1.\" $OpenBSD: less.1,v 1.22 2011/05/02 11:14:11 jmc Exp $ 2.\" 3.\" Copyright (C) 2002 Mark Nudelman 4.\" 5.\" Redistribution and use in source and binary forms, with or without 6.\" modification, are permitted provided that the following conditions 7.\" are met: 8.\" 1. Redistributions of source code must retain the above copyright 9.\" notice, this list of conditions and the following disclaimer. 10.\" 2. Redistributions in binary form must reproduce the above copyright 11.\" notice in the documentation and/or other materials provided with 12.\" the distribution. 13.\" 14.\" THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY 15.\" EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 16.\" IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR 17.\" PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR BE LIABLE 18.\" FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR 19.\" CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT 20.\" OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR 21.\" BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, 22.\" WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE 23.\" OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN 24.\" IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. 25.\" 26.Dd $Mdocdate: May 2 2011 $ 27.Dt LESS 1 28.Os 29.Sh NAME 30.Nm less , more 31.Nd view files 32.Sh SYNOPSIS 33.Nm less \*(Ba more 34.Fl \&? 35.Nm less \*(Ba more 36.Fl -help 37.Nm less \*(Ba more 38.Fl V 39.Nm less \*(Ba more 40.Fl -version 41.Nm less \*(Ba more 42.Bk -words 43.Op Fl Oo Cm + Oc Ns Cm aBCcdEeFfGgIiJLMmNnQqRrSsUuVWwX~ 44.Op Fl b Ar space 45.Op Fl h Ar lines 46.Op Fl j Ar line 47.Op Fl k Ar keyfile 48.Op Fl O | o Ar logfile 49.Op Fl P Ar prompt 50.Op Fl p Ar pattern 51.Op Fl T Ar tagsfile 52.Op Fl t Ar tag 53.Op Fl x Ar tab,... 54.Op Fl y Ar lines 55.Op Fl Oo Cm z Oc Ar lines 56.Op Fl # Ar shift 57.Xo Oo Cm \&+ Ns Oo Ns Cm \&+ Ns 58.Oc Ar cmd 59.Oc 60.Xc 61.Op Fl - 62.Op Ar filename ... 63.Ek 64.\" (See the 65.\" .Sx OPTIONS 66.\" section for alternate option syntax with long option names.) 67.Sh DESCRIPTION 68.Nm 69is a program similar to the traditional 70.Xr more 1 , 71but which allows backward movement in the file as well as forward movement. 72Also, 73.Nm 74does not have to read the entire input file before starting, 75so with large input files it starts up faster than text editors like 76.Xr vi 1 . 77.Nm 78uses termcap (or terminfo on some systems), 79so it can run on a variety of terminals. 80There is even limited support for hardcopy terminals. 81(On a hardcopy terminal, lines which should be printed at the top 82of the screen are prefixed with a caret.) 83.Pp 84This version of 85.Nm 86also acts as 87.Xr more 1 88if it is called as 89.Nm more . 90In this mode, the differences are in the prompt and that 91.Nm more 92exits by default when it gets to the end of the file. 93Commands are based on both traditional 94.Nm more 95and 96.Xr vi 1 . 97Commands may be preceded by a decimal number, 98called N in the descriptions below. 99The number is used by some commands, as indicated. 100.Sh COMMANDS 101In the following descriptions, ^X means control-X. 102ESC stands for the ESCAPE key; for example ESC-v means the 103two character sequence "ESCAPE", then "v". 104.Bl -tag -width XXXX 105.It Ic h | H 106Help: display a summary of these commands. 107If you forget all the other commands, remember this one. 108.It Ic SPACE | ^V | f | ^F 109Scroll forward N lines, default one window (see option -z below). 110If N is more than the screen size, only the final screenful is displayed. 111Warning: some systems use ^V as a special literalization character. 112.It Ic z 113Like SPACE, but if N is specified, it becomes the new window size. 114.It Ic ESC-SPACE 115Like SPACE, but scrolls a full screensful, even if it reaches 116end-of-file in the process. 117.It Ic RETURN | ^N | e | ^E | j | ^J 118Scroll forward N lines, default 1. 119The entire N lines are displayed, even if N is more than the screen size. 120.It Ic d | ^D 121Scroll forward N lines, default one half of the screen size. 122If N is specified, it becomes the new default for subsequent d and u commands. 123.It Ic b | ^B | ESC-v 124Scroll backward N lines, default one window (see option -z below). 125If N is more than the screen size, only the final screenful is displayed. 126.It Ic w 127Like ESC-v, but if N is specified, it becomes the new window size. 128.It Ic y | ^Y | ^P | k | ^K 129Scroll backward N lines, default 1. 130The entire N lines are displayed, even if N is more than the screen size. 131Warning: some systems use ^Y as a special job control character. 132.It Ic u | ^U 133Scroll backward N lines, default one half of the screen size. 134If N is specified, it becomes the new default for subsequent d and u commands. 135.It Ic ESC-) | RIGHTARROW 136Scroll horizontally right N characters, default half the screen width 137(see the -# option). 138If a number N is specified, it becomes the default for future 139RIGHTARROW and LEFTARROW commands. 140While the text is scrolled, it acts as though the -S option (chop lines) 141were in effect. 142.It Ic ESC-( | LEFTARROW 143Scroll horizontally left N 144characters, default half the screen width (see the -# option). 145If a number N is specified, it becomes the default for future 146RIGHTARROW and LEFTARROW commands. 147.It Ic r | ^R | ^L 148Repaint the screen. 149.It Ic R 150Repaint the screen, discarding any buffered input. 151Useful if the file is changing while it is being viewed. 152.It Ic F 153Scroll forward, and keep trying to read when the end of file is reached. 154Normally this command would be used when already at the end of the file. 155It is a way to monitor the tail of a file which is growing 156while it is being viewed. 157(The behavior is similar to the "tail -f" command.) 158.It Ic g | < | ESC-< 159Go to line N in the file, default 1 (beginning of file). 160(Warning: this may be slow if N is large.) 161.It Ic G | > | ESC-> 162Go to line N in the file, default the end of the file. 163(Warning: this may be slow if N is large, 164or if N is not specified and standard input, rather than a file, 165is being read.) 166.It Ic p | % 167Go to a position N percent into the file. 168N should be between 0 and 100. 169.It Ic { 170If a left curly bracket appears in the top line displayed 171on the screen, the { command will go to the matching right curly bracket. 172The matching right curly bracket is positioned on the bottom 173line of the screen. 174If there is more than one left curly bracket on the top line, a number N 175may be used to specify the N-th bracket on the line. 176.It Ic } 177If a right curly bracket appears in the bottom line displayed on the screen, 178the } command will go to the matching left curly bracket. 179The matching left curly bracket is positioned on the top 180line of the screen. 181If there is more than one right curly bracket on the top line, 182a number N may be used to specify the N-th bracket on the line. 183.It Ic \&( 184Like {, but applies to parentheses rather than curly brackets. 185.It Ic \&) 186Like }, but applies to parentheses rather than curly brackets. 187.It Ic \&[ 188Like {, but applies to square brackets rather than curly brackets. 189.It Ic \&] 190Like }, but applies to square brackets rather than curly brackets. 191.It Ic ESC-^F 192Followed by two characters, acts like {, 193but uses the two characters as open and close brackets, respectively. 194For example, "ESC ^F < >" could be used to 195go forward to the > which matches the < in the top displayed line. 196.It Ic ESC-^B 197Followed by two characters, acts like }, 198but uses the two characters as open and close brackets, respectively. 199For example, "ESC ^B < >" could be used to 200go backward to the < which matches the > in the bottom displayed line. 201.It Ic m 202Followed by any lowercase letter, marks the current position with that letter. 203.It Ic ' 204(Single quote.) 205Followed by any lowercase letter, returns to the position which 206was previously marked with that letter. 207Followed by another single quote, returns to the position at 208which the last "large" movement command was executed. 209Followed by a ^ or $, jumps to the beginning or end of the file respectively. 210Marks are preserved when a new file is examined, 211so the ' command can be used to switch between input files. 