1.\" $OpenBSD: less.1,v 1.27 2012/03/30 17:12:33 jmc Exp $ 2.\" 3.\" Copyright (C) 1984-2011 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: March 30 2012 $ 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 AaBCcdEeFfGgIiJKLMmNnQqRrSsUuVWwX~ 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 screenful, even if it reaches 116end-of-file in the process. 117.It Ic ENTER | 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, and may contain a decimal point. 169.It Ic P 170Go to the line containing byte offset N in the file. 171.It Ic { 172If a left curly bracket appears in the top line displayed 173on the screen, the { command will go to the matching right curly bracket. 174The matching right curly bracket is positioned on the bottom 175line of the screen. 176If there is more than one left curly bracket on the top line, a number N 177may be used to specify the N-th bracket on the line. 178.It Ic } 179If a right curly bracket appears in the bottom line displayed on the screen, 180the } command will go to the matching left curly bracket. 181The matching left curly bracket is positioned on the top 182line of the screen. 183If there is more than one right curly bracket on the top line, 184a number N may be used to specify the N-th bracket on the line. 185.It Ic \&( 186Like {, but applies to parentheses rather than curly brackets. 187.It Ic \&) 188Like }, but applies to parentheses rather than curly brackets. 189.It Ic \&[ 190Like {, but applies to square brackets rather than curly brackets. 191.It Ic \&] 192Like }, but applies to square brackets rather than curly brackets. 193.It Ic ESC-^F 194Followed by two characters, acts like {, 195but uses the two characters as open and close brackets, respectively. 196For example, "ESC ^F < >" could be used to 197go forward to the > which matches the < in the top displayed line. 198.It Ic ESC-^B 199Followed by two characters, acts like }, 200but uses the two characters as open and close brackets, respectively. 201For example, "ESC ^B < >" could be used to 202go backward to the < which matches the > in the bottom displayed line. 203.It Ic m 204Followed by any lowercase letter, marks the current position with that letter. 205.It Ic ' 206(Single quote.) 207Followed by any lowercase letter, returns to the position which 208was previously marked with that letter. 209Followed by another single quote, returns to the position at 210which the last "large" movement command was executed. 211Followed by a ^ or $, jumps to the beginning or end of the file respectively. 212Marks are preserved when a new file is examined, 213so the ' command can be used to switch between input files. 214.It Ic ^X^X 215Same as single quote. 216.It Ic /pattern 217Search forward in the file for the N-th line containing the pattern. 218N defaults to 1. 219The pattern is a regular expression, as recognized by 220the regular expression library supplied by your system. 221The search starts at the first line displayed 222(but see the -a and -j options, which change this). 223.Pp 224Certain characters are special if entered at the beginning of the pattern; 225they modify the type of search rather than become part of the pattern: 226.Bl -tag -width Ds 227.It Ic ^N | \&! 228Search for lines which do NOT match the pattern. 229.It Ic ^E | * 230Search multiple files. 231That is, if the search reaches the END of the current file 232without finding a match, 233the search continues in the next file in the command line list. 234.It Ic ^F | @ 235Begin the search at the first line of the FIRST file 236in the command line list, 237regardless of what is currently displayed on the screen 238or the settings of the -a or -j options. 239.It Ic ^K 240Highlight any text which matches the pattern on the current screen, 241but don't move to the first match (KEEP current position). 242.It Ic ^R 243Don't interpret regular expression metacharacters; 244that is, do a simple textual comparison. 245.El 246.It Ic ?pattern 247Search backward in the file for the N-th line containing the pattern. 248The search starts at the line immediately before the top line displayed. 249.Pp 250Certain characters are special, as in the / command: 251.Bl -tag -width Ds 252.It Ic ^N | \&! 253Search for lines which do NOT match the pattern. 254.It Ic ^E | * 255Search multiple files. 256That is, if the search reaches the beginning of the current file 257without finding a match, 258the search continues in the previous file in the command line list. 259.It Ic ^F | @ 260Begin the search at the last line of the last file 261in the command line list, 262regardless of what is currently displayed on the screen 263or the settings of the -a or -j options. 264.It Ic ^K 265As in forward searches. 266.It Ic ^R 267As in forward searches. 268.El 269.It Ic ESC-/pattern 270Same as "/*". 271.It Ic ESC-?pattern 272Same as "?*". 273.It Ic n 274Repeat previous search, for N-th line containing the last pattern. 275If the previous search was modified by ^N, the search is made for the 276N-th line NOT containing the pattern. 277If the previous search was modified by ^E, the search continues 278in the next (or previous) file if not satisfied in the current file. 279If the previous search was modified by ^R, the search is done 280without using regular expressions. 281There is no effect if the previous search was modified by ^F or ^K. 282.It Ic N 283Repeat previous search, but in the reverse direction. 284.It Ic ESC-n 285Repeat previous search, but crossing file boundaries. 286The effect is as if the previous search were modified by *. 287.It Ic ESC-N 288Repeat previous search, but in the reverse direction 289and crossing file boundaries. 290.It Ic ESC-u 291Undo search highlighting. 292Turn off highlighting of strings matching the current search pattern. 293If highlighting is already off because of a previous ESC-u command, 294turn highlighting back on. 295Any search command will also turn highlighting back on. 296(Highlighting can also be disabled by toggling the -G option; 297in that case search commands do not turn highlighting back on.) 298.It Ic &pattern 299Display only lines which match the pattern; 300lines which do not match the pattern are not displayed. 301If pattern is empty (if you type & immediately followed by ENTER), 302any filtering is turned off, and all lines are displayed. 303While filtering is in effect, an ampersand is displayed at the 304beginning of the prompt, 305as a reminder that some lines in the file may be hidden. 306.Pp 307Certain characters are special as in the / command: 308.Bl -tag -width Ds 309.It Ic ^N | ! 310Display only lines which do NOT match the pattern. 311.It Ic ^R 312Don't interpret regular expression metacharacters; 313that is, do a simple textual comparison. 314.El 315.It Ic :e Op Ar filename 316Examine a new file. 317If the filename is missing, the "current" file (see the :n and :p commands 318below) from the list of files in the command line is re-examined. 319A percent sign (%) in the filename is replaced by the name of the 320current file. 321A pound sign (#) is replaced by the name of the previously examined file. 322However, two consecutive percent signs are simply 323replaced with a single percent sign. 324This allows you to enter a filename that contains a percent sign 325in the name. 326Similarly, two consecutive pound signs are replaced with a single pound sign. 327The filename is inserted into the command line list of files 328so that it can be seen by subsequent :n and :p commands. 329If the filename consists of several files, they are all inserted into 330the list of files and the first one is examined. 331If the filename contains one or more spaces, 332the entire filename should be enclosed in double quotes 333(also see the -" option). 334.It Ic ^X^V | E 335Same as :e. 336Warning: some systems use ^V as a special literalization character. 337On such systems, you may not be able to use ^V. 338.It Ic :n 339Examine the next file (from the list of files given in the command line). 340If a number N is specified, the N-th next file is examined. 