Mercurial > hg > Applications > mh
diff miscellany/less-177/less.man @ 0:bce86c4163a3
Initial revision
| author | kono |
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| date | Mon, 18 Apr 2005 23:46:02 +0900 |
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--- /dev/null Thu Jan 01 00:00:00 1970 +0000 +++ b/miscellany/less-177/less.man Mon Apr 18 23:46:02 2005 +0900 @@ -0,0 +1,1188 @@ + + + +LESS(1) LESS(1) + + +NNAAMMEE + less - opposite of more + +SSYYNNOOPPSSIISS + lleessss --?? + lleessss [[--[[++]]aaBBccCCddeeEEffHHiimmMMnnNNqqQQrrssSSuuUUww]] + [[--bb _b_u_f_s]] [[--hh _l_i_n_e_s]] [[--jj _l_i_n_e]] [[--kk _k_e_y_f_i_l_e]] + [[--{{ooOO}} _l_o_g_f_i_l_e]] [[--pp _p_a_t_t_e_r_n]] [[--PP _p_r_o_m_p_t]] [[--tt _t_a_g]] + [[--TT _t_a_g_f_i_l_e]] [[--xx _t_a_b]] [[--yy _l_i_n_e_s]] [[--[[zz]] _l_i_n_e_s]] + [[++[[++]]_c_m_d]] [[_f_i_l_e_n_a_m_e]]...... + + +DDEESSCCRRIIPPTTIIOONN + _L_e_s_s is a program similar to _m_o_r_e (1), but which allows + backward movement in the file as well as forward movement. + Also, _l_e_s_s does not have to read the entire input file + before starting, so with large input files it starts up + faster than text editors like _v_i (1). _L_e_s_s uses termcap + (or terminfo on some systems), so it can run on a variety + of terminals. There is even limited support for hardcopy + terminals. (On a hardcopy terminal, lines which should be + printed at the top of the screen are prefixed with an up- + arrow.) + + Commands are based on both _m_o_r_e and _v_i_. Commands may be + preceded by a decimal number, called N in the descriptions + below. The number is used by some commands, as indicated. + + +CCOOMMMMAANNDDSS + In the following descriptions, ^X means control-X. ESC + stands for the ESCAPE key; for example ESC-v means the two + character sequence "ESCAPE", then "v". + + h or H Help: display a summary of these commands. If you + forget all the other commands, remember this one. + + + SPACE or ^V or f or ^F + Scroll forward N lines, default one window (see + option -z below). If N is more than the screen + size, only the final screenful is displayed. Warn- + ing: some systems use ^V as a special literaliza- + tion character. + + + z Like SPACE, but if N is specified, it becomes the + new window size. + + + RETURN or ^N or e or ^E or j or ^J + Scroll forward N lines, default 1. The entire N + lines are displayed, even if N is more than the + screen size. + + + + 1 + + + + + +LESS(1) LESS(1) + + + d or ^D + Scroll forward N lines, default one half of the + screen size. If N is specified, it becomes the new + default for subsequent d and u commands. + + + b or ^B or ESC-v + Scroll backward N lines, default one window (see + option -z below). If N is more than the screen + size, only the final screenful is displayed. + + + w Like ESC-v, but if N is specified, it becomes the + new window size. + + + y or ^Y or ^P or k or ^K + Scroll backward N lines, default 1. The entire N + lines are displayed, even if N is more than the + screen size. Warning: some systems use ^Y as a + special job control character. + + + u or ^U + Scroll backward N lines, default one half of the + screen size. If N is specified, it becomes the new + default for subsequent d and u commands. + + + r or ^R or ^L + Repaint the screen. + + + R Repaint the screen, discarding any buffered input. + Useful if the file is changing while it is being + viewed. + + + F Scroll forward, and keep trying to read when the + end of file is reached. Normally this command + would be used when already at the end of the file. + It is a way to monitor the tail of a file which is + growing while it is being viewed. (The behavior is + similar to the "tail -f" command.) + + + g or < or ESC-< + Go to line N in the file, default 1 (beginning of + file). (Warning: this may be slow if N is large.) + + + G or > or ESC-> + Go to line N in the file, default the end of the + file. (Warning: this may be slow if N is large, or + + + + 2 + + + + + +LESS(1) LESS(1) + + + if N is not specified and standard input, rather + than a file, is being read.) + + + p or % Go to a position N percent into the file. N should + be between 0 and 100. (This works if standard + input is being read, but only if _l_e_s_s has already + read to the end of the file. It is always fast, + but not always useful.) + + + { If a left curly bracket appears in the