212.It Ic ^X^X 213Same as single quote. 214.It Ic /pattern 215Search forward in the file for the N-th line containing the pattern. 216N defaults to 1. 217The pattern is a regular expression, as recognized by 218.Xr ed 1 . 219The search starts at the second line displayed 220(but see the -a and -j options, which change this). 221.Pp 222Certain characters are special if entered at the beginning of the pattern; 223they modify the type of search rather than become part of the pattern: 224.Bl -tag -width Ds 225.It Ic ^N | \&! 226Search for lines which do NOT match the pattern. 227.It Ic ^E | * 228Search multiple files. 229That is, if the search reaches the END of the current file 230without finding a match, 231the search continues in the next file in the command line list. 232.It Ic ^F | @ 233Begin the search at the first line of the FIRST file 234in the command line list, 235regardless of what is currently displayed on the screen 236or the settings of the -a or -j options. 237.It Ic ^K 238Highlight any text which matches the pattern on the current screen, 239but don't move to the first match (KEEP current position). 240.It Ic ^R 241Don't interpret regular expression metacharacters; 242that is, do a simple textual comparison. 243.El 244.It Ic ?pattern 245Search backward in the file for the N-th line containing the pattern. 246The search starts at the line immediately before the top line displayed. 247.Pp 248Certain characters are special, as in the / command: 249.Bl -tag -width Ds 250.It Ic ^N | \&! 251Search for lines which do NOT match the pattern. 252.It Ic ^E | * 253Search multiple files. 254That is, if the search reaches the beginning of the current file 255without finding a match, 256the search continues in the previous file in the command line list. 257.It Ic ^F | @ 258Begin the search at the last line of the last file 259in the command line list, 260regardless of what is currently displayed on the screen 261or the settings of the -a or -j options. 262.It Ic ^K 263As in forward searches. 264.It Ic ^R 265As in forward searches. 266.El 267.It Ic ESC-/pattern 268Same as "/*". 269.It Ic ESC-?pattern 270Same as "?*". 271.It Ic n 272Repeat previous search, for N-th line containing the last pattern. 273If the previous search was modified by ^N, the search is made for the 274N-th line NOT containing the pattern. 275If the previous search was modified by ^E, the search continues 276in the next (or previous) file if not satisfied in the current file. 277If the previous search was modified by ^R, the search is done 278without using regular expressions. 279There is no effect if the previous search was modified by ^F or ^K. 280.It Ic N 281Repeat previous search, but in the reverse direction. 282.It Ic ESC-n 283Repeat previous search, but crossing file boundaries. 284The effect is as if the previous search were modified by *. 285.It Ic ESC-N 286Repeat previous search, but in the reverse direction 287and crossing file boundaries. 288.It Ic ESC-u 289Undo search highlighting. 290Turn off highlighting of strings matching the current search pattern. 291If highlighting is already off because of a previous ESC-u command, 292turn highlighting back on. 293Any search command will also turn highlighting back on. 294(Highlighting can also be disabled by toggling the -G option; 295in that case search commands do not turn highlighting back on.) 296.It Ic :e Op Ar filename 297Examine a new file. 298If the filename is missing, the "current" file (see the :n and :p commands 299below) from the list of files in the command line is re-examined. 300A percent sign (%) in the filename is replaced by the name of the 301current file. 302A pound sign (#) is replaced by the name of the previously examined file. 303However, two consecutive percent signs are simply 304replaced with a single percent sign. 305This allows you to enter a filename that contains a percent sign 306in the name. 307Similarly, two consecutive pound signs are replaced with a single pound sign. 308The filename is inserted into the command line list of files 309so that it can be seen by subsequent :n and :p commands. 310If the filename consists of several files, they are all inserted into 311the list of files and the first one is examined. 312If the filename contains one or more spaces, 313the entire filename should be enclosed in double quotes 314(also see the -" option). 315.It Ic ^X^V | E 316Same as :e. 317Warning: some systems use ^V as a special literalization character. 318On such systems, you may not be able to use ^V. 319.It Ic :n 320Examine the next file (from the list of files given in the command line). 321If a number N is specified, the N-th next file is examined. 322.It Ic :p 323Examine the previous file in the command line list. 324If a number N is specified, the N-th previous file is examined. 325.It Ic :t 326Go to the specified tag. 327.It Ic :x 328Examine the first file in the command line list. 329If a number N is specified, the N-th file in the list is examined. 330.It Ic :d 331Remove the current file from the list of files. 332.It Ic t 333Go to the next tag, if there were more than one matches for the current tag. 334See the \-t option for more details about tags. 335.It Ic T 336Go to the previous tag, if there were more than one matches for the current tag. 337.It Ic = | ^G | :f 338Prints some information about the file being viewed, including its name 339and the line number and byte offset of the bottom line being displayed. 340If possible, it also prints the length of the file, 341the number of lines in the file 342and the percent of the file above the last displayed line. 343.It Ic \- 344Followed by one of the command line option letters (see 345.Sx OPTIONS 346below), 347this will change the setting of that option 348and print a message describing the new setting. 349If a ^P (CONTROL-P) is entered immediately after the dash, 350the setting of the option is changed but no message is printed. 351If the option letter has a numeric value (such as -b or -h), 352or a string value (such as -P or -t), 353a new value may be entered after the option letter. 354If no new value is entered, a message describing 355the current setting is printed and nothing is changed. 356.It Ic \-\- 357Like the \- command, but takes a long option name (see 358.Sx OPTIONS 359below) 360rather than a single option letter. 361You must press RETURN after typing the option name. 362A ^P immediately after the second dash suppresses printing of a 363message describing the new setting, as in the \- command. 364.It Ic \-+ 365Followed by one of the command line option letters this will reset the 366option to its default setting and print a message describing the new setting. 367(The "\-+X" command does the same thing as "\-+X" on the command line.) 368This does not work for string-valued options. 369.It Ic \-\-+ 370Like the \-+ command, but takes a long option name 371rather than a single option letter. 372.It Ic \-! 373Followed by one of the command line option letters, this will reset the 374option to the "opposite" of its default setting and print a message 375describing the new setting. 376This does not work for numeric or string-valued options. 377.It Ic \-\-! 378Like the \-! command, but takes a long option name 379rather than a single option letter. 380.It Ic _ 381(Underscore.) 382Followed by one of the command line option letters, 383this will print a message describing the current setting of that option. 384The setting of the option is not changed. 385.It Ic __ 386(Double underscore.) 387Like the _ (underscore) command, but takes a long option name 388rather than a single option letter. 389You must press RETURN after typing the option name. 390.It Ic +cmd 391Causes the specified cmd to be executed each time a new file is examined. 392For example, +G causes 393.Nm 394to initially display each file starting at the end rather than the beginning. 395.It Ic V 396Prints the version number of 397.Nm 398being run. 399.It Ic q | Q | :q | :Q | ZZ 400Exits 401.Nm less . 402.El 403.Pp 404The following 405four 406commands may or may not be valid, depending on your particular installation. 407.Bl -tag -width XXXX 408.It Ic v 409Invokes an editor to edit the current file being viewed. 