341.It Ic :p 342Examine the previous file in the command line list. 343If a number N is specified, the N-th previous file is examined. 344.It Ic :t 345Go to the specified tag. 346.It Ic :x 347Examine the first file in the command line list. 348If a number N is specified, the N-th file in the list is examined. 349.It Ic :d 350Remove the current file from the list of files. 351.It Ic t 352Go to the next tag, if there were more than one matches for the current tag. 353See the \-t option for more details about tags. 354.It Ic T 355Go to the previous tag, if there were more than one matches for the current tag. 356.It Ic = | ^G | :f 357Prints some information about the file being viewed, including its name 358and the line number and byte offset of the bottom line being displayed. 359If possible, it also prints the length of the file, 360the number of lines in the file 361and the percent of the file above the last displayed line. 362.It Ic \- 363Followed by one of the command line option letters (see 364.Sx OPTIONS 365below), 366this will change the setting of that option 367and print a message describing the new setting. 368If a ^P (CONTROL-P) is entered immediately after the dash, 369the setting of the option is changed but no message is printed. 370If the option letter has a numeric value (such as -b or -h), 371or a string value (such as -P or -t), 372a new value may be entered after the option letter. 373If no new value is entered, a message describing 374the current setting is printed and nothing is changed. 375.It Ic \-\- 376Like the \- command, but takes a long option name (see 377.Sx OPTIONS 378below) 379rather than a single option letter. 380You must press ENTER or RETURN after typing the option name. 381A ^P immediately after the second dash suppresses printing of a 382message describing the new setting, as in the \- command. 383.It Ic \-+ 384Followed by one of the command line option letters this will reset the 385option to its default setting and print a message describing the new setting. 386(The "\-+X" command does the same thing as "\-+X" on the command line.) 387This does not work for string-valued options. 388.It Ic \-\-+ 389Like the \-+ command, but takes a long option name 390rather than a single option letter. 391.It Ic \-! 392Followed by one of the command line option letters, this will reset the 393option to the "opposite" of its default setting and print a message 394describing the new setting. 395This does not work for numeric or string-valued options. 396.It Ic \-\-! 397Like the \-! command, but takes a long option name 398rather than a single option letter. 399.It Ic _ 400(Underscore.) 401Followed by one of the command line option letters, 402this will print a message describing the current setting of that option. 403The setting of the option is not changed. 404.It Ic __ 405(Double underscore.) 406Like the _ (underscore) command, but takes a long option name 407rather than a single option letter. 408You must press ENTER or RETURN after typing the option name. 409.It Ic +cmd 410Causes the specified cmd to be executed each time a new file is examined. 411For example, +G causes 412.Nm 413to initially display each file starting at the end rather than the beginning. 414.It Ic V 415Prints the version number of 416.Nm 417being run. 418.It Ic q | Q | :q | :Q | ZZ 419Exits 420.Nm less . 421.El 422.Pp 423The following 424four 425commands may or may not be valid, depending on your particular installation. 426.Bl -tag -width XXXX 427.It Ic v 428Invokes an editor to edit the current file being viewed. 429The editor is taken from the environment variable 430.Ev VISUAL , 431if defined, 432or 433.Ev EDITOR 434if 435.Ev VISUAL 436is not defined, 437or defaults to "vi" if neither 438.Ev VISUAL 439nor 440.Ev EDITOR 441is defined. 442See also the discussion of LESSEDIT under the section on 443.Sx PROMPTS 444below. 445.It Ic \&! Ar shell-command 446Invokes a shell to run the shell-command given. 447A percent sign (%) in the command is replaced by the name of the current file. 448A pound sign (#) is replaced by the name of the previously examined file. 449"!!" repeats the last shell command. 450"!" with no shell command simply invokes a shell. 451The shell is taken from the environment variable 452.Ev SHELL , 453or defaults to "sh". 454.\" On MS-DOS and OS/2 systems, the shell is the normal command processor. 455.It Ic | <m> Ar shell-command 456<m> represents any mark letter. 457Pipes a section of the input file to the given shell command. 458The section of the file to be piped is between the first line on 459the current screen and the position marked by the letter. 460<m> may also be ^ or $ to indicate beginning or end of file respectively. 461If <m> is . or newline, the current screen is piped. 462.It Ic s Ar filename 463Save the input to a file. 464This only works if the input is a pipe, not an ordinary file. 465.El 466.Sh OPTIONS 467Command line options are described below. 468Most options may be changed while 469.Nm 470is running, via the "\-" command. 471.Pp 472Most options may be given in one of two forms: 473either a dash followed by a single letter, or two dashes followed by a 474long option name. 475A long option name may be abbreviated as long as the abbreviation is 476unambiguous. 477For example, --quit-at-eof may be abbreviated --quit, but not 478--qui, since both --quit-at-eof and --quiet begin with --qui. 479Some long option names are in uppercase, such as --QUIT-AT-EOF, as 480distinct from --quit-at-eof. 481Such option names need only have their first letter capitalized; 482the remainder of the name may be in either case. 483For example, --Quit-at-eof is equivalent to --QUIT-AT-EOF. 484.Pp 485Options are also taken from the environment variable 486.Ev LESS 487if the command is 488.Nm less , 489or from the environment variable 490.Ev MORE 491if the command is 492.Nm more . 493For example, to avoid typing "less -options ..." each time 494.Nm 495is invoked, you might tell 496.Xr csh 1 : 497.Pp 498.Dl setenv LESS "-options" 499.Pp 500or if you use 501.Xr sh 1 : 502.Pp 503.Dl LESS="-options"; export LESS 504.Pp 505.\" On MS-DOS, you don't need the quotes, but you should replace any 506.\" percent signs in the options string by double percent signs. 507.\" .Pp 508The environment variable is parsed before the command line, 509so command line options override the 510.Ev LESS 511environment variable. 512If an option appears in the 513.Ev LESS 514variable, it can be reset to its default value on the command line by 515beginning the command line option with "\-+". 516.Pp 517For options like -P which take a following string, 518a dollar sign ($) must be used to signal the end of the string. 519For example, to separate a prompt value from any other options 520with dollar sign between them: 521.Pp 522.Dl LESS="-Ps--More--$-C -e" 523.Bl -tag -width XXXX 524.It Fl \&? | -help 525This option displays a summary of the commands accepted by 526.Nm 527(the same as the h command). 528(Depending on how your shell interprets the question mark, 529it may be necessary to quote the question mark, thus: "-\e?".) 530.It Fl A | -SEARCH-SKIP-SCREEN 531Causes all forward searches (not just non-repeated searches) 532to start just after the target line, and all backward searches 533to start just before the target line. 534Thus, forward searches will skip part of the displayed screen 535(from the first line up to and including the target line). 536Similarly backwards searches will skip the displayed screen 537from the last line up to and including the target line. 538This was the default behavior in less versions prior to 441. 539.It Fl a | -search-skip-screen 540By default, forward searches start at the top of the displayed screen 541and backwards searches start at the bottom of the displayed screen 542(except for repeated searches invoked by the n or N commands, 543which start after or before the "target" line respectively; 544see the -j option for more about the target line). 545The -a option causes forward searches to instead start at 546the bottom of the screen 547and backward searches to start at the top of the screen, 548thus skipping all lines displayed on the screen. 