopen(filename, O_RDONLY), STDIN_FILENO); #if ENABLE_FEATURE_LESS_FLAGS num_lines = REOPEN_AND_COUNT; #endif } else { /* "less" with no arguments in argv[] */ /* For status line only */ filename = xstrdup(bb_msg_standard_input); #if ENABLE_FEATURE_LESS_FLAGS num_lines = REOPEN_STDIN; #endif } readpos = 0; readeof = 0; last_line_pos = 0; terminated = 1; read_lines(); } /* Reinitialize everything for a new file - free the memory and start over */ static void reinitialize(void) { unsigned i; if (flines) { for (i = 0; i <= max_fline; i++) free(MEMPTR(flines[i])); free(flines); flines = NULL; } max_fline = -1; cur_fline = 0; max_lineno = 0; open_file_and_read_lines(); #if ENABLE_FEATURE_LESS_ASK_TERMINAL if (G.winsize_err) printf(ESC"[999;999H" ESC"[6n"); #endif buffer_fill_and_print(); } static int64_t getch_nowait(void) { int rd; int64_t key64; struct pollfd pfd[2]; pfd[0].fd = STDIN_FILENO; pfd[0].events = POLLIN; pfd[1].fd = kbd_fd; pfd[1].events = POLLIN; again: tcsetattr(kbd_fd, TCSANOW, &term_less); /* NB: select/poll returns whenever read will not block. Therefore: * if eof is reached, select/poll will return immediately * because read will immediately return 0 bytes. * Even if select/poll says that input is available, read CAN block * (switch fd into O_NONBLOCK'ed mode to avoid it) */ rd = 1; /* Are we interested in stdin? */ if (at_end()) { if (eof_error > 0) /* did NOT reach eof yet */ rd = 0; /* yes, we are interested in stdin */ } /* Position cursor if line input is done */ if (less_gets_pos >= 0) move_cursor(max_displayed_line + 2, less_gets_pos + 1); fflush_all(); if (kbd_input[0] == 0) { /* if nothing is buffered */ #if ENABLE_FEATURE_LESS_WINCH while (1) { int r; /* NB: SIGWINCH interrupts poll() */ r = poll(pfd + rd, 2 - rd, -1); if (/*r < 0 && errno == EINTR &&*/ winch_counter) return '\\'; /* anything which has no defined function */ if (r) break; } #else safe_poll(pfd + rd, 2 - rd, -1); #endif } /* We have kbd_fd in O_NONBLOCK mode, read inside read_key() * would not block even if there is no input available */ key64 = read_key(kbd_fd, kbd_input, /*timeout off:*/ -2); if ((int)key64 == -1) { if (errno == EAGAIN) { /* No keyboard input available. Since poll() did return, * we should have input on stdin */ read_lines(); buffer_fill_and_print(); goto again; } /* EOF/error (ssh session got killed etc) */ less_exit(EXIT_SUCCESS); } set_tty_cooked(); return key64; } /* Grab a character from input without requiring the return key. * May return KEYCODE_xxx values. * Note that this function works best with raw input. */ static int64_t less_getch(int pos) { int64_t key64; int key; again: less_gets_pos = pos; key = key64 = getch_nowait(); less_gets_pos = -1; /* Discard Ctrl-something chars. * (checking only lower 32 bits is a size optimization: * upper 32 bits are used only by KEYCODE_CURSOR_POS) */ if (key >= 0 && key < ' ' && key != 0x0d && key != 8) goto again; return key64; } static char* less_gets(int sz) { int c; unsigned i = 0; char *result = xzalloc(1); while (1) { c = '\0'; less_gets_pos = sz + i; c = getch_nowait(); if (c == 0x0d) { result[i] = '\0'; less_gets_pos = -1; return result; } if (c == 0x7f) c = 8; if (c == 8 && i) { printf("\x8 \x8"); i--; } if (c < ' ') /* filters out KEYCODE_xxx too (<0) */ continue; if (i >= width - sz - 1) continue; /* len limit */ bb_putchar(c); result[i++] = c; result = xrealloc(result, i+1); } } static void examine_file(void) { char *new_fname; print_statusline("Examine: "); new_fname = less_gets(sizeof("Examine: ") - 1); if (!new_fname[0]) { status_print(); err: free(new_fname); return; } if (access(new_fname, R_OK) != 0) { print_statusline("Cannot read this file"); goto err; } free(filename); filename = new_fname; /* files start by = argv. why we assume that argv is infinitely long?? files[num_files] = filename; current_file = num_files + 1; num_files++; */ files[0] = filename; num_files = current_file = 1; reinitialize(); } /* This function changes the file currently being paged. direction can be one of the following: * -1: go back one file * 0: go to the first file * 1: go forward one file */ static void change_file(int direction) { if (current_file != ((direction > 0) ? num_files : 1)) { current_file = direction ? current_file + direction : 1; free(filename); filename = xstrdup(files[current_file - 1]); reinitialize(); } else { print_statusline(direction > 0 ? "No next file" : "No previous file"); } } static void remove_current_file(void) { unsigned i; if (num_files < 2) return; if (current_file != 1) { change_file(-1); for (i = 3; i <= num_files; i++) files[i - 2] = files[i - 1]; num_files--; } else { change_file(1); for (i = 2; i <= num_files; i++) files[i - 2] = files[i - 1]; num_files--; current_file--; } } static void colon_process(void) { int keypress; /* Clear the current line and print a prompt */ print_statusline(" :"); keypress = less_getch(2); switch (keypress) { case 'd': remove_current_file(); break; case 'e': examine_file(); break; #if ENABLE_FEATURE_LESS_FLAGS case 'f': m_status_print(); break; #endif case 'n': change_file(1); break; case 'p': change_file(-1); break; case 'q': less_exit(EXIT_SUCCESS); break; case 'x': change_file(0); break; } } #if ENABLE_FEATURE_LESS_REGEXP static void normalize_match_pos(int match) { if (match >= num_matches) match = num_matches - 1; if (match < 0) match = 0; match_pos = match; } static void goto_match(int match) { if (!pattern_valid) return; if (match < 0) match = 0; /* Try to find next match if eof isn't reached yet */ if (match >= num_matches && eof_error > 0) { wanted_match = match; /* "I want to read until I see N'th match" */ read_lines(); } if (num_matches) { normalize_match_pos(match); buffer_line(match_lines[match_pos]); } else { print_statusline("No matches found"); } } static void fill_match_lines(unsigned pos) { if (!pattern_valid) return; /* Run the regex on each line of the current file */ while (pos <= max_fline) { /* If this line matches */ if (regexec(&pattern, flines[pos], 0, NULL, 0) == 0 /* and we didn't match it last time */ && !(num_matches && match_lines[num_matches-1] == pos) ) { match_lines = xrealloc_vector(match_lines, 4, num_matches); match_lines[num_matches++] = pos; } pos++; } } static void regex_process(void) { char *uncomp_regex, *err; /* Reset variables */ free(match_lines); match_lines = NULL; match_pos = 0; num_matches = 0; if (pattern_valid) { regfree(&pattern); pattern_valid = 0; } /* Get the uncompiled regular expression from the user */ clear_line(); bb_putchar((option_mask32 & LESS_STATE_MATCH_BACKWARDS) ? '?' : '/'); uncomp_regex = less_gets(1); if (!uncomp_regex[0]) { free(uncomp_regex); buffer_print(); return; } /* Compile the regex and check for errors */ err = regcomp_or_errmsg(&pattern, uncomp_regex, (option_mask32 & FLAG_I) ? REG_ICASE : 0); free(uncomp_regex); if (err) { print_statusline(err); free(err); return; } pattern_valid = 1; match_pos = 0; fill_match_lines(0); while (match_pos < num_matches) { if ((int)match_lines[match_pos] > cur_fline) break; match_pos++; } if (option_mask32 & LESS_STATE_MATCH_BACKWARDS) match_pos--; /* It's possible that no matches are found yet. * goto_match() will read input looking for match, * if needed */ goto_match(match_pos); } #endif static void number_process(int first_digit) { unsigned i; int num; int keypress; char num_input[sizeof(int)*4]; /* more than enough */ num_input[0] = first_digit; /* Clear the current line, print a prompt, and then print the digit */ clear_line(); printf(":%c", first_digit); /* Receive input until a letter is given */ i = 1; while (i < sizeof(num_input)-1) { keypress = less_getch(i + 1); if ((unsigned)keypress > 255 || !isdigit(keypress)) break; num_input[i] = keypress; bb_putchar(keypress); i++; } num_input[i] = '\0'; num = bb_strtou(num_input, NULL, 10); /* on format error, num == -1 */ if (num < 1 || num > MAXLINES) { buffer_print(); return; } /* We now know the number and the letter entered, so we process them */ switch (keypress) { case KEYCODE_DOWN: case 'z': case 'd': case 'e': case ' ': case '\015': buffer_down(num); break; case KEYCODE_UP: case 'b': case 'w': case 'y': case 'u': buffer_up(num); break; case 'g': case '<': case 'G': case '>': buffer_lineno(num - 1); break; case 'p': case '%': #if ENABLE_FEATURE_LESS_FLAGS update_num_lines(); num = num * (num_lines > 0 ? num_lines : max_lineno) / 100; #else num = num * max_lineno / 100; #endif buffer_lineno(num); break; #if ENABLE_FEATURE_LESS_REGEXP case 'n': goto_match(match_pos + num); break; case '/': option_mask32 &= ~LESS_STATE_MATCH_BACKWARDS; regex_process(); break; case '?': option_mask32 |= LESS_STATE_MATCH_BACKWARDS; regex_process(); break; #endif } } #if ENABLE_FEATURE_LESS_DASHCMD static void flag_change(void) { int keypress; clear_line(); bb_putchar('-'); keypress = less_getch(1); switch (keypress) { case 'M': option_mask32 ^= FLAG_M; break; case 'm': option_mask32 ^= FLAG_m; break; case 'E': option_mask32 ^= FLAG_E; break; case '~': option_mask32 ^= FLAG_TILDE; break; #if ENABLE_FEATURE_LESS_TRUNCATE case 'S': option_mask32 ^= FLAG_S; buffer_fill_and_print(); break; #endif #if ENABLE_FEATURE_LESS_LINENUMS case 'N': option_mask32 ^= FLAG_N; re_wrap(); buffer_fill_and_print(); break; #endif } } #ifdef BLOAT static void show_flag_status(void) { int keypress; int flag_val; clear_line(); bb_putchar('_'); keypress = less_getch(1); switch (keypress) { case 'M': flag_val = option_mask32 & FLAG_M; break; case 'm': flag_val = option_mask32 & FLAG_m; break; case '~': flag_val = option_mask32 & FLAG_TILDE; break; case 'N': flag_val = option_mask32 & FLAG_N; break; case 'E': flag_val = option_mask32 & FLAG_E; break; default: flag_val = 0; break; } clear_line(); printf(HIGHLIGHT"The status of the flag is: %u"NORMAL, flag_val != 0); } #endif #endif /* ENABLE_FEATURE_LESS_DASHCMD */ static void save_input_to_file(void) { const char *msg = ""; char *current_line; unsigned i; FILE *fp; print_statusline("Log file: "); current_line = less_gets(sizeof("Log file: ")-1); if (current_line[0]) { fp = fopen_for_write(current_line); if (!fp) { msg = "Error opening log file"; goto ret; } for (i = 0; i <= max_fline; i++) fprintf(fp, "%s\n", flines[i]); fclose(fp); msg = "Done"; } ret: print_statusline(msg); free(current_line); } #if ENABLE_FEATURE_LESS_MARKS static void add_mark(void) { int letter; print_statusline("Mark: "); letter = less_getch(sizeof("Mark: ") - 1); if (isalpha(letter)) { /* If we exceed 15 marks, start overwriting previous ones */ if (num_marks == 14) num_marks = 0; mark_lines[num_marks][0] = letter; mark_lines[num_marks][1] = cur_fline; num_marks++; } else { print_statusline("Invalid mark letter"); } } static void goto_mark(void) { int letter; int i; print_statusline("Go to mark: "); letter = less_getch(sizeof("Go to mark: ") - 1); clear_line(); if (isalpha(letter)) { for (i = 0; i <= num_marks; i++) if (letter == mark_lines[i][0]) { buffer_line(mark_lines[i][1]); break; } if (num_marks == 14 && letter != mark_lines[14][0]) print_statusline("Mark not set"); } else print_statusline("Invalid mark letter"); } #endif #if