410The editor is taken from the environment variable 411.Ev VISUAL , 412if defined, 413or 414.Ev EDITOR 415if 416.Ev VISUAL 417is not defined, 418or defaults to "vi" if neither 419.Ev VISUAL 420nor 421.Ev EDITOR 422is defined. 423See also the discussion of LESSEDIT under the section on 424.Sx PROMPTS 425below. 426.It Ic \&! Ar shell-command 427Invokes a shell to run the shell-command given. 428A percent sign (%) in the command is replaced by the name of the current file. 429A pound sign (#) is replaced by the name of the previously examined file. 430"!!" repeats the last shell command. 431"!" with no shell command simply invokes a shell. 432The shell is taken from the environment variable 433.Ev SHELL , 434or defaults to "sh". 435.\" On MS-DOS and OS/2 systems, the shell is the normal command processor. 436.It Ic | <m> Ar shell-command 437<m> represents any mark letter. 438Pipes a section of the input file to the given shell command. 439The section of the file to be piped is between the first line on 440the current screen and the position marked by the letter. 441<m> may also be ^ or $ to indicate beginning or end of file respectively. 442If <m> is . or newline, the current screen is piped. 443.It Ic s Ar filename 444Save the input to a file. 445This only works if the input is a pipe, not an ordinary file. 446.El 447.Sh OPTIONS 448Command line options are described below. 449Most options may be changed while 450.Nm 451is running, via the "\-" command. 452.Pp 453Most options may be given in one of two forms: 454either a dash followed by a single letter, or two dashes followed by a 455long option name. 456A long option name may be abbreviated as long as the abbreviation is 457unambiguous. 458For example, --quit-at-eof may be abbreviated --quit, but not 459--qui, since both --quit-at-eof and --quiet begin with --qui. 460Some long option names are in uppercase, such as --QUIT-AT-EOF, as 461distinct from --quit-at-eof. 462Such option names need only have their first letter capitalized; 463the remainder of the name may be in either case. 464For example, --Quit-at-eof is equivalent to --QUIT-AT-EOF. 465.Pp 466Options are also taken from the environment variable 467.Ev LESS 468if the command is 469.Nm less , 470or from the environment variable 471.Ev MORE 472if the command is 473.Nm more . 474For example, to avoid typing "less -options ..." each time 475.Nm 476is invoked, you might tell 477.Xr csh 1 : 478.Pp 479.Dl setenv LESS "-options" 480.Pp 481or if you use 482.Xr sh 1 : 483.Pp 484.Dl LESS="-options"; export LESS 485.Pp 486.\" On MS-DOS, you don't need the quotes, but you should replace any 487.\" percent signs in the options string by double percent signs. 488.\" .Pp 489The environment variable is parsed before the command line, 490so command line options override the 491.Ev LESS 492environment variable. 493If an option appears in the 494.Ev LESS 495variable, it can be reset to its default value on the command line by 496beginning the command line option with "\-+". 497.Pp 498For options like -P which take a following string, 499a dollar sign ($) must be used to signal the end of the string. 500For example, to separate a prompt value from any other options 501with dollar sign between them: 502.Pp 503.Dl LESS="-Ps--More--$-C -e" 504.Bl -tag -width XXXX 505.It Fl \&? | -help 506This option displays a summary of the commands accepted by 507.Nm 508(the same as the h command). 509(Depending on how your shell interprets the question mark, 510it may be necessary to quote the question mark, thus: "-\e?".) 511.It Fl a | -search-skip-screen 512Causes searches to start after the last line displayed on the screen, 513thus skipping all lines displayed on the screen. 514By default, searches start at the second line on the screen 515(or after the last found line; see the -j option). 516.It Fl B | -auto-buffers 517By default, when data is read from a pipe, 518buffers are allocated automatically as needed. 519If a large amount of data is read from the pipe, this can cause 520a large amount of memory to be allocated. 521The -B option disables this automatic allocation of buffers for pipes, 522so that only 64K (or the amount of space specified by the -b option) 523is used for the pipe. 524Warning: use of -B can result in erroneous display, since only the 525most recently viewed part of the file is kept in memory; 526any earlier data is lost. 527.It Xo 528.Fl b Ns Ar n | 529.Fl -buffers Ns = Ns Ar n 530.Xc 531Specifies the amount of buffer space 532.Nm 533will use for each file, in units of kilobytes (1024 bytes). 534By default 64K of buffer space is used for each file 535(unless the file is a pipe; see the -B option). 536The -b option specifies instead that n kilobytes of 537buffer space should be used for each file. 538If n is -1, buffer space is unlimited; that is, 539the entire file is read into memory. 540.It Fl C | -CLEAR-SCREEN 541The -C option is like -c, but the screen is cleared before it is repainted. 542.It Fl c | -clear-screen 543Causes full screen repaints to be painted from the top line down. 544By default, 545full screen repaints are done by scrolling from the bottom of the screen. 546.It Fl d | -dumb No (less only) 547The -d option suppresses the error message 548normally displayed if the terminal is dumb; 549that is, lacks some important capability, 550such as the ability to clear the screen or scroll backward. 551The -d option does not otherwise change the behavior of 552.Nm 553on a dumb terminal. 554This option is on by default when invoked as 555.Nm more . 556.It Fl d No (more only) 557The -d option causes the default prompt to include the 558basic directions ``[Press space to continue, 'q' to quit.]''. 559The -d option also causes the message ``[Press 'h' for instructions.]'' to be 560displayed when an invalid command is entered (normally, the bell is rung). 561This option is useful in environments where users may not be experienced 562with pagers. 563.\" .It Fl Dxcolor or --color=xcolor" 564.\" [MS-DOS only] 565.\" Sets the color of the text displayed. 566.\" x is a single character which selects the type of text whose color is 567.\" being set: n=normal, s=standout, d=bold, u=underlined, k=blink. 568.\" color is a pair of numbers separated by a period. 569.\" The first number selects the foreground color and the second selects 570.\" the background color of the text. 571.\" A single number N is the same as N.0. 572.It Fl E | -QUIT-AT-EOF 573Causes 574.Nm 575to automatically exit the first time it reaches end-of-file. 576.It Fl e | -quit-at-eof 577Causes 578.Nm 579to automatically exit the second time it reaches end-of-file. 580By default, the only way to exit 581.Nm 582is via the "q" command. 583.It Fl F | -quit-if-one-screen 584Causes 585.Nm 586to automatically exit if the entire file can be displayed on the first screen. 587.It Fl f | -force 588Forces non-regular files to be opened. 589(A non-regular file is a directory or a device special file.) 590Also suppresses the warning message when a binary file is opened. 591By default, 592.Nm 593will refuse to open non-regular files. 594.It Fl G | -HILITE-SEARCH 595The -G option suppresses all highlighting of strings found by search commands. 596.It Fl g | -hilite-search 597Normally, 598.Nm 599will highlight ALL strings which match the last search command. 600The -g option changes this behavior to highlight only the particular string 601which was found by the last search command. 602This can cause 603.Nm 604to run somewhat faster than the default. 605.It Xo 606.Fl h Ns Ar n | 607.Fl -max-back-scroll Ns = Ns Ar n 608.Xc 609Specifies a maximum number of lines to scroll backward. 610If it is necessary to scroll backward more than n lines, 611the screen is repainted in a forward direction instead. 612(If the terminal does not have the ability to scroll backward, -h0 is implied.) 613.It Fl I | -IGNORE-CASE 614Like -i, but searches ignore case even if the pattern contains uppercase 615letters. 616.It Fl i | -ignore-case 617Causes searches to ignore case; that is, 618uppercase and lowercase are considered identical. 619This option is ignored if any uppercase letters appear in the search pattern; 620in other words, 621if a pattern contains uppercase letters, then that search does not ignore case. 622.It Fl J | -status-column 623Displays a status column at the left edge of the screen. 624The status column shows the lines that matched the current search. 