549.It Fl B | -auto-buffers 550By default, when data is read from a pipe, 551buffers are allocated automatically as needed. 552If a large amount of data is read from the pipe, this can cause 553a large amount of memory to be allocated. 554The -B option disables this automatic allocation of buffers for pipes, 555so that only 64K (or the amount of space specified by the -b option) 556is used for the pipe. 557Warning: use of -B can result in erroneous display, since only the 558most recently viewed part of the piped data is kept in memory; 559any earlier data is lost. 560.It Xo 561.Fl b Ns Ar n | 562.Fl -buffers Ns = Ns Ar n 563.Xc 564Specifies the amount of buffer space 565.Nm 566will use for each file, in units of kilobytes (1024 bytes). 567By default 64K of buffer space is used for each file 568(unless the file is a pipe; see the -B option). 569The -b option specifies instead that n kilobytes of 570buffer space should be used for each file. 571If n is -1, buffer space is unlimited; that is, 572the entire file can be read into memory. 573.It Fl C | -CLEAR-SCREEN 574Same as -c, for compatibility with older versions of 575.Nm less . 576.It Fl c | -clear-screen 577Causes full screen repaints to be painted from the bottom of the screen. 578By default, full screen repaints are done from the top line down 579to avoid the position of the display being moved 580when using interactive commands. 581.It Fl d | -dumb No (less only) 582The -d option suppresses the error message 583normally displayed if the terminal is dumb; 584that is, lacks some important capability, 585such as the ability to clear the screen or scroll backward. 586The -d option does not otherwise change the behavior of 587.Nm 588on a dumb terminal. 589This option is on by default when invoked as 590.Nm more . 591.It Fl d No (more only) 592The -d option causes the default prompt to include the 593basic directions ``[Press space to continue, 'q' to quit.]''. 594The -d option also causes the message ``[Press 'h' for instructions.]'' to be 595displayed when an invalid command is entered (normally, the bell is rung). 596This option is useful in environments where users may not be experienced 597with pagers. 598.\" .It Fl Dxcolor or --color=xcolor" 599.\" [MS-DOS only] 600.\" Sets the color of the text displayed. 601.\" x is a single character which selects the type of text whose color is 602.\" being set: n=normal, s=standout, d=bold, u=underlined, k=blink. 603.\" color is a pair of numbers separated by a period. 604.\" The first number selects the foreground color and the second selects 605.\" the background color of the text. 606.\" A single number N is the same as N.M, 607.\" where M is the normal background color. 608.It Fl E | -QUIT-AT-EOF 609Causes 610.Nm 611to automatically exit the first time it reaches end-of-file. 612.It Fl e | -quit-at-eof 613Causes 614.Nm 615to automatically exit the second time it reaches end-of-file. 616By default, the only way to exit 617.Nm 618is via the "q" command. 619.It Fl F | -quit-if-one-screen 620Causes 621.Nm 622to automatically exit if the entire file can be displayed on the first screen. 623.It Fl f | -force 624Forces non-regular files to be opened. 625(A non-regular file is a directory or a device special file.) 626Also suppresses the warning message when a binary file is opened. 627By default, 628.Nm 629will refuse to open non-regular files. 630.It Fl G | -HILITE-SEARCH 631The -G option suppresses all highlighting of strings found by search commands. 632.It Fl g | -hilite-search 633Normally, 634.Nm 635will highlight ALL strings which match the last search command. 636The -g option changes this behavior to highlight only the particular string 637which was found by the last search command. 638This can cause 639.Nm 640to run somewhat faster than the default. 641.It Xo 642.Fl h Ns Ar n | 643.Fl -max-back-scroll Ns = Ns Ar n 644.Xc 645Specifies a maximum number of lines to scroll backward. 646If it is necessary to scroll backward more than n lines, 647the screen is repainted in a forward direction instead. 648(If the terminal does not have the ability to scroll backward, -h0 is implied.) 649.It Fl I | -IGNORE-CASE 650Like -i, but searches ignore case even if the pattern contains uppercase 651letters. 652.It Fl i | -ignore-case 653Causes searches to ignore case; that is, 654uppercase and lowercase are considered identical. 655This option is ignored if any uppercase letters appear in the search pattern; 656in other words, 657if a pattern contains uppercase letters, then that search does not ignore case. 658.It Fl J | -status-column 659Displays a status column at the left edge of the screen. 660The status column shows the lines that matched the current search. 661The status column is also used if the -w or -W option is in effect. 662.It Xo 663.Fl j Ns Ar n | 664.Fl -jump-target Ns = Ns Ar n 665.Xc 666Specifies a line on the screen where the "target" line is to be positioned. 667The target line is the line specified by any command to 668search for a pattern, jump to a line number, 669jump to a file percentage or jump to a tag. 670The screen line may be specified by a number: the top line on the screen 671is 1, the next is 2, and so on. 672The number may be negative to specify a line relative to the bottom 673of the screen: the bottom line on the screen is -1, the second 674to the bottom is -2, and so on. 675Alternately, the screen line may be specified as a fraction of the height 676of the screen, starting with a decimal point: .5 is in the middle of the 677screen, .3 is three tenths down from the first line, and so on. 678If the line is specified as a fraction, the actual line number 679is recalculated if the terminal window is resized, so that the 680target line remains at the specified fraction of the screen height. 681If any form of the -j option is used, 682forward searches begin at the line immediately after the target line, 683and backward searches begin at the target line, 684unless changed by -a or -A. 685For example, if "-j4" is used, the target line is the 686fourth line on the screen, so forward searches begin at the fifth line 687on the screen. 688.It Fl K | -quit-on-intr 689Causes 690.Nm 691to exit immediately (with status 2) 692when an interrupt character (usually ^C) is typed. 693Normally, an interrupt character causes 694.Nm 695to stop whatever it is doing and return to its command prompt. 696Note that use of this option makes it impossible to return to the 697command prompt from the "F" command. 698.It Xo 699.Fl k Ns Ar filename | 700.Fl -lesskey-file Ns = Ns Ar filename 701.Xc 702Causes 703.Nm 704to open and interpret the named file as a 705.Xr lesskey 1 706file. 707Multiple -k options may be specified. 708If the 709.Ev LESSKEY 710or 711.Ev LESSKEY_SYSTEM 712environment variable is set, or if a lesskey file is found in a standard place 713(see 714.Sx KEY BINDINGS ) , 715it is also used as a lesskey file. 716.It Fl L | -no-lessopen 717Ignore the 718.Ev LESSOPEN 719environment variable (see the 720.Sx INPUT PREPROCESSOR 721section below). 722This option can be set from within 723.Nm less , 724but it will apply only to files opened subsequently, not to the 725file which is currently open. 726When invoked as 727.Nm more , 728the 729.Ev LESSOPEN 730environment variable is ignored by default. 731.It Fl M | -LONG-PROMPT 732Causes 733.Nm 734to prompt even more verbosely than 735.Nm more . 736.It Fl m | -long-prompt 737Causes 738.Nm 739to prompt verbosely (like more), with the percent into the file. 740By default, 741.Nm 742prompts with a colon. 743.It Fl N | -LINE-NUMBERS 744Causes a line number to be displayed at the beginning of each line in the 745display. 746.It Fl n | -line-numbers 747Suppresses line numbers. 748The default (to use line numbers) may cause 749.Nm 750to run more slowly in some cases, especially with a very large input file. 751Suppressing line numbers with the -n option will avoid this problem. 