ENABLE_FEATURE_LESS_BRACKETS static char opp_bracket(char bracket) { switch (bracket) { case '{': case '[': /* '}' == '{' + 2. Same for '[' */ bracket++; case '(': /* ')' == '(' + 1 */ bracket++; break; case '}': case ']': bracket--; case ')': bracket--; break; }; return bracket; } static void match_right_bracket(char bracket) { unsigned i = cur_fline; if (i >= max_fline || strchr(flines[i], bracket) == NULL ) { print_statusline("No bracket in top line"); return; } bracket = opp_bracket(bracket); for (; i < max_fline; i++) { if (strchr(flines[i], bracket) != NULL) { /* * Line with matched right bracket becomes * last visible line */ buffer_line(i - max_displayed_line); return; } } print_statusline("No matching bracket found"); } static void match_left_bracket(char bracket) { int i = cur_fline + max_displayed_line; if (i >= max_fline || strchr(flines[i], bracket) == NULL ) { print_statusline("No bracket in bottom line"); return; } bracket = opp_bracket(bracket); for (; i >= 0; i--) { if (strchr(flines[i], bracket) != NULL) { /* * Line with matched left bracket becomes * first visible line */ buffer_line(i); return; } } print_statusline("No matching bracket found"); } #endif /* FEATURE_LESS_BRACKETS */ static void keypress_process(int keypress) { switch (keypress) { case KEYCODE_DOWN: case 'e': case 'j': case 0x0d: buffer_down(1); break; case KEYCODE_UP: case 'y': case 'k': buffer_up(1); break; case KEYCODE_PAGEDOWN: case ' ': case 'z': case 'f': buffer_down(max_displayed_line + 1); break; case KEYCODE_PAGEUP: case 'w': case 'b': buffer_up(max_displayed_line + 1); break; case 'd': buffer_down((max_displayed_line + 1) / 2); break; case 'u': buffer_up((max_displayed_line + 1) / 2); break; case KEYCODE_HOME: case 'g': case 'p': case '<': case '%': buffer_line(0); break; case KEYCODE_END: case 'G': case '>': cur_fline = MAXLINES; read_lines(); buffer_line(cur_fline); break; case 'q': case 'Q': less_exit(EXIT_SUCCESS); break; #if ENABLE_FEATURE_LESS_MARKS case 'm': add_mark(); buffer_print(); break; case '\'': goto_mark(); buffer_print(); break; #endif case 'r': case 'R': /* TODO: (1) also bind ^R, ^L to this? * (2) re-measure window size? */ buffer_print(); break; /*case 'R': full_repaint(); break;*/ case 's': save_input_to_file(); break; case 'E': examine_file(); break; #if ENABLE_FEATURE_LESS_FLAGS case '=': m_status_print(); break; #endif #if ENABLE_FEATURE_LESS_REGEXP case '/': option_mask32 &= ~LESS_STATE_MATCH_BACKWARDS; regex_process(); break; case 'n': goto_match(match_pos + 1); break; case 'N': goto_match(match_pos - 1); break; case '?': option_mask32 |= LESS_STATE_MATCH_BACKWARDS; regex_process(); break; #endif #if ENABLE_FEATURE_LESS_DASHCMD case '-': flag_change(); buffer_print(); break; #ifdef BLOAT case '_': show_flag_status(); break; #endif #endif #if ENABLE_FEATURE_LESS_BRACKETS case '{': case '(': case '[': match_right_bracket(keypress); break; case '}': case ')': case ']': match_left_bracket(keypress); break; #endif case ':': colon_process(); break; } if (isdigit(keypress)) number_process(keypress); } static void sig_catcher(int sig) { less_exit(- sig); } #if ENABLE_FEATURE_LESS_WINCH static void sigwinch_handler(int sig UNUSED_PARAM) { winch_counter++; } #endif int less_main(int argc, char **argv) MAIN_EXTERNALLY_VISIBLE; int less_main(int argc, char **argv) { char *tty_name; int tty_fd; INIT_G(); /* TODO: -x: do not interpret backspace, -xx: tab also * -xxx: newline also * -w N: assume width N (-xxx -w 32: hex viewer of sorts) * -s: condense many empty lines to one * (used by some setups for manpage display) */ getopt32(argv, "EMmN~IF" IF_FEATURE_LESS_TRUNCATE("S") IF_FEATURE_LESS_RAW("R") /*ignored:*/"s" ); argv += optind; num_files = argc - optind; files = argv; /* Tools typically pass LESS="FRSXMK". * The options we don't understand are ignored. */ if (ENABLE_FEATURE_LESS_ENV) { char *c = getenv("LESS"); if (c) while (*c) switch (*c++) { case 'F': option_mask32 |= FLAG_F; break; case 'M': option_mask32 |= FLAG_M; break; case 'R': option_mask32 |= FLAG_R; break; case 'S': option_mask32 |= FLAG_S; break; default: break; } } /* Another popular pager, most, detects when stdout * is not a tty and turns into cat. This makes sense. */ if (!isatty(STDOUT_FILENO)) return bb_cat(argv); if (!num_files) { if (isatty(STDIN_FILENO)) { /* Just "less"? No args and no redirection? */ bb_show_usage(); } } else { filename = xstrdup(files[0]); } if (option_mask32 & FLAG_TILDE) empty_line_marker = ""; /* Some versions of less can survive w/o controlling tty, * try to do the same. This also allows to specify an alternative * tty via "less 1<>TTY". * * We prefer not to use STDOUT_FILENO directly, * since we want to set this fd to non-blocking mode, * and not interfere with other processes which share stdout with us. */ tty_name = xmalloc_ttyname(STDOUT_FILENO); if (tty_name) { tty_fd = open(tty_name, O_RDONLY); free(tty_name); if (tty_fd < 0) goto try_ctty; } else { /* Try controlling tty */ try_ctty: tty_fd = open(CURRENT_TTY, O_RDONLY); if (tty_fd < 0) { /* If all else fails, less 481 uses stdout. Mimic that */ tty_fd = STDOUT_FILENO; } } G.kbd_fd_orig_flags = ndelay_on(tty_fd); kbd_fd = tty_fd; /* save in a global */ get_termios_and_make_raw(tty_fd, &term_less, &term_orig, TERMIOS_RAW_CRNL_INPUT); IF_FEATURE_LESS_ASK_TERMINAL(G.winsize_err =) get_terminal_width_height(tty_fd, &width, &max_displayed_line); /* 20: two tabstops + 4 */ if (width < 20 || max_displayed_line < 3) return bb_cat(argv); max_displayed_line -= 2; /* We want to restore term_orig on exit */ bb_signals(BB_FATAL_SIGS, sig_catcher); #if ENABLE_FEATURE_LESS_WINCH signal(SIGWINCH, sigwinch_handler); #endif buffer = xmalloc((max_displayed_line+1) * sizeof(char *)); reinitialize(); while (1) { int64_t keypress; #if ENABLE_FEATURE_LESS_WINCH while (WINCH_COUNTER) { again: winch_counter--; IF_FEATURE_LESS_ASK_TERMINAL(G.winsize_err =) get_terminal_width_height(kbd_fd, &width, &max_displayed_line); IF_FEATURE_LESS_ASK_TERMINAL(got_size:) /* 20: two tabstops + 4 */ if (width < 20) width = 20; if (max_displayed_line < 3) max_displayed_line = 3; max_displayed_line -= 2; free(buffer); buffer = xmalloc((max_displayed_line+1) * sizeof(char *)); /* Avoid re-wrap and/or redraw if we already know * we need to do it again. These ops are expensive */ if (WINCH_COUNTER) goto again; re_wrap(); if (WINCH_COUNTER) goto again; buffer_fill_and_print(); /* This took some time. Loop back and check, * were there another SIGWINCH? */ } keypress = less_getch(-1); /* -1: do not position cursor */ # if ENABLE_FEATURE_LESS_ASK_TERMINAL if ((int32_t)keypress == KEYCODE_CURSOR_POS) { uint32_t rc = (keypress >> 32); width = (rc & 0x7fff); max_displayed_line = ((rc >> 16) & 0x7fff); goto got_size; } # endif #else keypress = less_getch(-1); /* -1: do not position cursor */ #endif keypress_process(keypress); } } /* Help text of less version 418 is below. If you are implementing something, keeping key and/or command line switch compatibility is a good idea: SUMMARY OF LESS COMMANDS Commands marked with * may be preceded by a number, N. Notes in parentheses indicate the behavior if N is given. h H Display this help. q :q Q :Q ZZ Exit. --------------------------------------------------------------------------- MOVING e ^E j ^N CR * Forward one line (or N lines). y ^Y k ^K ^P * Backward one line (or N lines). f ^F ^V SPACE * Forward one window (or N