625The status column is also used if the -w or -W option is in effect. 626.It Xo 627.Fl j Ns Ar n | 628.Fl -jump-target Ns = Ns Ar n 629.Xc 630Specifies a line on the screen where the "target" line is to be positioned. 631A target line is the object of a text search, 632tag search, jump to a line number, 633jump to a file percentage, or jump to a marked position. 634The screen line is specified by a number: the top line on the screen 635is 1, the next is 2, and so on. 636The number may be negative to specify a line relative to the bottom 637of the screen: the bottom line on the screen is -1, the second 638to the bottom is -2, and so on. 639If the -j option is used, searches begin at the line immediately 640after the target line. 641For example, if "-j4" is used, the target line is the 642fourth line on the screen, so searches begin at the fifth line on the screen. 643.It Xo 644.Fl k Ns Ar filename | 645.Fl -lesskey-file Ns = Ns Ar filename 646.Xc 647Causes 648.Nm 649to open and interpret the named file as a 650.Xr lesskey 1 651file. 652Multiple -k options may be specified. 653If the 654.Ev LESSKEY 655or 656.Ev LESSKEY_SYSTEM 657environment variable is set, or if a lesskey file is found in a standard place 658(see 659.Sx KEY BINDINGS ) , 660it is also used as a lesskey file. 661.It Fl L | -no-lessopen 662Ignore the 663.Ev LESSOPEN 664environment variable (see the 665.Sx INPUT PREPROCESSOR 666section below). 667This option can be set from within 668.Nm less , 669but it will apply only to files opened subsequently, not to the 670file which is currently open. 671When invoked as 672.Nm more , 673the 674.Ev LESSOPEN 675environment variable is ignored by default. 676.It Fl M | -LONG-PROMPT 677Causes 678.Nm 679to prompt even more verbosely than 680.Nm more . 681.It Fl m | -long-prompt 682Causes 683.Nm 684to prompt verbosely (like more), with the percent into the file. 685By default, 686.Nm 687prompts with a colon. 688.It Fl N | -LINE-NUMBERS 689Causes a line number to be displayed at the beginning of each line in the 690display. 691.It Fl n | -line-numbers 692Suppresses line numbers. 693The default (to use line numbers) may cause 694.Nm 695to run more slowly in some cases, especially with a very large input file. 696Suppressing line numbers with the -n option will avoid this problem. 697Using line numbers means: the line number will be displayed in the verbose 698prompt and in the = command, and the v command will pass the current line 699number to the editor (see also the discussion of LESSEDIT in 700.Sx PROMPTS 701below). 702.It Xo 703.Fl O Ns Ar filename | 704.Fl -LOG-FILE Ns = Ns Ar filename 705.Xc 706The -O option is like -o, but it will overwrite an existing 707file without asking for confirmation. 708.Pp 709If no log file has been specified, 710the -o and -O options can be used from within 711.Nm 712to specify a log file. 713Without a file name, they will simply report the name of the log file. 714The "s" command is equivalent to specifying -o from within 715.Nm less . 716.It Xo 717.Fl o Ns Ar filename | 718.Fl -log-file Ns = Ns Ar filename 719.Xc 720Causes 721.Nm 722to copy its input to the named file as it is being viewed. 723This applies only when the input file is a pipe, not an ordinary file. 724If the file already exists, 725.Nm 726will ask for confirmation before overwriting it. 727.It Xo 728.Fl P Ns Ar prompt | 729.Fl -prompt Ns = Ns Ar prompt 730.Xc 731Provides a way to tailor the three prompt styles to your own preference. 732This option would normally be put in the 733.Ev LESS 734environment variable, rather than being typed in with each 735.Nm 736command. 737Such an option must either be the last option in the 738.Ev LESS 739variable, or be terminated by a dollar sign. 740-Ps followed by a string changes the default (short) prompt to that string. 741-Pm changes the medium (-m) prompt. 742-PM changes the long (-M) prompt. 743-Ph changes the prompt for the help screen. 744-P= changes the message printed by the = command. 745-Pw changes the message printed while waiting for data (in the F command). 746All prompt strings consist of a sequence of letters and special escape 747sequences. 748See the section on 749.Sx PROMPTS 750for more details. 751.It Xo 752.Fl p Ns Ar pattern | 753.Fl -pattern Ns = Ns Ar pattern 754.Xc 755The -p option on the command line is equivalent to specifying +/pattern; 756that is, it tells 757.Nm 758to start at the first occurrence of pattern in the file. 759.It Fl Q | -QUIET | -SILENT 760Causes totally "quiet" operation: the terminal bell is never rung. 761.It Fl q | -quiet | -silent 762Causes moderately "quiet" operation: 763the terminal bell is not rung if an attempt is made to scroll past the end 764of the file or before the beginning of the file. 765If the terminal has a "visual bell", it is used instead. 766The bell will be rung on certain other errors, 767such as typing an invalid character. 768The default is to ring the terminal bell in all such cases. 769.It Fl R | -RAW-CONTROL-CHARS 770Like -r, but tries to keep track of the screen appearance where possible. 771This works only if the input consists of normal text and possibly some 772ANSI "color" escape sequences, which are sequences of the form: 773.Pp 774.Dl ESC \&[ ... m 775.Pp 776where the "..." is zero or more characters other than "m". 777For the purpose of keeping track of screen appearance, 778all control characters and all ANSI color escape sequences are 779assumed to not move the cursor. 780You can make 781.Nm 782think that characters other than "m" can end ANSI color escape sequences 783by setting the environment variable 784.Ev LESSANSIENDCHARS 785to the list of characters which can end a color escape sequence. 786.It Fl r | -raw-control-chars 787Causes "raw" control characters to be displayed. 788The default is to display control characters using the caret notation; 789for example, a control-A (octal 001) is displayed as "^A". 790Warning: when the -r option is used, 791.Nm 792cannot keep track of the actual appearance of the screen 793(since this depends on how the screen responds to 794each type of control character). 795Thus, various display problems may result, 796such as long lines being split in the wrong place. 797.It Fl S | -chop-long-lines 798Causes lines longer than the screen width to be chopped rather than folded. 799That is, the portion of a long line that does not fit in 800the screen width is not shown. 801The default is to fold long lines; that is, display the remainder 802on the next line. 803.It Fl s | -squeeze-blank-lines 804Causes consecutive blank lines to be squeezed into a single blank line. 805.It Xo 806.Fl T Ns Ar tagsfile | 807.Fl -tag-file Ns = Ns Ar tagsfile 808.Xc 809Specifies a tags file to be used instead of "tags". 810.It Xo 811.Fl t Ns Ar tag | 812.Fl -tag Ns = Ns Ar tag 813.Xc 814The -t option, followed immediately by a TAG, 815will edit the file containing that tag. 816For this to work, tag information must be available; 817for example, there may be a file in the current directory called "tags", 818which was previously built by 819.Xr ctags 1 820or an equivalent command. 821If the environment variable 822.Ev LESSGLOBALTAGS 823is set, it is taken to be the name of a command compatible with 824.Xr global , 825and that command is executed to find the tag. 826(See http://www.gnu.org/software/global/global.html). 827The -t option may also be specified from within 828.Nm 829(using the \- command) as a way of examining a new file. 830The command ":t" is equivalent to specifying -t from within 831.Nm less . 832.It Fl U | -UNDERLINE-SPECIAL 833Causes backspaces, tabs and carriage returns to be 834treated as control characters; 835that is, they are handled as specified by the -r option. 836.Pp 837By default, if neither -u nor -U is given, backspaces which appear adjacent 838to an underscore character are treated specially: 839the underlined text is displayed 840using the terminal's hardware underlining capability. 841Also, backspaces which appear between two identical characters 842are treated specially: 843the overstruck text is printed 844using the terminal's hardware boldface capability. 845Other backspaces are deleted, along with the preceding character. 846Carriage returns immediately followed by a newline are deleted. 847Other carriage returns are handled as specified by the -r option. 