top line + displayed on the screen, the { command will go to + the matching right curly bracket. The matching + right curly bracket is positioned on the bottom + line of the screen. If there is more than one left + curly bracket on the top line, a number N may be + used to specify the N-th bracket on the line. + + + } If a right curly bracket appears in the bottom line + displayed on the screen, the } command will go to + the matching left curly bracket. The matching left + curly bracket is positioned on the top line of the + screen. If there is more than one right curly + bracket on the top line, a number N may be used to + specify the N-th bracket on the line. + + + ( Like {, but applies to parentheses rather than + curly brackets. + + + ) Like }, but applies to parentheses rather than + curly brackets. + + + [ Like {, but applies to square brackets rather than + curly brackets. + + + ] Like }, but applies to square brackets rather than + curly brackets. + + + ESC-^F Followed by two characters, acts like {, but uses + the two characters as open and close brackets, + respectively. For example, "ESC ^F < >" could be + used to go forward to the > which matches the < in + the top displayed line. + + ESC-^B Followed by two characters, acts like }, but uses + the two characters as open and close brackets, + respectively. For example, "ESC ^B < >" could be + + + + 3 + + + + + +LESS(1) LESS(1) + + + used to go backward to the < which matches the > in + the bottom displayed line. + + m Followed by any lowercase letter, marks the current + position with that letter. + + + ' (Single quote.) Followed by any lowercase letter, + returns to the position which was previously marked + with that letter. Followed by another single + quote, returns to the position at which the last + "large" movement command was executed. Followed by + a ^ or $, jumps to the beginning or end of the file + respectively. Marks are preserved when a new file + is examined, so the ' command can be used to switch + between input files. + + + ^X^X Same as single quote. + + + /pattern + Search forward in the file for the N-th line con- + taining the pattern. N defaults to 1. The pattern + is a regular expression, as recognized by _e_d_. The + search starts at the second line displayed (but see + the -a and -j options, which change this). + + Certain characters are special if entered at the + beginning of the pattern; they modify the type of + search rather than become part of the pattern: + + ! Search for lines which do NOT match the pat- + tern. + + * Search multiple files. That is, if the + search reaches the end of the current file + without finding a match, the search contin- + ues in the next file in the command line + list. + + @ Begin the search at the first line of the + first file in the command line list, regard- + less of what is currently displayed on the + screen or the settings of the -a or -j + options. + + + ?pattern + Search backward in the file for the N-th line con- + taining the pattern. The search starts at the line + immediately before the top line displayed. + + Certain characters are special as in the / command: + + + + 4 + + + + + +LESS(1) LESS(1) + + + ! Search for lines which do NOT match the pat- + tern. + + * Search multiple files. That is, if the + search reaches the beginning of the current + file without finding a match, the search + continues in the previous file in the com- + mand line list. + + @ Begin the search at the last line of the + last file in the command line list, regard- + less of what is currently displayed on the + screen or the settings of the -a or -j + options. + + + ESC-/pattern + Same as "/*". + + + ESC-?pattern + Same as "?*". + + + n Repeat previous search, for N-th line containing + the last pattern. If the previous search was modi- + fied by !, the search is made for the N-th line NOT + containing the pattern. If the previous search was + modified by *, the search continues in the next (or + previous) file if not satisfied in the current + file. There is no effect if the previous search + was modified by @. + + + N Repeat previous search, but in the reverse direc- + tion. + + + ESC-n Repeat previous search, but crossing file bound- + aries. The effect is as if the previous search + were modified by *. + + + ESC-N Repeat previous search, but in the reverse direc- + tion and crossing file