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LESS(l) UNIX Programmer's Manual LESS(l) NAME less - opposite of more SYNOPSIS less [-cdepstwmMqQuU] [-h_n] [-b[fp]_n] [-x_n] [-[z]_n] [+_c_m_d] [_n_a_m_e] ... DESCRIPTION _L_e_s_s is a program similar to _m_o_r_e(1), but which allows back- wards 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 fas- ter than text editors like _v_i(1). _L_e_s_s uses termcap, 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 preceeded by a decimal number, called N in the descriptions below. The number is used by some commands, as indicated. COMMANDS h Help: display a summary of these commands. If you for- get all the other commands, remember this one. SPACE Scroll forward N lines, default one window (see option -z below). If N is more than the screen size, only one screenful is displayed. f Same as SPACE. b Scroll backward N lines, default one window (see option -z below). If N is more than the screen size, only one screenful is displayed. RETURN Scroll forward N lines, default 1. If N is more than the screen size, the entire N lines are displayed. e Same as RETURN. j Also the same as RETURN. y Scroll backward N lines, default 1. If N is more than the screen size, the entire N lines are displayed. k Same as y. d Scroll forward N lines, default 10. If N is specified, it becomes the new default for all d and u commands. Printed 8/13/86 1 LESS(l) UNIX Programmer's Manual LESS(l) u Scroll backward N lines, default 10. If N is speci- fied, it becomes the new default for all d and u com- mands. r Repaint the screen. R Repaint the screen, discarding any buffered input. Useful if the file is changing while it is being viewed. g Go to line N in the file, default 1 (beginning of file). (Warning: this may be slow if N is large.) G Go to line N in the file, default the end of the file. (Warning: this may be slow if standard input, rather than a file, is being read.) p Go to a position N percent into the file. N should be between 0 and 100. (This is possible 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.) % Same as p. m_l Followed by any lowercase letter, _l, marks the current position with that letter. '_l Followed by any lowercase letter, _l, returns to the position which was previously marked with that letter. All marks are lost when a new file is examined. /pattern Search forward in the file for the N-th occurence of the _p_a_t_t_e_r_n. N defaults to 1. The _p_a_t_t_e_r_n is a regu- lar expression, as recognized by _e_d. The search starts at the second line displayed (but see the -t option, which changes this). ?pattern Search backward in the file for the N-th occurence of the _p_a_t_t_e_r_n. The search starts at the line immediately before the top line displayed. n Repeat previous search, for N-th occurence of the last _p_a_t_t_e_r_n. E [_f_i_l_e_n_a_m_e] Examine a new file. If the _f_i_l_e_n_a_m_e is missing, the "current" file (see the N and P commands below) from the list of files in the command line is re-examined. Printed 8/13/86 2 LESS(l) UNIX Programmer's Manual LESS(l) N Examine the next file (from the list of files given in the command line). If a number N is specified (not to be confused with the command N), the N-th next file is examined. P Examine the previous file. If a number N is specified, the N-th previous file is examined. = Prints the name of the file being viewed and the byte offset of the bottom line being displayed. If possi- ble, it also prints the length of the file and the per- cent of the file above the last displayed line. - Followed by one of the command line option letters (see below), this will toggle the setting of that option and print a message describing the new setting. V Prints the version number of _l_e_s_s being run. q Exits _l_e_s_s. The following two commands may or may not be valid, depend- ing on your particular installation. v Invokes an editor to edit the current file being viewed. The editor is taken from the environment vari- able EDITOR, or defaults to _v_i. ! _s_h_e_l_l-_c_o_m_m_a_n_d Invokes a shell to run the _s_h_e_l_l-_c_o_m_m_a_n_d given. OPTIONS Command line options are described below. Options are also taken from the environment variable LESS. (The environment variable is parsed before the command line, so command line options override the LESS environment variable. Options may be changed while _l_e_s_s is running via the "-" command.) For example, if you like more-style prompting, to avoid typing less -m ... each time _l_e_s_s is invoked, you might tell _c_s_h: setenv LESS m or if you use _s_h: LESS=m; export LESS -s The -s flag causes consecutive blank lines to be squeezed into a single blank line. This is useful when viewing _n_r_o_f_f output. -t Normally, forward searches start just after the top displayed line (that is, at the second displayed line). Printed 8/13/86 3 LESS(l) UNIX Programmer's Manual LESS(l) Thus forward searches include the currently displayed screen. The -t command line option causes forward searches to start just after the bottom line displayed, thus