848Text which is overstruck or underlined can be searched for 849if neither -u nor -U is in effect. 850.It Fl u | -underline-special 851Causes backspaces and carriage returns to be treated as printable characters; 852that is, they are sent to the terminal when they appear in the input. 853.It Fl V | -version 854Displays the version number of 855.Nm less . 856.It Fl W | -HILITE-UNREAD 857Like -w, but temporarily highlights the first new line after any 858forward movement command larger than one line. 859.It Fl w | -hilite-unread 860Temporarily highlights the first "new" line after a forward movement 861of a full page. 862The first "new" line is the line immediately following the line previously 863at the bottom of the screen. 864Also highlights the target line after a g or p command. 865The highlight is removed at the next command which causes movement. 866The entire line is highlighted, unless the -J option is in effect, 867in which case only the status column is highlighted. 868.It Fl X | -no-init 869Disables sending the termcap initialization and deinitialization strings 870to the terminal. 871This is sometimes desirable if the deinitialization string does 872something unnecessary, like clearing the screen. 873.It Xo 874.Fl x Ns Ar n,... | 875.Fl -tabs Ns = Ns Ar n,... 876.Xc 877Sets tab stops. 878If only one n is specified, tab stops are set at multiples of n. 879If multiple values separated by commas are specified, tab stops are set at 880those positions, and then continue with the same spacing as the last two. 881For example, -x9,17 will set tabs at positions 9, 17, 25, 33, etc. 882The default for n is 8. 883.It Xo 884.Fl y Ns Ar n | 885.Fl -max-forw-scroll Ns = Ns Ar n 886.Xc 887Specifies a maximum number of lines to scroll forward. 888If it is necessary to scroll forward more than n lines, 889the screen is repainted instead. 890The -c or -C option may be used to repaint from the top of 891the screen if desired. 892By default, any forward movement causes scrolling. 893.It Xo 894.Fl Oo Cm z Oc Ns Ar n | 895.Fl -window Ns = Ns Ar n 896.Xc 897Changes the default scrolling window size to n lines. 898The default is one screenful. 899The z and w commands can also be used to change the window size. 900The "z" may be omitted for compatibility with 901.Nm more . 902If the number 903.Ar n 904is negative, it indicates 905.Ar n 906lines less than the current screen size. 907For example, if the screen is 24 lines, -z-4 sets the 908scrolling window to 20 lines. 909If the screen is resized to 40 lines, 910the scrolling window automatically changes to 36 lines. 911.It Fl -no-keypad 912Disables sending the keypad initialization and deinitialization strings 913to the terminal. 914This is sometimes useful if the keypad strings make the numeric 915keypad behave in an undesirable manner. 916.It Xo 917.Ar -cc | 918.Fl -quotes Ns = Ns Ar cc 919.Xc 920Changes the filename quoting character. 921This may be necessary if you are trying to name a file 922which contains both spaces and quote characters. 923Followed by a single character, this changes the quote character to that 924character. 925Filenames containing a space should then be surrounded by that character 926rather than by double quotes. 927Followed by two characters, changes the open quote to the first character, 928and the close quote to the second character. 929Filenames containing a space should then be preceded by the open quote 930character and followed by the close quote character. 931Note that even after the quote characters are changed, this option 932remains -" (a dash followed by a double quote). 933.It Fl ~ | -tilde 934Normally lines after end of file are displayed as a single tilde (~). 935This option causes lines after end of file to be displayed as blank lines. 936.It Fl # | -shift 937Specifies the default number of positions to scroll horizontally 938in the RIGHTARROW and LEFTARROW commands. 939If the number specified is zero, it sets the default number of 940positions to one half of the screen width. 941.It Fl - 942A command line argument of "--" marks the end of option arguments. 943Any arguments following this are interpreted as filenames. 944This can be useful when viewing a file whose name begins with a "-" or "+". 945.It Cm + 946If a command line option begins with +, 947the remainder of that option is taken to be an initial command to 948.Nm less . 949For example, +G tells 950.Nm 951to start at the end of the file rather than the beginning, 952and +/xyz tells it to start at the first occurrence of "xyz" in the file. 953As a special case, +<number> acts like +<number>g; 954that is, it starts the display at the specified line number 955(however, see the caveat under the "g" command above). 956If the option starts with ++, the initial command applies to 957every file being viewed, not just the first one. 958The + command described previously 959may also be used to set (or change) an initial command for every file. 960.El 961.Sh LINE EDITING 962When entering command line at the bottom of the screen 963(for example, a filename for the :e command, 964or the pattern for a search command), 965certain keys can be used to manipulate the command line. 966Most commands have an alternate form in [ brackets ] which can be used if 967a key does not exist on a particular keyboard. 968.\" (The bracketed forms do not work in the MS-DOS version.) 969Any of these special keys may be entered literally by preceding 970it with the "literal" character, either ^V or ^A. 971A backslash itself may also be entered literally by entering two backslashes. 972.Bl -tag -width Ds 973.It LEFTARROW [ ESC-h ] 974Move the cursor one space to the left. 975.It RIGHTARROW [ ESC-l ] 976Move the cursor one space to the right. 977.It ^LEFTARROW [ ESC-b or ESC-LEFTARROW ] 978(That is, CONTROL and LEFTARROW simultaneously.) 979Move the cursor one word to the left. 980.It ^RIGHTARROW [ ESC-w or ESC-RIGHTARROW ] 981(That is, CONTROL and RIGHTARROW simultaneously.) 982Move the cursor one word to the right. 983.It HOME [ ESC-0 ] 984Move the cursor to the beginning of the line. 985.It END [ ESC-$ ] 986Move the cursor to the end of the line. 987.It BACKSPACE 988Delete the character to the left of the cursor, 989or cancel the command if the command line is empty. 990.It DELETE or [ ESC-x ] 991Delete the character under the cursor. 992.It ^BACKSPACE [ ESC-BACKSPACE ] 993(That is, CONTROL and BACKSPACE simultaneously.) 994Delete the word to the left of the cursor. 995.It ^DELETE [ ESC-X or ESC-DELETE ] 996(That is, CONTROL and DELETE simultaneously.) 997Delete the word under the cursor. 998.It UPARROW [ ESC-k ] 999Retrieve the previous command line. 1000.It DOWNARROW [ ESC-j ] 1001Retrieve the next command line. 1002.It TAB 1003Complete the partial filename to the left of the cursor. 1004If it matches more than one filename, the first match 1005is entered into the command line. 1006Repeated TABs will cycle through the other matching filenames. 1007If the completed filename is a directory, a "/" is appended to the filename. 1008.\" (On MS-DOS systems, a "\e" is appended.) 1009The environment variable 1010.Ev LESSSEPARATOR 1011can be used to specify a different character to append to a directory name. 1012.It BACKTAB [ ESC-TAB ] 1013Like TAB, but cycles in the reverse direction through the matching filenames. 1014.It ^L 1015Complete the partial filename to the left of the cursor. 1016If it matches more than one filename, all matches are entered into 1017the command line (if they fit). 1018.\" .It ^U (Unix and OS/2) or ESC (MS-DOS) 1019.It ^U 1020Delete the entire command line, 1021or cancel the command if the command line is empty. 1022If you have changed your line-kill character to something 1023other than ^U, that character is used instead of ^U. 1024.El 1025.Sh KEY BINDINGS 1026You may define your own 1027.Nm 1028commands by using the program 1029.Xr lesskey 1 1030to create a lesskey file. 1031This file specifies a set of command keys and an action 1032associated with each key. 1033You may also use lesskey 1034to change the line-editing keys (see 1035.Sx LINE EDITING ) , 1036and to set environment variables. 1037If the environment variable 1038.Ev LESSKEY 1039is set, 1040.Nm 1041uses that as the name of the lesskey file. 1042Otherwise, 1043.Nm 1044looks for a lesskey file called "$HOME/.less". 1045.