752Using line numbers means: the line number will be displayed in the verbose 753prompt and in the = command, and the v command will pass the current line 754number to the editor (see also the discussion of LESSEDIT in 755.Sx PROMPTS 756below). 757.It Xo 758.Fl O Ns Ar filename | 759.Fl -LOG-FILE Ns = Ns Ar filename 760.Xc 761The -O option is like -o, but it will overwrite an existing 762file without asking for confirmation. 763.Pp 764If no log file has been specified, 765the -o and -O options can be used from within 766.Nm 767to specify a log file. 768Without a file name, they will simply report the name of the log file. 769The "s" command is equivalent to specifying -o from within 770.Nm less . 771.It Xo 772.Fl o Ns Ar filename | 773.Fl -log-file Ns = Ns Ar filename 774.Xc 775Causes 776.Nm 777to copy its input to the named file as it is being viewed. 778This applies only when the input file is a pipe, not an ordinary file. 779If the file already exists, 780.Nm 781will ask for confirmation before overwriting it. 782.It Xo 783.Fl P Ns Ar prompt | 784.Fl -prompt Ns = Ns Ar prompt 785.Xc 786Provides a way to tailor the three prompt styles to your own preference. 787This option would normally be put in the 788.Ev LESS 789environment variable, rather than being typed in with each 790.Nm 791command. 792Such an option must either be the last option in the 793.Ev LESS 794variable, or be terminated by a dollar sign. 795-Ps followed by a string changes the default (short) prompt to that string. 796-Pm changes the medium (-m) prompt. 797-PM changes the long (-M) prompt. 798-Ph changes the prompt for the help screen. 799-P= changes the message printed by the = command. 800-Pw changes the message printed while waiting for data (in the F command). 801All prompt strings consist of a sequence of letters and special escape 802sequences. 803See the section on 804.Sx PROMPTS 805for more details. 806.It Xo 807.Fl p Ns Ar pattern | 808.Fl -pattern Ns = Ns Ar pattern 809.Xc 810The -p option on the command line is equivalent to specifying +/pattern; 811that is, it tells 812.Nm 813to start at the first occurrence of pattern in the file. 814.It Fl Q | -QUIET | -SILENT 815Causes totally "quiet" operation: the terminal bell is never rung. 816.It Fl q | -quiet | -silent 817Causes moderately "quiet" operation: 818the terminal bell is not rung if an attempt is made to scroll past the end 819of the file or before the beginning of the file. 820If the terminal has a "visual bell", it is used instead. 821The bell will be rung on certain other errors, 822such as typing an invalid character. 823The default is to ring the terminal bell in all such cases. 824.It Fl R | -RAW-CONTROL-CHARS 825Like -r, but only ANSI "color" escape sequences are output in "raw" form. 826Unlike -r, the screen appearance is maintained correctly in most cases. 827ANSI "color" escape sequences are sequences of the form: 828.Pp 829.Dl ESC \&[ ... m 830.Pp 831where the "..." is zero or more color specification characters. 832For the purpose of keeping track of screen appearance, 833ANSI color escape sequences are assumed to not move the cursor. 834You can make 835.Nm 836think that characters other than "m" can end ANSI color escape sequences 837by setting the environment variable 838.Ev LESSANSIENDCHARS 839to the list of characters which can end a color escape sequence. 840And you can make 841.Nm 842think that characters other than the standard ones may appear between 843the ESC and the m by setting the environment variable 844.Ev LESSANSIMIDCHARS 845to the list of characters which can appear. 846.It Fl r | -raw-control-chars 847Causes "raw" control characters to be displayed. 848The default is to display control characters using the caret notation; 849for example, a control-A (octal 001) is displayed as "^A". 850Warning: when the -r option is used, 851.Nm 852cannot keep track of the actual appearance of the screen 853(since this depends on how the screen responds to 854each type of control character). 855Thus, various display problems may result, 856such as long lines being split in the wrong place. 857.It Fl S | -chop-long-lines 858Causes lines longer than the screen width to be chopped rather than folded. 859That is, the portion of a long line that does not fit in 860the screen width is not shown. 861The default is to fold long lines; that is, display the remainder 862on the next line. 863.It Fl s | -squeeze-blank-lines 864Causes consecutive blank lines to be squeezed into a single blank line. 865.It Xo 866.Fl T Ns Ar tagsfile | 867.Fl -tag-file Ns = Ns Ar tagsfile 868.Xc 869Specifies a tags file to be used instead of "tags". 870.It Xo 871.Fl t Ns Ar tag | 872.Fl -tag Ns = Ns Ar tag 873.Xc 874The -t option, followed immediately by a TAG, 875will edit the file containing that tag. 876For this to work, tag information must be available; 877for example, there may be a file in the current directory called "tags", 878which was previously built by 879.Xr ctags 1 880or an equivalent command. 881If the environment variable 882.Ev LESSGLOBALTAGS 883is set, it is taken to be the name of a command compatible with 884.Xr global , 885and that command is executed to find the tag. 886(See http://www.gnu.org/software/global/global.html). 887The -t option may also be specified from within 888.Nm 889(using the \- command) as a way of examining a new file. 890The command ":t" is equivalent to specifying -t from within 891.Nm less . 892.It Fl U | -UNDERLINE-SPECIAL 893Causes backspaces, tabs and carriage returns to be 894treated as control characters; 895that is, they are handled as specified by the -r option. 896.Pp 897By default, if neither -u nor -U is given, backspaces which appear adjacent 898to an underscore character are treated specially: 899the underlined text is displayed 900using the terminal's hardware underlining capability. 901Also, backspaces which appear between two identical characters 902are treated specially: 903the overstruck text is printed 904using the terminal's hardware boldface capability. 905Other backspaces are deleted, along with the preceding character. 906Carriage returns immediately followed by a newline are deleted. 907Other carriage returns are handled as specified by the -r option. 908Text which is overstruck or underlined can be searched for 909if neither -u nor -U is in effect. 910.It Fl u | -underline-special 911Causes backspaces and carriage returns to be treated as printable characters; 912that is, they are sent to the terminal when they appear in the input. 913.It Fl V | -version 914Displays the version number of 915.Nm less . 916.It Fl W | -HILITE-UNREAD 917Like -w, but temporarily highlights the first new line after any 918forward movement command larger than one line. 919.It Fl w | -hilite-unread 920Temporarily highlights the first "new" line after a forward movement 921of a full page. 922The first "new" line is the line immediately following the line previously 923at the bottom of the screen. 924Also highlights the target line after a g or p command. 925The highlight is removed at the next command which causes movement. 926The entire line is highlighted, unless the -J option is in effect, 927in which case only the status column is highlighted. 928.It Fl X | -no-init 929Disables sending the termcap initialization and deinitialization strings 930to the terminal. 931This is sometimes desirable if the deinitialization string does 932something unnecessary, like clearing the screen. 933.It Xo 934.Fl x Ns Ar n,... | 935.Fl -tabs Ns = Ns Ar n,... 936.Xc 937Sets tab stops. 938If only one n is specified, tab stops are set at multiples of n. 939If multiple values separated by commas are specified, tab stops are set at 940those positions, and then continue with the same spacing as the last two. 941For example, -x9,17 will set tabs at positions 9, 17, 25, 33, etc. 942The default for n is 8. 943.It Xo 944.Fl y Ns Ar n | 945.Fl -max-forw-scroll Ns = Ns Ar n 946.Xc 947Specifies a maximum number of lines to scroll forward. 948If it is necessary to scroll forward more than n lines, 949the screen is repainted instead. 