skipping the currently displayed screen. -m Normally, _l_e_s_s prompts with a colon. The -m command line option causes _l_e_s_s to prompt verbosely like _m_o_r_e, printing the file name and percent into the file. -M The -M command line option causes _l_e_s_s to prompt even more verbosely than _m_o_r_e. -q Normally, if an attempt is made to scroll past the end of the file or before the beginning of the file, the terminal bell is rung to indicate this fact. The -q command line option tells _l_e_s_s not to ring the bell at such times. If the terminal has a "visual bell", it is used instead. -Q Even if -q is given, _l_e_s_s will ring the bell on certain other errors, such as typing an invalid character. The -Q command line option tells _l_e_s_s to be quiet all the time; that is, never ring the terminal bell. If the terminal has a "visual bell", it is used instead. -e Normally the only way to exit less is via the "q" com- mand. The -e command line option tells less to automatically exit the second time it reaches end-of- file. -u If the -u command line option is given, backspaces are treated as printable characters; that is, they are sent to the terminal when they appear in the input. -U If the -U command line option is given, backspaces are printed as the two character sequence "^H". If neither -u nor -U is given, backspaces which appear adjacent to an underscore character or sequences of a character interleaved with backspaces are treated specially: the underlined or boldfaced text is displayed using the terminal's hardware capability. Note that the -v option below superceeds both -u and -U. -w Normally, _l_e_s_s uses a tilde character to represent lines past the end of the file. The -w option causes blank lines to be used instead. -d Normally, _l_e_s_s will complain if the terminal is dumb; that is, lacks some important capability, such as the ability to clear the screen or scroll backwards. The -d flag suppresses this complaint (but does not other- wise change the behavior of the program on a dumb Printed 8/13/86 4 LESS(l) UNIX Programmer's Manual LESS(l) terminal). -p Normally, _l_e_s_s will repaint the screen by scrolling from the bottom of the screen. If the -p flag is set, when _l_e_s_s needs to change the entire display, it will clear the screen and paint from the top line down. -h_n Normally, _l_e_s_s will scroll backwards when backwards movement is necessary. The -h option specifies a max- imum number of lines to scroll backwards. If it is necessary to move backwards more than this many lines, the screen is repainted in a forward direction. (If the terminal does not have the ability to scroll back- wards, -h_0 is implied.) -[z]_n When given a backwards or forwards window command, _l_e_s_s will by default scroll backwards or forwards one screenful of lines. The -z option changes the default scrolling window size to _n lines. If _n is greater than the screen size, the scrolling window size will be set to one screenful. Note that the z is optional for com- patibility with more. -x The -x command line option sets tab stops every _n posi- tions. The default for _n is 8. -b[fp]_n The -b command line option tells _l_e_s_s to use a non- standard buffer size. There are two standard (default) buffer sizes, one is used when a file is being read and the other when a pipe (standard input) is being read. The current defaults are 5 buffers for files and 12 for pipes. (Buffers are 1024 bytes.) The number _n speci- fies a different number of buffers to use. The -b may be followed by f, in which case only the file default is changed, or by p in which case only the pipe default is changed. Otherwise, both are changed. -c Normally, when data is read by _l_e_s_s, it is scanned to ensure that bit 7 (the high order bit) is turned off in each byte read, and to ensure that there are no null (zero) bytes in the data (null bytes are turned into "@" characters). If the data is known to be "clean", the -c command line option will tell _l_e_s_s to skip this checking, causing an imperceptible speed improvement. (However, if the data is not "clean", unpredicatable results may occur.) -v The -v option tells less to print non-printing charac- ters in a visible way ala _c_a_t(1). Control characters are printed as ^X (the delete character (octal 0177) is Printed 8/13/86 5 LESS(l) UNIX Programmer's Manual LESS(l) printed as ^?). Characters with the 0200 bit set are printed as M- followed by the character represented by the low order seven bits. +_c_o_m_m_a_n_d If a command line option begins with +, the remainder of that option is taken to be an initial command 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 +/_x_y_z tells it to start at the first occurence of _x_y_z in the file. As a special case, +<_n_u_m_b_e_r> acts like +<_n_u_m_b_e_r>_g; that is, it starts the 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. BUGS When used on standard input (rather than a file), you can move backwards only a finite amount, corresponding to that portion of the file which is still buffered. Printed 8/13/86 6