\" On MS-DOS and Windows systems, 1046.\" .I less 1047.\" looks for a lesskey file called "$HOME/_less", and if it is not found there, 1048.\" then looks for a lesskey file called "_less" in any directory specified 1049.\" in the PATH environment variable. 1050.\" On OS/2 systems, 1051.\" .I less 1052.\" looks for a lesskey file called "$HOME/less.ini", and if it is not found, 1053.\" then looks for a lesskey file called "less.ini" in any directory specified 1054.\" in the INIT environment variable, and if it not found there, 1055.\" then looks for a lesskey file called "less.ini" in any directory specified 1056.\" in the PATH environment variable. 1057See the 1058.Xr lesskey 1 1059manual page for more details. 1060.Pp 1061A system-wide lesskey file may also be set up to provide key bindings. 1062If a key is defined in both a local lesskey file and in the 1063system-wide file, key bindings in the local file take precedence over 1064those in the system-wide file. 1065If the environment variable 1066.Ev LESSKEY_SYSTEM 1067is set, 1068.Nm 1069uses that as the name of the system-wide lesskey file. 1070Otherwise, 1071.Nm 1072looks in a standard place for the system-wide lesskey file: 1073On 1074.Ox , 1075the system-wide lesskey file is 1076.Pa /etc/sysless . 1077.\" On Unix systems, the system-wide lesskey file is /usr/local/etc/sysless. 1078.\" (However, if 1079.\" .Nm less 1080.\" was built with a different sysconf directory than /usr/local/etc, 1081.\" that directory is where the sysless file is found.) 1082.\" On MS-DOS and Windows systems, the system-wide lesskey file is c:\e_sysless. 1083.\" On OS/2 systems, the system-wide lesskey file is c:\esysless.ini. 1084.Sh INPUT PREPROCESSOR 1085You may define an "input preprocessor" for 1086.Nm less . 1087Before 1088.Nm less 1089opens a file, it first gives your input preprocessor a chance to modify the 1090way the contents of the file are displayed. 1091An input preprocessor is simply an executable program (or shell script), 1092which writes the contents of the file to a different file, 1093called the replacement file. 1094The contents of the replacement file are then displayed 1095in place of the contents of the original file. 1096However, it will appear to the user as if the original file is opened; 1097that is, 1098.Nm less 1099will display the original filename as the name of the current file. 1100.Pp 1101An input preprocessor receives one command line argument, the original filename, 1102as entered by the user. 1103It should create the replacement file, and when finished 1104print the name of the replacement file to its standard output. 1105If the input preprocessor does not output a replacement filename, 1106.Nm 1107uses the original file, as normal. 1108The input preprocessor is not called when viewing standard input. 1109To set up an input preprocessor, set the 1110.Ev LESSOPEN 1111environment variable to a command line which will invoke your 1112input preprocessor. 1113This command line should include one occurrence of the string "%s", 1114which will be replaced by the filename 1115when the input preprocessor command is invoked. 1116.Pp 1117When 1118.Nm 1119closes a file opened in such a way, it will call another program, 1120called the input postprocessor, 1121which may perform any desired clean-up action (such as deleting the 1122replacement file created by 1123.Ev LESSOPEN ) . 1124This program receives two command line arguments, the original filename 1125as entered by the user, and the name of the replacement file. 1126To set up an input postprocessor, set the 1127.Ev LESSCLOSE 1128environment variable to a command line which will invoke your 1129input postprocessor. 1130It may include two occurrences of the string "%s"; 1131the first is replaced with the original name of the file and the second 1132with the name of the replacement file, which was output by 1133.Ev LESSOPEN . 1134.Pp 1135For example, these two scripts will allow you 1136to keep files in compressed format, but still let 1137.Nm 1138view them directly: 1139.Pp 1140lessopen.sh: 1141.Bd -literal -offset indent 1142#! /bin/sh 1143case "$1" in 1144*.Z) uncompress -c $1 >/tmp/less.$$ 2>/dev/null 1145 if [ -s /tmp/less.$$ ]; then 1146 echo /tmp/less.$$ 1147 else 1148 rm -f /tmp/less.$$ 1149 fi 1150 ;; 1151esac 1152.Ed 1153.Pp 1154lessclose.sh: 1155.Bd -literal -offset indent 1156#! /bin/sh 1157rm $2 1158.Ed 1159.Pp 1160To use these scripts, put them both where they can be executed and 1161set LESSOPEN="lessopen.sh\ %s", and LESSCLOSE="lessclose.sh\ %s\ %s". 1162More complex LESSOPEN and LESSCLOSE scripts may be written 1163to accept other types of compressed files, and so on. 1164.Pp 1165It is also possible to set up an input preprocessor to 1166pipe the file data directly to 1167.Nm less , 1168rather than putting the data into a replacement file. 1169This avoids the need to decompress the entire file before starting to view it. 1170An input preprocessor that works this way is called an input pipe. 1171An input pipe, instead of writing the name of a replacement file on 1172its standard output, 1173writes the entire contents of the replacement file on its standard output. 1174If the input pipe does not write any characters on its standard output, 1175then there is no replacement file and 1176.Nm 1177uses the original file, as normal. 1178To use an input pipe, make the first character in the 1179.Ev LESSOPEN 1180environment variable a vertical bar (|) to signify that the 1181input preprocessor is an input pipe. 1182.Pp 1183For example, this script will work like the previous example scripts: 1184.Pp 1185lesspipe.sh: 1186.Bd -literal -offset indent 1187#! /bin/sh 1188case "$1" in 1189*.Z) uncompress -c $1 2>/dev/null 1190 ;; 1191esac 1192.Ed 1193.Pp 1194To use this script, put it where it can be executed and set 1195LESSOPEN="|lesspipe.sh %s". 1196When an input pipe is used, a LESSCLOSE postprocessor can be used, 1197but it is usually not necessary since there is no replacement file to clean up. 1198In this case, the replacement file name passed to the LESSCLOSE 1199postprocessor is "-". 1200.Sh NATIONAL CHARACTER SETS 1201There are three types of characters in the input file: 1202.Bl -tag -width "control characters" 1203.It normal characters 1204Can be displayed directly to the screen. 1205.It control characters 1206Should not be displayed directly, but are expected to be found 1207in ordinary text files (such as backspace and tab). 1208.It binary characters 1209Should not be displayed directly and are not expected to be found 1210in text files. 1211.El 1212.Pp 1213A "character set" is simply a description of which characters are to 1214be considered normal, control, and binary. 1215The 1216.Ev LESSCHARSET 1217environment variable may be used to select a character set. 1218Possible values for 1219.Ev LESSCHARSET 1220are: 1221.Bl -tag -width "IBM-1047" 1222.It ascii 1223BS, TAB, NL, CR, and formfeed are control characters, 1224all chars with values between 32 and 126 are normal, 1225and all others are binary. 1226.It iso8859 1227Selects an ISO 8859 character set. 1228This is the same as ASCII, except characters between 160 and 255 are 1229treated as normal characters. 1230.It latin1 1231Same as iso8859. 1232.It latin9 1233Same as iso8859. 1234.It dos 1235Selects a character set appropriate for MS-DOS. 1236.It ebcdic 1237Selects an EBCDIC character set. 1238.It IBM-1047 1239Selects an EBCDIC character set used by OS/390 1240.Ux 1241Services. 1242This is the EBCDIC analogue of latin1. 1243You get similar results by setting either LESSCHARSET=IBM-1047 or 1244LC_CTYPE=en_US in your environment. 1245.It koi8-r 1246Selects a Russian character set. 1247.It next 1248Selects a character set appropriate for NeXT computers. 1249.It utf-8 1250Selects the UTF-8 encoding of the ISO 10646 character set. 1251.El 1252.Pp 1253In special cases, it may be desired to tailor 1254.Nm 1255to use a character set other than the ones definable by LESSCHARSET. 1256In this case, the environment variable 1257.Ev LESSCHARDEF 1258can be used to define a character set. 1259It should be set to a string where each character in the string represents 1260one character in the character set. 1261The character "." is used for a normal character, "c" for control, 1262and "b" for binary. 1263A decimal number may be used for repetition. 