950The -c or -C option may be used to repaint from the top of 951the screen if desired. 952By default, any forward movement causes scrolling. 953.It Xo 954.Fl Oo Cm z Oc Ns Ar n | 955.Fl -window Ns = Ns Ar n 956.Xc 957Changes the default scrolling window size to n lines. 958The default is one screenful. 959The z and w commands can also be used to change the window size. 960The "z" may be omitted for compatibility with some versions of 961.Nm more . 962If the number 963.Ar n 964is negative, it indicates 965.Ar n 966lines less than the current screen size. 967For example, if the screen is 24 lines, -z-4 sets the 968scrolling window to 20 lines. 969If the screen is resized to 40 lines, 970the scrolling window automatically changes to 36 lines. 971.It Fl -follow-name 972Normally, if the input file is renamed while an F command is executing, 973.Nm 974will continue to display the contents of the original file despite 975its name change. 976If --follow-name is specified, during an F command 977.Nm 978will periodically attempt to reopen the file by name. 979If the reopen succeeds and the file is a different file from the original 980(which means that a new file has been created 981with the same name as the original (now renamed) file), 982.Nm 983will display the contents of that new file. 984.It Fl -no-keypad 985Disables sending the keypad initialization and deinitialization strings 986to the terminal. 987This is sometimes useful if the keypad strings make the numeric 988keypad behave in an undesirable manner. 989.It Xo 990.Ar -cc | 991.Fl -quotes Ns = Ns Ar cc 992.Xc 993Changes the filename quoting character. 994This may be necessary if you are trying to name a file 995which contains both spaces and quote characters. 996Followed by a single character, this changes the quote character to that 997character. 998Filenames containing a space should then be surrounded by that character 999rather than by double quotes. 1000Followed by two characters, changes the open quote to the first character, 1001and the close quote to the second character. 1002Filenames containing a space should then be preceded by the open quote 1003character and followed by the close quote character. 1004Note that even after the quote characters are changed, this option 1005remains -" (a dash followed by a double quote). 1006.It Fl ~ | -tilde 1007Normally lines after end of file are displayed as a single tilde (~). 1008This option causes lines after end of file to be displayed as blank lines. 1009.It Fl # | -shift 1010Specifies the default number of positions to scroll horizontally 1011in the RIGHTARROW and LEFTARROW commands. 1012If the number specified is zero, it sets the default number of 1013positions to one half of the screen width. 1014Alternately, the number may be specified as a fraction of the width 1015of the screen, starting with a decimal point: .5 is half of the 1016screen width, .3 is three tenths of the screen width, and so on. 1017If the number is specified as a fraction, the actual number of 1018scroll positions is recalculated if the terminal window is resized, 1019so that the actual scroll remains at the specified fraction 1020of the screen width. 1021.It Fl - 1022A command line argument of "--" marks the end of option arguments. 1023Any arguments following this are interpreted as filenames. 1024This can be useful when viewing a file whose name begins with a "-" or "+". 1025.It Cm + 1026If a command line option begins with +, 1027the remainder of that option is taken to be an initial command to 1028.Nm less . 1029For example, +G tells 1030.Nm 1031to start at the end of the file rather than the beginning, 1032and +/xyz tells it to start at the first occurrence of "xyz" in the file. 1033As a special case, +<number> acts like +<number>g; 1034that is, it starts the display at the specified line number 1035(however, see the caveat under the "g" command above). 1036If the option starts with ++, the initial command applies to 1037every file being viewed, not just the first one. 1038The + command described previously 1039may also be used to set (or change) an initial command for every file. 1040.El 1041.Sh LINE EDITING 1042When entering command line at the bottom of the screen 1043(for example, a filename for the :e command, 1044or the pattern for a search command), 1045certain keys can be used to manipulate the command line. 1046Most commands have an alternate form in [ brackets ] which can be used if 1047a key does not exist on a particular keyboard. 1048.\" (Note that the forms beginning with ESC do not work 1049.\" in some MS-DOS and Windows systems because ESC is the line erase character.) 1050Any of these special keys may be entered literally by preceding 1051it with the "literal" character, either ^V or ^A. 1052A backslash itself may also be entered literally by entering two backslashes. 1053.Bl -tag -width Ds 1054.It LEFTARROW [ ESC-h ] 1055Move the cursor one space to the left. 1056.It RIGHTARROW [ ESC-l ] 1057Move the cursor one space to the right. 1058.It ^LEFTARROW [ ESC-b or ESC-LEFTARROW ] 1059(That is, CONTROL and LEFTARROW simultaneously.) 1060Move the cursor one word to the left. 1061.It ^RIGHTARROW [ ESC-w or ESC-RIGHTARROW ] 1062(That is, CONTROL and RIGHTARROW simultaneously.) 1063Move the cursor one word to the right. 1064.It HOME [ ESC-0 ] 1065Move the cursor to the beginning of the line. 1066.It END [ ESC-$ ] 1067Move the cursor to the end of the line. 1068.It BACKSPACE 1069Delete the character to the left of the cursor, 1070or cancel the command if the command line is empty. 1071.It DELETE or [ ESC-x ] 1072Delete the character under the cursor. 1073.It ^BACKSPACE [ ESC-BACKSPACE ] 1074(That is, CONTROL and BACKSPACE simultaneously.) 1075Delete the word to the left of the cursor. 1076.It ^DELETE [ ESC-X or ESC-DELETE ] 1077(That is, CONTROL and DELETE simultaneously.) 1078Delete the word under the cursor. 1079.It UPARROW [ ESC-k ] 1080Retrieve the previous command line. 1081.It DOWNARROW [ ESC-j ] 1082Retrieve the next command line. 1083.It TAB 1084Complete the partial filename to the left of the cursor. 1085If it matches more than one filename, the first match 1086is entered into the command line. 1087Repeated TABs will cycle through the other matching filenames. 1088If the completed filename is a directory, a "/" is appended to the filename. 1089.\" (On MS-DOS systems, a "\e" is appended.) 1090The environment variable 1091.Ev LESSSEPARATOR 1092can be used to specify a different character to append to a directory name. 1093.It BACKTAB [ ESC-TAB ] 1094Like TAB, but cycles in the reverse direction through the matching filenames. 1095.It ^L 1096Complete the partial filename to the left of the cursor. 1097If it matches more than one filename, all matches are entered into 1098the command line (if they fit). 1099.\" .It ^U (Unix and OS/2) or ESC (MS-DOS) 1100.It ^U 1101Delete the entire command line, 1102or cancel the command if the command line is empty. 1103If you have changed your line-kill character to something 1104other than ^U, that character is used instead of ^U. 1105.It "^G" 1106Delete the entire command line and return to the main prompt. 1107.El 1108.Sh KEY BINDINGS 1109You may define your own 1110.Nm 1111commands by using the program 1112.Xr lesskey 1 1113to create a lesskey file. 1114This file specifies a set of command keys and an action 1115associated with each key. 1116You may also use lesskey 1117to change the line-editing keys (see 1118.Sx LINE EDITING ) , 1119and to set environment variables. 1120If the environment variable 1121.Ev LESSKEY 1122is set, 1123.Nm 1124uses that as the name of the lesskey file. 1125Otherwise, 1126.Nm 1127looks for a lesskey file called "$HOME/.less". 1128.\" On MS-DOS and Windows systems, 1129.\" .I less 1130.\" looks for a lesskey file called "$HOME/_less", and if it is not found there, 1131.\" then looks for a lesskey file called "_less" in any directory specified 1132.\" in the PATH environment variable. 1133.\" On OS/2 systems, 1134.\" .I less 1135.\" looks for a lesskey file called "$HOME/less.ini", and if it is not found, 1136.