boundaries. + + + :e [filename] + Examine a new file. If the filename is missing, + the "current" file (see the :n and :p commands + below) from the list of files in the command line + is re-examined. A percent sign (%) in the filename + is replaced by the name of the current file. A + pound sign (#) is replaced by the name of the + + + + 5 + + + + + +LESS(1) LESS(1) + + + previously examined file. The filename is inserted + into the command line list of files so that it can + be seen by subsequent :n and :p commands. If the + filename consists of several files, they are all + inserted into the list of files and the first one + is examined. + + + ^X^V or E + Same as :e. Warning: some systems use ^V as a spe- + cial literalization character. + + + :n Examine the next file (from the list of files given + in the command line). If a number N is specified, + the N-th next file is examined. + + + :p Examine the previous file in the command line list. + If a number N is specified, the N-th previous file + is examined. + + + :x Examine the first file in the command line list. + If a number N is specified, the N-th file in the + list is examined. + + + = or ^G or :f + Prints some information about the file being + viewed, including its name and the line number and + byte offset of the bottom line being displayed. If + possible, it also prints the length of the file, + the number of lines in the file and the percent of + the file above the last displayed line. + + + - Followed by one of the command line option letters + (see below), this will change the setting of that + option and print a message describing the new set- + ting. If the option letter has a numeric value + (such as -b or -h), or a string value (such as -P + or -t), a new value may be entered after the option + letter. If no new value is entered, a message + describing the current setting is printed and noth- + ing is changed. + + + -+ Followed by one of the command line option letters + (see below), this will reset the option to its + default setting and print a message describing the + new setting. (The "-+_X" command does the same + thing as "-+_X" on the command line.) This does not + work for string-valued options. + + + + 6 + + + + + +LESS(1) LESS(1) + + + -- Followed by one of the command line option letters + (see below), this will reset the option to the + "opposite" of its default setting and print a mes- + sage describing the new setting. (The "--_X" com- + mand does the same thing as "-_X" on the command + line.) This does not work for numeric or string- + valued options. + + + _ (Underscore.) Followed by one of the command line + option letters (see below), this will print a mes- + sage describing the current setting of that option. + The setting of the option is not changed. + + + +cmd Causes the specified cmd to be executed each time a + new file is examined. For example, +G causes _l_e_s_s + to initially display each file starting at the end + rather than the beginning. + + + V Prints the version number of _l_e_s_s being run. + + + q or :q or :Q or ZZ or ESC ESC + Exits _l_e_s_s_. + + The following three commands may or may not be valid, + depending on your particular installation. + + + v Invokes an editor to edit the current file being + viewed. The editor is taken from the environment + variable EDITOR, or defaults to "vi". See also the + discussion of LESSEDIT under the section on PROMPTS + below. + + + ! shell-command + Invokes a shell to run the shell-command given. A + percent sign (%) in the command is replaced by the + name of the current file. A pound sign (#) is + replaced by the name of the previously examined + file. "!!" repeats the last shell command. "!" + with no shell command simply invokes a shell. In + all cases, the shell is taken from the environment + variable SHELL, or defaults to "sh". + + + | <m> shell-command + <m> represents any mark letter. Pipes a section of + the input file to the given shell command. The + section of the file to be piped is between the + first line on the current screen and the position + + + + 7 + + + + + +LESS(1) LESS(1) + + + marked by the letter. <m> may also be ^ or $ to + indicate beginning or end of file respectively. If + <m> is . or newline, the current screen is piped. + + +OOPPTTIIOONNSS + Command line options are described below. Most options + may be changed while _l_e_s_s is running, via the "-" command. + + Options are also taken from the environment variable + "LESS". For example, to avoid typing "less -options ..." + each time _l_e_s_s is invoked, you might tell _c_s_h_: + + setenv LESS "-options" + + or if you use _s_h_: + + LESS="-options"; export LESS + + The environment variable is parsed before the command + line, so command line options override the LESS environ- + ment variable. If an option appears in the LESS variable, + it can be reset to its default on the command line by + beginning the command line option with "-+". + + A dollar sign ($) may be used to signal the end of an + option string. This is important only for options like -P + which take a following string. + + -? This option displays a summary of the commands + accepted by _l_e_s_s (the same as the h command). If + this option is given, all other options are + ignored, and _l_e_s_s exits after the help screen is + viewed. (Depending on how your shell interprets + the question mark, it may be necessary to quote the + question mark, thus: "-\?".) + + -a Causes searches to start after the last line dis- + played on the screen, thus skipping all lines dis- + played on the screen. By default, searches start + at the second line on the screen (or after the last + found line; see the -j option). + + -b_n Causes _l_e_s_s to use a non-standard number of + buffers. Buffers are 1K, and by default 10 buffers + are used (except if data in coming from standard + input; see the -B option). The number _n specifies + a different number of buffers to use. + + -B Disables automatic allocation of buffers, so that + only the default number of buffers are used. If + more data is read than will fit in the buffers, the + oldest data is discarded. By default, when data is + coming from standard input, buffers are allocated + + + + 8 + + + + + +LESS(1) LESS(1) + + + automatically as needed to avoid loss of data. + + -c Causes full screen repaints to be painted from the + top line down. By default, full screen repaints + are done by scrolling from the bottom of the + screen. + + -C The -C option is like -c, but the screen is cleared + before it is repainted. + + -d The -d option suppresses the error message normally + displayed if the terminal is dumb; that is, lacks + some important capability, such as the ability to + clear the screen or scroll backward. The -d option + does not otherwise change the behavior of _l_e_s_s on a + dumb terminal). + + -e Causes _l_e_s_s to automatically exit the second time + it reaches end-of-file. By default, the only way + to exit _l_e_s_s is via the "q" command. + + -E Causes _l_e_s_s to automatically exit the first time it + reaches end-of-file. + + -f Forces non-regular files to be opened. (A non- + regular file is a directory or a device special + file.) Also suppresses the warning message when a + binary file is opened. By default, _l_e_s_s will + refuse to open non-regular files. + + -h_n Specifies a maximum number of lines to scroll back- + ward. If it is necessary to scroll backward more + than _n lines, the screen is repainted in a forward + direction instead. (If the terminal does not have + the ability to scroll backward, -h0 is implied.) + + -i Causes searches to ignore case; that is, uppercase + and lowercase are considered identical. Also, text + which is overstruck or underlined can be searched + for. This option is ignored if any uppercase let- + ters appear in the search pattern. + + -j_n Specifies a line on the screen where "target" lines + are to be positioned. Target lines are the object + of text searches, tag searches, jumps to a line + number, jumps to a file percentage, and jumps to a + marked position. The screen line is specified by a + number: the top line on the screen is 1, the next + is 2, and so on. The number may be negative to + specify a line relative to the bottom of the + screen: the bottom line on the screen is -1, the + second to the bottom is -2, and so on. If the -j + option is used, searches begin at the line immedi- + ately after the target line. For example, if "-j4" + + + + 9 + + + + + +LESS(1) LESS(1) + + + is used, the target line is the fourth line on the + screen, so searches begin at the fifth line on the + screen. + + -k_f_i_l_e_n_a_m_e + Causes _l_e_s_s to open and interpret the named file as + a _l_e_s_s_k_e_y (1) file. Multiple -k options may be + specified. If a file called .less exists in the + user's home directory, this file is also used as a + _l_e_s_s_k_e_y file. + + -m Causes _l_e_s_s to prompt verbosely (like _m_o_r_e), with + the percent into the file. By default, _l_e_s_s + prompts with a colon. + + -M Causes _l_e_s_s to prompt even more verbosely than + _m_o_r_e_. + + -n Suppresses line numbers. The default (to use line + numbers) may cause _l_e_s_s to run more slowly in some + cases, especially with a very large input file. + Suppressing line numbers with the -n flag will + avoid this problem. Using line numbers means: the + line number will be displayed in the verbose prompt + and in the = command, and the v command will pass + the current line number to the editor (see also the + discussion of LESSEDIT in PROMPTS below). + + -N Causes a line number to be displayed at the begin- + ning of each line in the display. + + -o_f_i_l_e_n_a_m_e + Causes _l_e_s_s to copy its input to the named file as + it is being viewed. This applies only when the + input file is a pipe, not an ordinary file. If the + file already exists, _l_e_s_s will ask for confirmation + before overwriting it. + + -O_f_i_l_e_n_a_m_e + The -O option is like -o, but it will overwrite an + existing file without asking for confirmation. + + If no log file has been specified, the -o and -O + options can be used from within _l_e_s_s to specify a + log file. Without a file name, they will simply + report the name of the log file. The "s" command + is equivalent to specifying -o from within _l_e_s_s_. + + -p_p_a_t_t_e_r_n + The -p option on the command line is equivalent to + specifying +/_p_a_t_t_e_r_n; that is, it tells _l_e_s_s to + start at the first occurence of _p_a_t_t_e_r_n in the + file. + + + + + 10 + + + + + +LESS(1) LESS(1) + + + -P_p_r_o_m_p_t + Provides a way to tailor the three prompt styles to + your own preference. This option would normally be + put in the LESS environment variable, rather than + being typed in with each _l_e_s_s command. Such an + option must either be the last option in the LESS + variable, or be terminated by a dollar sign. -P + followed by a string changes the default (short) + prompt to that string. -Pm changes the medium (-m) + prompt to the string, and -PM changes the long (-M) + prompt. Also, -P= changes the message printed by + the = command to the given string. All prompt + strings consist of a sequence of letters and spe- + cial escape sequences. See the section on PROMPTS + for more details. + + -q Causes moderately "quiet" operation: the terminal + bell is not rung if an attempt is made to scroll + past the end of the file or before the beginning of + the file. If the terminal has a "visual bell", it + is used instead. The bell will be rung on certain + other errors, such as typing an invalid character. + The default is to ring the terminal bell in all + such cases. + + -Q Causes totally "quiet" operation: the terminal bell + is never rung. + + -r Causes "raw" control characters to be displayed. + The default is to display control characters using + the caret notation; for example, a control-A (octal + 001) is displayed as "^A". Warning: when the -r + flag is used, _l_e_s_s cannot keep track of the actual + appearance of the screen (since this depends on how + the screen responds to each type of control charac- + ter). Thus, various display problems may result, + such as long lines being split in the wrong place. + + -s Causes consecutive blank lines to be squeezed into + a single blank line. This is useful when viewing + _n_r_o_f_f output. + + -S Causes lines longer than the screen width to be + chopped rather than folded. That is, the remainder + of a long line is simply discarded. The default is + to fold long lines; that is, display the remainder + on the next line. + + -t_t_a_g The -t option, followed immediately by a TAG, will + edit the file containing that tag. For this to + work, there must be a file called "tags" in the + current directory, which was previously built by + the _c_t_a_g_s (1) command. This option may also be + specified from within _l_e_s_s (using the - command) as + + + + 11 + + + + + +LESS(1) LESS(1) + + + a way of examining a new file. The command ":t" is + equivalent to specifying -t from within _l_e_s_s_. + + -T_t_a_g_s_f_i_l_e + Specifies a tags file to be used instead of "tags". + + -u Causes backspaces and carriage returns to be + treated as printable characters; that is, they are + sent to the terminal when they appear in the input. + + -U Causes backspaces and carriage returns to be + treated as control characters; that is, they are + handled as specified by the -r option. + + By default, if neither -u nor -U is given, + backspaces which appear adjacent to an underscore + character are treated specially: the underlined + text is displayed using the terminal's hardware + underlining capability. Also, backspaces which + appear between two identical characters are treated + specially: the overstruck text is printed using the + terminal's hardware boldface capability. Other + backspaces are deleted, along with the preceding + character. Carriage returns immediately followed + by a newline are deleted. Other carriage returns + are handled as specified by the -r option. + + -w Causes blank lines to be used to represent lines + past the end of the file. By default, a tilde + character is used. + + -x_n Sets tab stops every _n positions. The default for + _n is 8. + + -y_n Specifies a maximum number of lines to scroll for- + ward. If it is necessary to scroll forward more + than _n lines, the screen is repainted instead. The + -c or -C option may be used to repaint from the top + of the screen if desired. By default, any forward + movement causes scrolling. + + -[z]_n Changes the default scrolling window size to _n + lines. The default is one screenful. The z and w + commands can also be used to change the window + size. The "z" may be omitted, as in "-_n" for com- + patibility with _m_o_r_e_. + + + If a command line option begins with ++, the remain- + der of that option is taken to be an initial com- + mand to _l_e_s_s_. For example, +G tells _l_e_s_s to start + at the end of the file rather than the beginning, + and +/xyz tells it to start at the first occurrence + of "xyz" in the file. As a special case, +<number> + acts like +<number>g; that is, it starts the + + + + 12 + + + + + +LESS(1) LESS(1) + + + display at the specified line number (however, see + the caveat under the "g" command above). If the + option starts with ++, the initial command applies + to every file being viewed, not just the first one. + The + command described previously may also be used + to set (or change) an initial command for every + file. + + +KKEEYY BBIINNDDIINNGGSS + You may define your own _l_e_s_s commands by using the program + _l_e_s_s_k_e_y (1) to create a file called ".less" in your home + directory. This file specifies a set of command keys and + an action associated with each key. See the _l_e_s_s_k_e_y man- + ual page for more details. + + +NNAATTIIOONNAALL CCHHAARRAACCTTEERR SSEETTSS + There are three types of characters in the input file: + + normal characters + can be displayed directly to the screen. + + control characters + should not be displayed directly, but are expected + to be found in ordinary text files (such as + backspace and tab). + + binary characters + cannot be displayed directly and are not expected + to be found in text files. + + By default, _l_e_s_s uses the ASCII character set. In the + ASCII character set, characters with values between 128 + and 255 are treated as binary. The LESSCHARSET environ- + ment variable may be used to select another character set. + If it is set to the value "latin1", the ISO 8859/1 charac- + ter set is assumed. Latin-1 is the same as ASCII, except + characters between 128 and 255 are treated as normal char- + acters. The only valid values for LESSCHARSET currently + are "ascii" and "latin1". + + In special cases, it may be desired to tailor _l_e_s_s to use + a character set other than the ones definable by LESS- + CHARSET. In this case, the environment variable LESS- + CHARDEF can be used to define a character set. It should + be set to a string where each character in the string rep- + resents one character in the character set. The character + "." is used for a normal character, "c" for control, and + "b" for binary. A decimal number may be used for repeti- + tion. For example, "bccc4b." would mean character 0 is + binary, 1, 2 and 3 are control, 4, 5, 6 and 7 are binary, + and 8 is normal. All characters after the last are taken + to be the same as the last, so characters 9 through 255 + + + + 13 + + + + + +LESS(1) LESS(1) + + + would