1264For example, "bccc4b." would mean character 0 is binary, 12651, 2 and 3 are control, 4, 5, 6 and 7 are binary, and 8 is normal. 1266All characters after the last are taken to be the same as the last, 1267so characters 9 through 255 would be normal. 1268(This is an example, and does not necessarily 1269represent any real character set.) 1270.Pp 1271This table shows the value of LESSCHARDEF which is equivalent 1272to each of the possible values for LESSCHARSET: 1273.Bd -literal -offset indent 1274ascii 8bcccbcc18b95.b 1275dos 8bcccbcc12bc5b95.b. 1276ebcdic 5bc6bcc7bcc41b.9b7.9b5.b..8b6.10b6.b9.7b 1277 9.8b8.17b3.3b9.7b9.8b8.6b10.b.b.b. 1278IBM-1047 4cbcbc3b9cbccbccbb4c6bcc5b3cbbc4bc4bccbc 1279 191.b 1280iso8859 8bcccbcc18b95.33b. 1281koi8-r 8bcccbcc18b95.b128. 1282latin1 8bcccbcc18b95.33b. 1283next 8bcccbcc18b95.bb125.bb 1284.Ed 1285.Pp 1286If neither LESSCHARSET nor LESSCHARDEF is set, 1287but the string "UTF-8" is found in the 1288.Ev LC_ALL , LC_CTYPE 1289or 1290.Ev LANG 1291environment variables, then the default character set is utf-8. 1292.Pp 1293If that string is not found, but your system supports the 1294setlocale interface, 1295.Nm 1296will use setlocale to determine the character set. 1297setlocale is controlled by setting the 1298.Ev LANG 1299or 1300.Ev LC_CTYPE 1301environment variables. 1302.Pp 1303Finally, if the 1304setlocale interface is also not available, the default character set is latin1. 1305.Pp 1306Control and binary characters are displayed in standout (reverse video). 1307Each such character is displayed in caret notation if possible 1308(e.g. ^A for control-A). 1309Caret notation is used only if inverting the 0100 bit results in a 1310normal printable character. 1311Otherwise, the character is displayed as a hex number in angle brackets. 1312This format can be changed by setting the 1313.Ev LESSBINFMT 1314environment variable. 1315LESSBINFMT may begin with a "*" and one character to select 1316the display attribute: 1317"*k" is blinking, "*d" is bold, "*u" is underlined, "*s" is standout, 1318and "*n" is normal. 1319If LESSBINFMT does not begin with a "*", normal attribute is assumed. 1320The remainder of LESSBINFMT is a string which may include one 1321printf-style escape sequence (a % followed by x, X, o, d, etc.). 1322For example, if LESSBINFMT is "*u[%x]", binary characters 1323are displayed in underlined hexadecimal surrounded by brackets. 1324The default if no LESSBINFMT is specified is "*s<%X>". 1325.Sh PROMPTS 1326The -P option allows you to tailor the prompt to your preference. 1327The string given to the -P option replaces the specified prompt string. 1328Certain characters in the string are interpreted specially. 1329The prompt mechanism is rather complicated to provide flexibility, 1330but the ordinary user need not understand the details of constructing 1331personalized prompt strings. 1332.Pp 1333A percent sign followed by a single character is expanded 1334according to what the following character is: 1335.Bl -tag -width Ds 1336.It %b Ns Ar X 1337Replaced by the byte offset into the current input file. 1338The b is followed by a single character (shown as 1339.Ar X 1340above) which specifies the line whose byte offset is to be used. 1341If the character is a "t", the byte offset of the top line in the 1342display is used, 1343an "m" means use the middle line, 1344a "b" means use the bottom line, 1345a "B" means use the line just after the bottom line, 1346and a "j" means use the "target" line, as specified by the -j option. 1347.It \&%B 1348Replaced by the size of the current input file. 1349.It %c 1350Replaced by the column number of the text appearing in the first 1351column of the screen. 1352.It %d Ns Ar X 1353Replaced by the page number of a line in the input file. 1354The line to be used is determined by the 1355.Ar X , 1356as with the %b option. 1357.It \&%D 1358Replaced by the number of pages in the input file, 1359or equivalently, the page number of the last line in the input file. 1360.It %E 1361Replaced by the name of the editor (from the 1362.Ev VISUAL 1363environment variable, or the 1364.Ev EDITOR 1365environment variable if 1366.Ev VISUAL 1367is not defined). 1368See the discussion of the LESSEDIT feature below. 1369.It %f 1370Replaced by the name of the current input file. 1371.It %i 1372Replaced by the index of the current file in the list of 1373input files. 1374.It %l Ns Ar X 1375Replaced by the line number of a line in the input file. 1376The line to be used is determined by the 1377.Ar X , 1378as with the %b option. 1379.It %L 1380Replaced by the line number of the last line in the input file. 1381.It %m 1382Replaced by the total number of input files. 1383.It %p Ns Ar X 1384Replaced by the percent into the current input file, based on byte offsets. 1385The line used is determined by the 1386.Ar X , 1387as with the %b option. 1388.It \&%P Ns Ar X 1389Replaced by the percent into the current input file, based on line numbers. 1390The line used is determined by the 1391.Ar X , 1392as with the %b option. 1393.It %s 1394Same as %B. 1395.It %t 1396Causes any trailing spaces to be removed. 1397Usually used at the end of the string, but may appear anywhere. 1398.It %x 1399Replaced by the name of the next input file in the list. 1400.El 1401.Pp 1402If any item is unknown (for example, the file size if input is a pipe), 1403a question mark is printed instead. 1404.Pp 1405The format of the prompt string can be changed depending on certain conditions. 1406A question mark followed by a single character acts like an "IF": 1407depending on the following character, a condition is evaluated. 1408If the condition is true, any characters following the question mark 1409and condition character, up to a period, are included in the prompt. 1410If the condition is false, such characters are not included. 1411A colon appearing between the question mark and the 1412period can be used to establish an "ELSE": any characters between 1413the colon and the period are included in the string, if and only if 1414the IF condition is false. 1415Condition characters (which follow a question mark) may be: 1416.Bl -tag -width Ds 1417.It ?a 1418True if any characters have been included in the prompt so far. 1419.It ?b Ns Ar X 1420True if the byte offset of the specified line is known. 1421.It ?B 1422True if the size of the current input file is known. 1423.It ?c 1424True if the text is horizontally shifted (%c is not zero). 1425.It ?d Ns Ar X 1426True if the page number of the specified line is known. 1427.It ?e 1428True if at end-of-file. 1429.It ?f 1430True if there is an input filename 1431(that is, if input is not a pipe). 1432.It ?l Ns Ar X 1433True if the line number of the specified line is known. 1434.It ?L 1435True if the line number of the last line in the file is known. 1436.It ?m 1437True if there is more than one input file. 1438.It ?n 1439True if this is the first prompt in a new input file. 1440.It ?p Ns Ar X 1441True if the percent into the current input file, based on byte offsets, 1442of the specified line is known. 1443.It ?P Ns Ar X 1444True if the percent into the current input file, based on line numbers, 1445of the specified line is known. 1446.It ?s 1447Same as "?B". 1448.It ?x 1449True if there is a next input file 1450(that is, if the current input file is not the last one). 1451.El 1452.Pp 1453Any characters other than the special ones 1454(question mark, colon, period, percent, and backslash) 1455become literally part of the prompt. 1456Any of the special characters may be included in the prompt literally 1457by preceding it with a backslash. 1458.Pp 1459Some examples: 1460.Pp 1461.Dl ?f%f:Standard input. 1462.Pp 1463This prompt prints the filename, if known; 1464otherwise the string "Standard input". 1465.Pp 1466.Dl ?f%f .?ltLine %lt:?pt%pt\e%:?btByte %bt:-... 1467.Pp 1468This prompt would print the filename, if known. 1469The filename is followed by the line number, if known, 1470otherwise the percent if known, otherwise the byte offset if known. 1471Otherwise, a dash is printed. 1472Notice how each question mark has a matching period, 1473and how the % after the %pt 1474is included literally by escaping it with a backslash. 1475.Pp 1476.Dl ?n?f%f\ .?m(file\ %i\ of\ %m)\ ..?e(END)\ ?x-\ Next\e:\ %x..