\" then looks for a lesskey file called "less.ini" in any directory specified 1137.\" in the INIT environment variable, and if it not found there, 1138.\" then looks for a lesskey file called "less.ini" in any directory specified 1139.\" in the PATH environment variable. 1140See the 1141.Xr lesskey 1 1142manual page for more details. 1143.Pp 1144A system-wide lesskey file may also be set up to provide key bindings. 1145If a key is defined in both a local lesskey file and in the 1146system-wide file, key bindings in the local file take precedence over 1147those in the system-wide file. 1148If the environment variable 1149.Ev LESSKEY_SYSTEM 1150is set, 1151.Nm 1152uses that as the name of the system-wide lesskey file. 1153Otherwise, 1154.Nm 1155looks in a standard place for the system-wide lesskey file: 1156On 1157.Ox , 1158the system-wide lesskey file is 1159.Pa /etc/sysless . 1160.\" On Unix systems, the system-wide lesskey file is /usr/local/etc/sysless. 1161.\" (However, if 1162.\" .Nm less 1163.\" was built with a different sysconf directory than /usr/local/etc, 1164.\" that directory is where the sysless file is found.) 1165.\" On MS-DOS and Windows systems, the system-wide lesskey file is c:\e_sysless. 1166.\" On OS/2 systems, the system-wide lesskey file is c:\esysless.ini. 1167.Sh INPUT PREPROCESSOR 1168You may define an "input preprocessor" for 1169.Nm less . 1170Before 1171.Nm less 1172opens a file, it first gives your input preprocessor a chance to modify the 1173way the contents of the file are displayed. 1174An input preprocessor is simply an executable program (or shell script), 1175which writes the contents of the file to a different file, 1176called the replacement file. 1177The contents of the replacement file are then displayed 1178in place of the contents of the original file. 1179However, it will appear to the user as if the original file is opened; 1180that is, 1181.Nm less 1182will display the original filename as the name of the current file. 1183.Pp 1184An input preprocessor receives one command line argument, the original filename, 1185as entered by the user. 1186It should create the replacement file, and when finished 1187print the name of the replacement file to its standard output. 1188If the input preprocessor does not output a replacement filename, 1189.Nm 1190uses the original file, as normal. 1191The input preprocessor is not called when viewing standard input. 1192To set up an input preprocessor, set the 1193.Ev LESSOPEN 1194environment variable to a command line which will invoke your 1195input preprocessor. 1196This command line should include one occurrence of the string "%s", 1197which will be replaced by the filename 1198when the input preprocessor command is invoked. 1199.Pp 1200When 1201.Nm 1202closes a file opened in such a way, it will call another program, 1203called the input postprocessor, 1204which may perform any desired clean-up action (such as deleting the 1205replacement file created by 1206.Ev LESSOPEN ) . 1207This program receives two command line arguments, the original filename 1208as entered by the user, and the name of the replacement file. 1209To set up an input postprocessor, set the 1210.Ev LESSCLOSE 1211environment variable to a command line which will invoke your 1212input postprocessor. 1213It may include two occurrences of the string "%s"; 1214the first is replaced with the original name of the file and the second 1215with the name of the replacement file, which was output by 1216.Ev LESSOPEN . 1217.Pp 1218For example, these two scripts will allow you 1219to keep files in compressed format, but still let 1220.Nm 1221view them directly: 1222.Pp 1223lessopen.sh: 1224.Bd -literal -offset indent 1225#! /bin/sh 1226case "$1" in 1227*.Z) uncompress -c $1 >/tmp/less.$$ 2>/dev/null 1228 if [ -s /tmp/less.$$ ]; then 1229 echo /tmp/less.$$ 1230 else 1231 rm -f /tmp/less.$$ 1232 fi 1233 ;; 1234esac 1235.Ed 1236.Pp 1237lessclose.sh: 1238.Bd -literal -offset indent 1239#! /bin/sh 1240rm $2 1241.Ed 1242.Pp 1243To use these scripts, put them both where they can be executed and 1244set LESSOPEN="lessopen.sh\ %s", and LESSCLOSE="lessclose.sh\ %s\ %s". 1245More complex LESSOPEN and LESSCLOSE scripts may be written 1246to accept other types of compressed files, and so on. 1247.Pp 1248It is also possible to set up an input preprocessor to 1249pipe the file data directly to 1250.Nm less , 1251rather than putting the data into a replacement file. 1252This avoids the need to decompress the entire file before starting to view it. 1253An input preprocessor that works this way is called an input pipe. 1254An input pipe, instead of writing the name of a replacement file on 1255its standard output, 1256writes the entire contents of the replacement file on its standard output. 1257If the input pipe does not write any characters on its standard output, 1258then there is no replacement file and 1259.Nm 1260uses the original file, as normal. 1261To use an input pipe, make the first character in the 1262.Ev LESSOPEN 1263environment variable a vertical bar (|) to signify that the 1264input preprocessor is an input pipe. 1265.Pp 1266For example, this script will work like the previous example scripts: 1267.Pp 1268lesspipe.sh: 1269.Bd -literal -offset indent 1270#! /bin/sh 1271case "$1" in 1272*.Z) uncompress -c $1 2>/dev/null 1273 ;; 1274esac 1275.Ed 1276.Pp 1277To use this script, put it where it can be executed and set 1278LESSOPEN="|lesspipe.sh %s". 1279When an input pipe is used, a LESSCLOSE postprocessor can be used, 1280but it is usually not necessary since there is no replacement file to clean up. 1281In this case, the replacement file name passed to the LESSCLOSE 1282postprocessor is "-". 1283.Pp 1284For compatibility with previous versions of 1285.Nm less , 1286the input preprocessor or pipe is not used if 1287.Nm 1288is viewing standard input. 1289However, if the first character of LESSOPEN is a dash (-), 1290the input preprocessor is used on standard input as well as other files. 1291In this case, the dash is not considered to be part of 1292the preprocessor command. 1293If standard input is being viewed, the input preprocessor is passed 1294a file name consisting of a single dash. 1295Similarly, if the first two characters of LESSOPEN are vertical bar and dash 1296(|-), the input pipe is used on standard input as well as other files. 1297Again, in this case the dash is not considered to be part of 1298the input pipe command. 1299.Sh NATIONAL CHARACTER SETS 1300There are three types of characters in the input file: 1301.Bl -tag -width "control characters" 1302.It normal characters 1303Can be displayed directly to the screen. 1304.It control characters 1305Should not be displayed directly, but are expected to be found 1306in ordinary text files (such as backspace and tab). 1307.It binary characters 1308Should not be displayed directly and are not expected to be found 1309in text files. 1310.El 1311.Pp 1312A "character set" is simply a description of which characters are to 1313be considered normal, control, and binary. 1314The 1315.Ev LESSCHARSET 1316environment variable may be used to select a character set. 1317Possible values for 1318.Ev LESSCHARSET 1319are: 1320.Bl -tag -width "IBM-1047" 1321.It ascii 1322BS, TAB, NL, CR, and formfeed are control characters, 1323all chars with values between 32 and 126 are normal, 1324and all others are binary. 1325.It iso8859 1326Selects an ISO 8859 character set. 1327This is the same as ASCII, except characters between 160 and 255 are 1328treated as normal characters. 1329.It latin1 1330Same as iso8859. 1331.It latin9 1332Same as iso8859. 1333.It dos 1334Selects a character set appropriate for MS-DOS. 1335.It ebcdic 1336Selects an EBCDIC character set. 1337.It IBM-1047 1338Selects an EBCDIC character set used by OS/390 1339.Ux 1340Services. 1341This is the EBCDIC analogue of latin1. 1342You get similar results by setting either LESSCHARSET=IBM-1047 or 1343LC_CTYPE=en_US in your environment. 1344.It koi8-r 1345Selects a Russian character set. 1346.It next 1347Selects a character set appropriate for NeXT computers. 