lines). b ^B ESC-v * Backward one window (or N lines). z * Forward one window (and set window to N). w * Backward one window (and set window to N). ESC-SPACE * Forward one window, but don't stop at end-of-file. d ^D * Forward one half-window (and set half-window to N). u ^U * Backward one half-window (and set half-window to N). ESC-) RightArrow * Left one half screen width (or N positions). ESC-( LeftArrow * Right one half screen width (or N positions). F Forward forever; like "tail -f". r ^R ^L Repaint screen. R Repaint screen, discarding buffered input. --------------------------------------------------- Default "window" is the screen height. Default "half-window" is half of the screen height. --------------------------------------------------------------------------- SEARCHING /pattern * Search forward for (N-th) matching line. ?pattern * Search backward for (N-th) matching line. n * Repeat previous search (for N-th occurrence). N * Repeat previous search in reverse direction. ESC-n * Repeat previous search, spanning files. ESC-N * Repeat previous search, reverse dir. & spanning files. ESC-u Undo (toggle) search highlighting. --------------------------------------------------- Search patterns may be modified by one or more of: ^N or ! Search for NON-matching lines. ^E or * Search multiple files (pass thru END OF FILE). ^F or @ Start search at FIRST file (for /) or last file (for ?). ^K Highlight matches, but don't move (KEEP position). ^R Don't use REGULAR EXPRESSIONS. --------------------------------------------------------------------------- JUMPING g < ESC-< * Go to first line in file (or line N). G > ESC-> * Go to last line in file (or line N). p % * Go to beginning of file (or N percent into file). t * Go to the (N-th) next tag. T * Go to the (N-th) previous tag. { ( [ * Find close bracket } ) ]. } ) ] * Find open bracket { ( [. ESC-^F * Find close bracket . ESC-^B * Find open bracket --------------------------------------------------- Each "find close bracket" command goes forward to the close bracket matching the (N-th) open bracket in the top line. Each "find open bracket" command goes backward to the open bracket matching the (N-th) close bracket in the bottom line. m Mark the current position with . ' Go to a previously marked position. '' Go to the previous position. ^X^X Same as '. --------------------------------------------------- A mark is any upper-case or lower-case letter. Certain marks are predefined: ^ means beginning of the file $ means end of the file --------------------------------------------------------------------------- CHANGING FILES :e [file] Examine a new file. ^X^V Same as :e. :n * Examine the (N-th) next file from the command line. :p * Examine the (N-th) previous file from the command line. :x * Examine the first (or N-th) file from the command line. :d Delete the current file from the command line list. = ^G :f Print current file name. --------------------------------------------------------------------------- MISCELLANEOUS COMMANDS - Toggle a command line option [see OPTIONS below]. -- Toggle a command line option, by name. _ Display the setting of a command line option. __ Display the setting of an option, by name. +cmd Execute the less cmd each time a new file is examined. !command Execute the shell command with $SHELL. |Xcommand Pipe file between current pos & mark X to shell command. v Edit the current file with $VISUAL or $EDITOR. V Print version number of "less". --------------------------------------------------------------------------- OPTIONS Most options may be changed either on the command line, or from within less by using the - or -- command. Options may be given in one of two forms: either a single character preceded by a -, or a name preceded by --. -? ........ --help Display help (from command line). -a ........ --search-skip-screen Forward search skips current screen. -b [N] .... --buffers=[N] Number of buffers. -B ........ --auto-buffers Don't automatically allocate buffers for pipes. -c ........ --clear-screen Repaint by clearing rather than scrolling. -d ........ --dumb Dumb terminal. -D [xn.n] . --color=xn.n Set screen colors. (MS-DOS only) -e -E .... --quit-at-eof --QUIT-AT-EOF Quit at end of file. -f ........ --force Force open non-regular files. -F ........ --quit-if-one-screen Quit if entire file fits on first screen. -g ........ --hilite-search Highlight only last match for searches. -G ........ --HILITE-SEARCH Don't highlight any matches for searches. -h [N] .... --max-back-scroll=[N] Backward scroll limit. -i ........ --ignore-case Ignore case in searches that do not contain uppercase. -I ........ --IGNORE-CASE Ignore case in all searches. -j [N] .... --jump-target=[N] Screen position of target lines. -J ........ --status-column Display a status column at left edge of screen. -k [file] . --lesskey-file=[file] Use a lesskey file. -L ........ --no-lessopen Ignore the LESSOPEN environment variable. -m -M .... --long-prompt --LONG-PROMPT Set prompt style. -n -N .... --line-numbers --LINE-NUMBERS Don't use line numbers. -o [file] . --log-file=[file] Copy to log file (standard input only). -O [file] . --LOG-FILE=[file] Copy to log file (unconditionally overwrite). -p [pattern] --pattern=[pattern] Start at pattern (from command line). -P [prompt] --prompt=[prompt] Define new prompt. -q -Q .... --quiet --QUIET --silent --SILENT Quiet the terminal bell. -r -R .... --raw-control-chars --RAW-CONTROL-CHARS Output "raw" control characters. -s ........ --squeeze-blank-lines Squeeze multiple blank lines. -S ........ --chop-long-lines Chop long lines. -t [tag] .. --tag=[tag] Find a tag. -T [tagsfile] --tag-file=[tagsfile] Use an alternate tags file. -u -U .... --underline-special --UNDERLINE-SPECIAL Change handling of backspaces. -V ........ --version Display the version number of "less". -w ........ --hilite-unread Highlight first new line after forward-screen. -W ........ --HILITE-UNREAD Highlight first new line after any forward movement. -x [N[,...]] --tabs=[N[,...]] Set tab stops. -X ........ --no-init Don't use termcap init/deinit strings. --no-keypad Don't use termcap keypad init/deinit strings. -y [N] .... --max-forw-scroll=[N] Forward scroll limit. -z [N] .... --window=[N] Set size of window. -" [c[c]] . --quotes=[c[c]] Set shell quote characters. -~ ........ --tilde Don't display tildes after end of file. -# [N] .... --shift=[N] Horizontal scroll amount (0 = one half screen width) --------------------------------------------------------------------------- LINE EDITING These keys can be used to edit text being entered on the "command line" at the bottom of the screen. RightArrow ESC-l Move cursor right one character. LeftArrow ESC-h Move cursor left one character. CNTL-RightArrow ESC-RightArrow ESC-w Move cursor right one word. CNTL-LeftArrow ESC-LeftArrow ESC-b Move cursor left one word. HOME ESC-0 Move cursor to start of line. END ESC-$ Move cursor to end of line. BACKSPACE Delete char to left of cursor. DELETE ESC-x Delete char under cursor. CNTL-BACKSPACE ESC-BACKSPACE Delete word to left of cursor. CNTL-DELETE ESC-DELETE ESC-X Delete word under cursor. CNTL-U ESC (MS-DOS only) Delete entire line. UpArrow ESC-k Retrieve previous command line. DownArrow ESC-j Retrieve next command line. TAB Complete filename & cycle. SHIFT-TAB ESC-TAB Complete filename & reverse cycle. CNTL-L Complete filename, list all. */