%t 1477.Pp 1478This prints the filename if this is the first prompt in a file, 1479followed by the "file N of N" message if there is more 1480than one input file. 1481Then, if we are at end-of-file, the string "(END)" is printed 1482followed by the name of the next file, if there is one. 1483Finally, any trailing spaces are truncated. 1484This is the default prompt. 1485For reference, here are the defaults for 1486the other two prompts (-m and -M respectively). 1487Each is broken into two lines here for readability only. 1488.Bd -literal -offset indent 1489?f%f\ .?m(file\ %i\ of\ %m)\ .?e(END)\ ?x-\ Next\e:\ %x.: 1490 ?pB%pB\e%:byte\ %bB?s/%s...%t 1491 1492?f%f\ .?n?m(file\ %i\ of\ %m)\ ..?ltlines\ %lt-%lb?L/%L.\ : 1493 byte\ %bB?s/%s.\ .?e(END)\ ?x-\ Next\e:\ %x.:?pB%pB\e%..%t 1494.Ed 1495.Pp 1496And here is the default message produced by the = command: 1497.Bd -literal -offset indent 1498?f%f\ .?m(file\ %i\ of\ %m)\ .?ltlines\ %lt-%lb?L/%L.\ . 1499 byte\ %bB?s/%s.\ ?e(END)\ :?pB%pB\e%..%t 1500.Ed 1501.Pp 1502The prompt expansion features are also used for another purpose: 1503if an environment variable 1504.Ev LESSEDIT 1505is defined, it is used as the command to be executed when the v command 1506is invoked. 1507The LESSEDIT string is expanded in the same way as the prompt strings. 1508The default value for LESSEDIT is: 1509.Pp 1510.Dl %E\ ?lm+%lm.\ %f 1511.Pp 1512Note that this expands to the editor name, followed by a + and the 1513line number, followed by the file name. 1514If your editor does not accept the "+linenumber" syntax, or has other 1515differences in invocation syntax, the 1516.Ev LESSEDIT 1517variable can be changed to modify this default. 1518.Sh SECURITY 1519When the environment variable 1520.Ev LESSSECURE 1521is set to 1, 1522.Nm 1523runs in a "secure" mode. 1524This means these features are disabled: 1525.Bl -tag -width Ds 1526.It \&! 1527The shell command. 1528.It | 1529The pipe command. 1530.It :e 1531The examine command. 1532.It v 1533The editing command. 1534.It s -o 1535Log files. 1536.It -k 1537Use of lesskey files. 1538.It -t 1539Use of tags files. 1540.It " " 1541Metacharacters in filenames, such as "*". 1542.It " " 1543Filename completion (TAB, ^L). 1544.El 1545.Pp 1546Less can also be compiled to be permanently in "secure" mode. 1547.Sh ENVIRONMENT 1548Environment variables may be specified either in the system environment 1549as usual, or in a 1550.Xr lesskey 1 1551file. 1552If environment variables are defined in more than one place, 1553variables defined in a local lesskey file take precedence over 1554variables defined in the system environment, which take precedence 1555over variables defined in the system-wide lesskey file. 1556.Bl -tag -width Ds 1557.It Ev COLUMNS 1558Sets the number of columns on the screen. 1559Takes precedence over the number of columns specified by the TERM variable. 1560(But if you have a windowing system which supports TIOCGWINSZ or WIOCGETD, 1561the window system's idea of the screen size takes precedence over the 1562LINES and COLUMNS environment variables.) 1563.It Ev EDITOR 1564The name of the editor (used for the v command). 1565.It Ev HOME 1566Name of the user's home directory 1567(used to find a lesskey file). 1568.\" .It Ev "HOMEDRIVE, HOMEPATH" 1569.\" Concatenation of the HOMEDRIVE and HOMEPATH environment variables is 1570.\" the name of the user's home directory if the HOME variable is not set 1571.\" (only in the Windows version). 1572.\" .It Ev INIT 1573.\" Name of the user's init directory 1574.\" (used to find a lesskey file on OS/2 systems). 1575.It Ev LANG 1576Language for determining the character set. 1577.It Ev LC_CTYPE 1578Language for determining the character set. 1579.It Ev LESS 1580Options which are passed to 1581.Nm 1582automatically. 1583.It Ev LESSANSIENDCHARS 1584Characters which are assumed to end an ANSI color escape sequence 1585(default "m"). 1586.It Ev LESSBINFMT 1587Format for displaying non-printable, non-control characters. 1588.It Ev LESSCHARDEF 1589Defines a character set. 1590.It Ev LESSCHARSET 1591Selects a predefined character set. 1592.It Ev LESSCLOSE 1593Command line to invoke the (optional) input-postprocessor. 1594.\" .It Ev LESSECHO 1595.\" Name of the lessecho program (default "lessecho"). 1596.\" The lessecho program is needed to expand metacharacters, such as * and ?, 1597.\" in filenames on Unix systems. 1598.It Ev LESSEDIT 1599Editor prototype string (used for the v command). 1600See discussion under 1601.Sx PROMPTS . 1602.It Ev LESSGLOBALTAGS 1603Name of the command used by the -t option to find global tags. 1604Normally should be set to "global" if your system has the global command. 1605If not set, global tags are not used. 1606.It Ev LESSKEY 1607Name of the default lesskey(1) file. 1608.It Ev LESSKEY_SYSTEM 1609Name of the default system-wide lesskey(1) file. 1610.It Ev LESSMETACHARS 1611List of characters which are considered "metacharacters" by the shell. 1612.It Ev LESSMETAESCAPE 1613Prefix which 1614.Nm 1615will add before each metacharacter in a command sent to the shell. 1616If LESSMETAESCAPE is an empty string, commands containing 1617metacharacters will not be passed to the shell. 1618.It Ev LESSOPEN 1619Command line to invoke the (optional) input-preprocessor. 1620.It Ev LESSSECURE 1621Runs less in "secure" mode. 1622See discussion under 1623.Sx SECURITY . 1624.It Ev LESSSEPARATOR 1625String to be appended to a directory name in filename completion. 1626.It Ev LINES 1627Sets the number of lines on the screen. 1628Takes precedence over the number of lines specified by the TERM variable. 1629(But if you have a windowing system which supports TIOCGWINSZ or WIOCGETD, 1630the window system's idea of the screen size takes precedence over the 1631LINES and COLUMNS environment variables.) 1632.\" .It Ev PATH 1633.\" User's search path (used to find a lesskey file 1634.\" on MS-DOS and OS/2 systems). 1635.It Ev SHELL 1636The shell used to execute the ! command, as well as to expand filenames. 1637.It Ev TERM 1638The type of terminal on which 1639.Nm 1640is being run. 1641.It Ev VISUAL 1642The name of the editor (used for the v command). 1643.El 1644.Sh SEE ALSO 1645.Xr lesskey 1 1646.Sh STANDARDS 1647The 1648.Nm more 1649utility is compliant with the 1650.St -p1003.1-2008 1651specification, 1652though its presence is optional. 1653.Pp 1654The flags 1655.Op Fl aBbCdEFfGghIJjkLMmNOoPQqRrSTUVWwXxyz~# 1656are extensions to that specification. 1657.Sh AUTHORS 1658.An Mark Nudelman Aq markn@greenwoodsoftware.com 1659.Pp 1660Send bug reports or comments to the above address or to 1661.Aq bug\-less@gnu.org . 1662.Pp 1663For more information, see the less homepage at 1664.Pa http://www.greenwoodsoftware.com/less . 1665.Sh CAVEATS 1666The = command and prompts (unless changed by -P) 1667report the line numbers of the lines at the top and bottom of the screen, 1668but the byte and percent of the line after the one at the bottom of the screen. 1669.Pp 1670If the :e command is used to name more than one file, 1671and one of the named files has been viewed previously, 1672the new files may be entered into the list in an unexpected order. 1673.Pp 1674On certain older terminals (the so-called "magic cookie" terminals), 1675search highlighting will cause an erroneous display. 1676On such terminals, search highlighting is disabled by default 1677to avoid possible problems. 1678.Pp 1679In certain cases, when search highlighting is enabled and 1680a search pattern begins with a ^, 1681more text than the matching string may be highlighted. 1682(This problem does not occur when 1683.Nm 1684is compiled to use the POSIX regular expression package.) 1685.Pp 1686When viewing text containing ANSI color escape sequences using the -R option, 1687searching will not find text containing an embedded escape sequence. 1688Also, search highlighting may change the color of some of the text 1689which follows the highlighted text. 1690.Pp 1691On some systems, setlocale claims that ASCII characters 0 through 31 are 1692control characters rather than binary characters. 1693This causes 1694.Nm 1695to treat some binary files as ordinary, non-binary files. 1696To workaround this problem, set the environment variable 1697.Ev LESSCHARSET 1698to "ascii" (or whatever character set is appropriate). 1699.Pp 1700See 1701.Pa http://www.greenwoodsoftware.com/less 1702for the latest list of known bugs in this version of 1703.Nm less . 1704