1348.It utf-8 1349Selects the UTF-8 encoding of the ISO 10646 character set. 1350UTF-8 is special in that it supports multi-byte characters in the input file. 1351It is the only character set that supports multi-byte characters. 1352.It windows 1353Selects a character set appropriate for Microsoft Windows (cp 1251). 1354.El 1355.Pp 1356In rare cases, it may be desired to tailor 1357.Nm 1358to use a character set other than the ones definable by LESSCHARSET. 1359In this case, the environment variable 1360.Ev LESSCHARDEF 1361can be used to define a character set. 1362It should be set to a string where each character in the string represents 1363one character in the character set. 1364The character "." is used for a normal character, "c" for control, 1365and "b" for binary. 1366A decimal number may be used for repetition. 1367For example, "bccc4b." would mean character 0 is binary, 13681, 2 and 3 are control, 4, 5, 6 and 7 are binary, and 8 is normal. 1369All characters after the last are taken to be the same as the last, 1370so characters 9 through 255 would be normal. 1371(This is an example, and does not necessarily 1372represent any real character set.) 1373.Pp 1374This table shows the value of LESSCHARDEF which is equivalent 1375to each of the possible values for LESSCHARSET: 1376.Bd -literal -offset indent 1377ascii 8bcccbcc18b95.b 1378dos 8bcccbcc12bc5b95.b. 1379ebcdic 5bc6bcc7bcc41b.9b7.9b5.b..8b6.10b6.b9.7b 1380 9.8b8.17b3.3b9.7b9.8b8.6b10.b.b.b. 1381IBM-1047 4cbcbc3b9cbccbccbb4c6bcc5b3cbbc4bc4bccbc 1382 191.b 1383iso8859 8bcccbcc18b95.33b. 1384koi8-r 8bcccbcc18b95.b128. 1385latin1 8bcccbcc18b95.33b. 1386next 8bcccbcc18b95.bb125.bb 1387.Ed 1388.Pp 1389If neither LESSCHARSET nor LESSCHARDEF is set, 1390but any of the strings "UTF-8", "UTF8", "utf-8" or "utf8" is found in the 1391.Ev LC_ALL , LC_CTYPE 1392or 1393.Ev LANG 1394environment variables, then the default character set is utf-8. 1395.Pp 1396If that string is not found, but your system supports the 1397setlocale interface, 1398.Nm 1399will use setlocale to determine the character set. 1400setlocale is controlled by setting the 1401.Ev LANG 1402or 1403.Ev LC_CTYPE 1404environment variables. 1405.Pp 1406Finally, if the 1407setlocale interface is also not available, the default character set is latin1. 1408.Pp 1409Control and binary characters are displayed in standout (reverse video). 1410Each such character is displayed in caret notation if possible 1411(e.g. ^A for control-A). 1412Caret notation is used only if inverting the 0100 bit results in a 1413normal printable character. 1414Otherwise, the character is displayed as a hex number in angle brackets. 1415This format can be changed by setting the 1416.Ev LESSBINFMT 1417environment variable. 1418LESSBINFMT may begin with a "*" and one character to select 1419the display attribute: 1420"*k" is blinking, "*d" is bold, "*u" is underlined, "*s" is standout, 1421and "*n" is normal. 1422If LESSBINFMT does not begin with a "*", normal attribute is assumed. 1423The remainder of LESSBINFMT is a string which may include one 1424printf-style escape sequence (a % followed by x, X, o, d, etc.). 1425For example, if LESSBINFMT is "*u[%x]", binary characters 1426are displayed in underlined hexadecimal surrounded by brackets. 1427The default if no LESSBINFMT is specified is "*s<%02X>". 1428Warning: the result of expanding the character via LESSBINFMT must 1429be less than 31 characters. 1430.Pp 1431When the character set is utf-8, the 1432.Ev LESSUTFBINFMT 1433environment variable 1434acts similarly to LESSBINFMT but it applies to Unicode code points 1435that were successfully decoded but are unsuitable for display (e.g., 1436unassigned code points). 1437Its default value is "<U+%04lX>". 1438Note that LESSUTFBINFMT and LESSBINFMT share their display attribute 1439setting ("*x") so specifying one will affect both; 1440LESSUTFBINFMT is read after LESSBINFMT so its setting, if any, 1441will have priority. 1442Problematic octets in a UTF-8 file (octets of a truncated sequence, 1443octets of a complete but non-shortest form sequence, illegal octets, 1444and stray trailing octets) 1445are displayed individually using LESSBINFMT so as to facilitate diagnostic 1446of how the UTF-8 file is ill-formed. 1447.Sh PROMPTS 1448The -P option allows you to tailor the prompt to your preference. 1449The string given to the -P option replaces the specified prompt string. 1450Certain characters in the string are interpreted specially. 1451The prompt mechanism is rather complicated to provide flexibility, 1452but the ordinary user need not understand the details of constructing 1453personalized prompt strings. 1454.Pp 1455A percent sign followed by a single character is expanded 1456according to what the following character is: 1457.Bl -tag -width Ds 1458.It %b Ns Ar X 1459Replaced by the byte offset into the current input file. 1460The b is followed by a single character (shown as 1461.Ar X 1462above) which specifies the line whose byte offset is to be used. 1463If the character is a "t", the byte offset of the top line in the 1464display is used, 1465an "m" means use the middle line, 1466a "b" means use the bottom line, 1467a "B" means use the line just after the bottom line, 1468and a "j" means use the "target" line, as specified by the -j option. 1469.It \&%B 1470Replaced by the size of the current input file. 1471.It %c 1472Replaced by the column number of the text appearing in the first 1473column of the screen. 1474.It %d Ns Ar X 1475Replaced by the page number of a line in the input file. 1476The line to be used is determined by the 1477.Ar X , 1478as with the %b option. 1479.It \&%D 1480Replaced by the number of pages in the input file, 1481or equivalently, the page number of the last line in the input file. 1482.It %E 1483Replaced by the name of the editor (from the 1484.Ev VISUAL 1485environment variable, or the 1486.Ev EDITOR 1487environment variable if 1488.Ev VISUAL 1489is not defined). 1490See the discussion of the LESSEDIT feature below. 1491.It %f 1492Replaced by the name of the current input file. 1493.It %F 1494Replaced by the last component of the name of the current input file. 1495.It %i 1496Replaced by the index of the current file in the list of 1497input files. 1498.It %l Ns Ar X 1499Replaced by the line number of a line in the input file. 1500The line to be used is determined by the 1501.Ar X , 1502as with the %b option. 1503.It %L 1504Replaced by the line number of the last line in the input file. 1505.It %m 1506Replaced by the total number of input files. 1507.It %p Ns Ar X 1508Replaced by the percent into the current input file, based on byte offsets. 1509The line used is determined by the 1510.Ar X , 1511as with the %b option. 1512.It \&%P Ns Ar X 1513Replaced by the percent into the current input file, based on line numbers. 1514The line used is determined by the 1515.Ar X , 1516as with the %b option. 1517.It %s 1518Same as %B. 1519.It %t 1520Causes any trailing spaces to be removed. 1521Usually used at the end of the string, but may appear anywhere. 1522.It %x 1523Replaced by the name of the next input file in the list. 1524.El 1525.Pp 1526If any item is unknown (for example, the file size if input is a pipe), 1527a question mark is printed instead. 1528.Pp 1529The format of the prompt string can be changed depending on certain conditions. 1530A question mark followed by a single character acts like an "IF": 1531depending on the following character, a condition is evaluated. 1532If the condition is true, any characters following the question mark 1533and condition character, up to a period, are included in the prompt. 1534If the condition is false, such characters are not included. 1535A colon appearing between the question mark and the 1536period can be used to establish an "ELSE": any characters between 1537the colon and the period are included in the string, if and only if 1538the IF condition is false. 