be normal. (This is an example, and does not neces- + sarily represent any real character set.) + + Setting LESSCHARDEF to "8bcccbcc18b95.b" is the same as + setting LESSCHARSET to "ascii". Setting LESSCHARDEF to + "8bcccbcc18b95.33b." is the same as setting LESSCHARSET to + "latin1". + + Control and binary characters are displayed in blinking + mode. Each such character is displayed in caret notation + if possible (e.g. ^A for control-A). Caret notation is + used only if inverting the 0100 bit results in a normal + printable character. Otherwise, the character is dis- + played as an octal number preceded by a backslash. This + octal format can be changed by setting the LESSBINFMT + environment variable to a printf-style format string; the + default is '\%o'. The blinking mode display of control + and binary characters can be changed or disabled by pre- + ceding the LESSBINFMT format string with a "*" and one + character to select the mode: "*k" is blinking, "*d" is + bold, "*u" is underlined, and "*n" is normal (no special + display attribute). For example, if LESSBINFMT is + "*u[%x]", binary characters are displayed in underlined + hexadecimal surrounded by brackets. + + +PPRROOMMPPTTSS + The -P option allows you to tailor the prompt to your + preference. The string given to the -P option replaces + the specified prompt string. Certain characters in the + string are interpreted specially. The prompt mechanism is + rather complicated to provide flexibility, but the ordi- + nary user need not understand the details of constructing + personalized prompt strings. + + A percent sign followed by a single character is expanded + according to what the following character is: + + %b_X Replaced by the byte offset into the current input + file. The b is followed by a single character + (shown as _X above) which specifies the line whose + byte offset is to be used. If the character is a + "t", the byte offset of the top line in the display + is used, an "m" means use the middle line, a "b" + means use the bottom line, a "B" means use the line + just after the bottom line, and a "j" means use the + "target" line, as specified by the -j option. + + %B Replaced by the size of the current input file. + + %E Replaced by the name of the editor (from the EDITOR + environment variable). See the discussion of the + LESSEDIT feature below. + + + + + 14 + + + + + +LESS(1) LESS(1) + + + %f Replaced by the name of the current input file. + + %i Replaced by the index of the current file in the + list of input files. + + %l_X Replaced by the line number of a line in the input + file. The line to be used is determined by the _X, + as with the %b option. + + %L Replaced by the line number of the last line in the + input file. + + %m Replaced by the total number of input files. + + %p_X Replaced by the percent into the current input + file. The line used is determined by the _X as with + the %b option. + + %s Same as %B. + + %t Causes any trailing spaces to be removed. Usually + used at the end of the string, but may appear any- + where. + + %x Replaced by the name of the next input file in the + list. + + If any item is unknown (for example, the file size if + input is a pipe), a question mark is printed instead. + + The format of the prompt string can be changed depending + on certain conditions. A question mark followed by a sin- + gle character acts like an "IF": depending on the follow- + ing character, a condition is evaluated. If the condition + is true, any characters following the question mark and + condition character, up to a period, are included in the + prompt. If the condition is false, such characters are + not included. A colon appearing between the question mark + and the period can be used to establish an "ELSE": any + characters between the colon and the period are included + in the string if and only if the IF condition is false. + Condition characters (which follow a question mark) may + be: + + ?a True if any characters have been included in the + prompt so far. + + ?b_X True if the byte offset of the specified line is + known. + + ?B True if the size of current input file is known. + + ?e True if at end-of-file. + + + + + 15 + + + + + +LESS(1) LESS(1) + + + ?f True if there is an input filename (that is, if + input is not a pipe). + + ?l_X True if the line number of the specified line is + known. + + ?L True if the line number of the last line in the + file is known. + + ?m True if there is more than one input file. + + ?n True if this is the first prompt in a new input + file. + + ?p_X True if the percent into the current input file of + the specified line is known. + + ?s Same as "?B". + + ?x True if there is a next input file (that is, if the + current input file is not the last one). + + Any characters other than the special ones (question mark, + colon, period, percent, and backslash) become literally + part of the prompt. Any of the special characters may be + included in the prompt literally by preceding it with a + backslash. + + Some examples: + + ?f%f:Standard input. + + This prompt prints the filename, if known; otherwise the + string "Standard input". + + ?f%f .?ltLine %lt:?pt%pt\%:?btByte %bt:-... + + This prompt would print the filename, if known. The file- + name is followed by the line number, if known, otherwise + the percent if known, otherwise the byte offset if known. + Otherwise, a dash is printed. Notice how each question + mark has a matching period, and how the % after the %pt is + included literally by escaping it with a backslash. + + ?n?f%f .?m(file %i of %m) ..?e(END) ?x- Next\: %x..%t + + This prints the filename if this is the first prompt in a + file, followed by the "file N of N" message if there is + more than one input file. Then, if we are at end-of-file, + the string "(END)" is printed followed by the name of the + next file, if there is one. Finally, any trailing spaces + are truncated. This is the default prompt. For refer- + ence, here are the defaults for the other two prompts (-m + and -M respectively). Each is broken into two lines here + + + + 16 + + + + + +LESS(1) LESS(1) + + + for readability only. + + ?n?f%f .?m(file %i of %m) ..?e(END) ?x- Next\: %x.: + ?pB%pB\%:byte %bB?s/%s...%t + + ?f%f .?n?m(file %i of %m) ..?ltline %lt?L/%L. :byte %bB?s/%s. . + ?e(END) ?x- Next\: %x.:?pB%pB\%..%t + + And here is the default message produced by the = command: + + ?f%f .?m(file %i of %m) .?ltline %lt?L/%L. . + byte %bB?s/%s. ?e(END) :?pB%pB\%..%t + + The prompt expansion features are also used for another + purpose: if an environment variable LESSEDIT is defined, + it is used as the command to be executed when the v com- + mand is invoked. The LESSEDIT string is expanded in the + same way as the prompt strings. The default value for + LESSEDIT is: + + %E ?lm+%lm. %f + + Note that this expands to the editor name, followed by a + + and the line number, followed by the file name. If your + editor does not accept the "+linenumber" syntax, or has + other differences in invocation syntax, the LESSEDIT vari- + able can be changed to modify this default. + + +EENNVVIIRROONNMMEENNTT VVAARRIIAABBLLEESS + COLUMNS + Sets the number of columns on the screen. Takes + precedence over the number of columns specified by + the TERM variable. + + EDITOR The name of the editor (used for the v command). + + HOME Name of the user's home directory (used to find a + .less file). + + LESS Flags which are passed to _l_e_s_s automatically. + + LESSBINFMT + Format for displaying non-printable, non-control + characters. + + LESSCHARDEF + Defines a character set. + + LESSCHARSET + Selects a predefined character set. + + LESSEDIT + Editor prototype string (used for the v command). + + + + 17 + + + + + +LESS(1) LESS(1) + + + See discussion under PROMPTS. + + LESSHELP + Name of the help file. + + LINES Sets the number of lines on the screen. Takes + precedence over the number of lines specified by + the TERM variable. + + SHELL The shell used to execute the ! command, as well as + to expand filenames. + + TERM The type of terminal on which _l_e_s_s is being run. + + +SSEEEE AALLSSOO + lesskey(1) + + +WWAARRNNIINNGGSS + The = command and prompts (unless changed by -P) report + the line number of the line at the top of the screen, but + the byte and percent of the line at the bottom of the + screen. + + If the :e command is used to name more than one file, and + one of the named files has been viewed previously, the new + files may be entered into the list in an unexpected order. + + The handling of national character sets is nonstandard as + well as insufficient for multibyte characters. It will + probably change in a later release. + + + + + + + + + + + + + + + + + + + + + + + + + + 18 + +