1539Condition characters (which follow a question mark) may be: 1540.Bl -tag -width Ds 1541.It ?a 1542True if any characters have been included in the prompt so far. 1543.It ?b Ns Ar X 1544True if the byte offset of the specified line is known. 1545.It ?B 1546True if the size of the current input file is known. 1547.It ?c 1548True if the text is horizontally shifted (%c is not zero). 1549.It ?d Ns Ar X 1550True if the page number of the specified line is known. 1551.It ?e 1552True if at end-of-file. 1553.It ?f 1554True if there is an input filename 1555(that is, if input is not a pipe). 1556.It ?l Ns Ar X 1557True if the line number of the specified line is known. 1558.It ?L 1559True if the line number of the last line in the file is known. 1560.It ?m 1561True if there is more than one input file. 1562.It ?n 1563True if this is the first prompt in a new input file. 1564.It ?p Ns Ar X 1565True if the percent into the current input file, based on byte offsets, 1566of the specified line is known. 1567.It ?P Ns Ar X 1568True if the percent into the current input file, based on line numbers, 1569of the specified line is known. 1570.It ?s 1571Same as "?B". 1572.It ?x 1573True if there is a next input file 1574(that is, if the current input file is not the last one). 1575.El 1576.Pp 1577Any characters other than the special ones 1578(question mark, colon, period, percent, and backslash) 1579become literally part of the prompt. 1580Any of the special characters may be included in the prompt literally 1581by preceding it with a backslash. 1582.Pp 1583Some examples: 1584.Pp 1585.Dl ?f%f:Standard input. 1586.Pp 1587This prompt prints the filename, if known; 1588otherwise the string "Standard input". 1589.Pp 1590.Dl ?f%f .?ltLine %lt:?pt%pt\e%:?btByte %bt:-... 1591.Pp 1592This prompt would print the filename, if known. 1593The filename is followed by the line number, if known, 1594otherwise the percent if known, otherwise the byte offset if known. 1595Otherwise, a dash is printed. 1596Notice how each question mark has a matching period, 1597and how the % after the %pt 1598is included literally by escaping it with a backslash. 1599.Pp 1600.Dl ?n?f%f\ .?m(file\ %i\ of\ %m)\ ..?e(END)\ ?x-\ Next\e:\ %x..%t 1601.Pp 1602This prints the filename if this is the first prompt in a file, 1603followed by the "file N of N" message if there is more 1604than one input file. 1605Then, if we are at end-of-file, the string "(END)" is printed 1606followed by the name of the next file, if there is one. 1607Finally, any trailing spaces are truncated. 1608This is the default prompt. 1609For reference, here are the defaults for 1610the other two prompts (-m and -M respectively). 1611Each is broken into two lines here for readability only. 1612.Bd -literal -offset indent 1613?f%f\ .?m(file\ %i\ of\ %m)\ .?e(END)\ ?x-\ Next\e:\ %x.: 1614 ?pB%pB\e%:byte\ %bB?s/%s...%t 1615 1616?f%f\ .?n?m(file\ %i\ of\ %m)\ ..?ltlines\ %lt-%lb?L/%L.\ : 1617 byte\ %bB?s/%s.\ .?e(END)\ ?x-\ Next\e:\ %x.:?pB%pB\e%..%t 1618.Ed 1619.Pp 1620And here is the default message produced by the = command: 1621.Bd -literal -offset indent 1622?f%f\ .?m(file\ %i\ of\ %m)\ .?ltlines\ %lt-%lb?L/%L.\ . 1623 byte\ %bB?s/%s.\ ?e(END)\ :?pB%pB\e%..%t 1624.Ed 1625.Pp 1626The prompt expansion features are also used for another purpose: 1627if an environment variable 1628.Ev LESSEDIT 1629is defined, it is used as the command to be executed when the v command 1630is invoked. 1631The LESSEDIT string is expanded in the same way as the prompt strings. 1632The default value for LESSEDIT is: 1633.Pp 1634.Dl %E\ ?lm+%lm.\ %f 1635.Pp 1636Note that this expands to the editor name, followed by a + and the 1637line number, followed by the file name. 1638If your editor does not accept the "+linenumber" syntax, or has other 1639differences in invocation syntax, the 1640.Ev LESSEDIT 1641variable can be changed to modify this default. 1642.Sh SECURITY 1643When the environment variable 1644.Ev LESSSECURE 1645is set to 1, 1646.Nm 1647runs in a "secure" mode. 1648This means these features are disabled: 1649.Bl -tag -width Ds 1650.It \&! 1651The shell command. 1652.It | 1653The pipe command. 1654.It :e 1655The examine command. 1656.It v 1657The editing command. 1658.It s -o 1659Log files. 1660.It -k 1661Use of lesskey files. 1662.It -t 1663Use of tags files. 1664.It " " 1665Metacharacters in filenames, such as "*". 1666.It " " 1667Filename completion (TAB, ^L). 1668.El 1669.Pp 1670Less can also be compiled to be permanently in "secure" mode. 1671.Sh COMPATIBILITY WITH MORE 1672If the environment variable 1673.Ev LESS_IS_MORE 1674is set to 1, 1675or if the program is invoked via a file link named "more", 1676.Nm 1677behaves (mostly) in conformance with the POSIX "more" command specification. 1678In this mode, less behaves differently in these ways: 1679.Pp 1680The -e option works differently. 1681If the -e option is not set, 1682.Nm 1683behaves as if the -E option were set. 1684If the -e option is set, 1685.Nm 1686behaves as if the -e and -F options were set. 1687.Pp 1688The -m option works differently. 1689If the -m option is not set, the medium prompt is used. 1690If the -m option is set, the short prompt is used. 1691.Pp 1692The -n option acts like the -z option. 1693The normal behavior of the -n option is unavailable in this mode. 1694.Pp 1695The parameter to the -p option is taken to be a 1696.Nm 1697command rather than a search pattern. 1698.Pp 1699The 1700.Ev LESS 1701environment variable is ignored, and the 1702.Ev MORE 1703environment variable is used in its place. 1704.Sh ENVIRONMENT 1705Environment variables may be specified either in the system environment 1706as usual, or in a 1707.Xr lesskey 1 1708file. 1709If environment variables are defined in more than one place, 1710variables defined in a local lesskey file take precedence over 1711variables defined in the system environment, which take precedence 1712over variables defined in the system-wide lesskey file. 1713.Bl -tag -width Ds 1714.It Ev COLUMNS 1715Sets the number of columns on the screen. 1716Takes precedence over the number of columns specified by the TERM variable. 1717(But if you have a windowing system which supports TIOCGWINSZ or WIOCGETD, 1718the window system's idea of the screen size takes precedence over the 1719LINES and COLUMNS environment variables.) 1720.It Ev EDITOR 1721The name of the editor (used for the v command). 1722.It Ev HOME 1723Name of the user's home directory 1724(used to find a lesskey file). 1725.\" .It Ev "HOMEDRIVE, HOMEPATH" 1726.\" Concatenation of the HOMEDRIVE and HOMEPATH environment variables is 1727.\" the name of the user's home directory if the HOME variable is not set 1728.\" (only in the Windows version). 1729.\" .It Ev INIT 1730.\" Name of the user's init directory 1731.\" (used to find a lesskey file on OS/2 systems). 1732.It Ev LANG 1733Language for determining the character set. 1734.It Ev LC_CTYPE 1735Language for determining the character set. 1736.It Ev LESS 1737Options which are passed to 1738.Nm 1739automatically. 1740.It Ev LESSANSIENDCHARS 1741Characters which may end an ANSI color escape sequence 1742(default "m"). 1743.It Ev LESSANSIMIDCHARS 1744Characters which may appear between the ESC character and the 1745end character in an ANSI color escape sequence 1746(default "0123456789;[?!"'#%()*+\ "). 1747.It Ev LESSBINFMT 1748Format for displaying non-printable, non-control characters. 1749.It Ev LESSCHARDEF 1750Defines a character set. 1751.It Ev LESSCHARSET 1752Selects a predefined character set. 1753.It Ev LESSCLOSE 1754Command line to invoke the (optional) input-postprocessor. 1755.\" .It Ev LESSECHO 1756.\" Name of the lessecho program (default "lessecho"). 1757.\" The lessecho program is needed to expand metacharacters, such as * and ?, 1758.\" in filenames on Unix systems. 1759.It Ev LESSEDIT 1760Editor prototype string (used for the v command). 1761See discussion under 1762.Sx PROMPTS . 1763.It Ev LESSGLOBALTAGS 1764Name of the command used by the -t option to find global tags. 1765Normally should be set to "global" if your system has the global command. 1766If not set, global tags are not used. 1767.It Ev LESSHISTFILE 1768Name of the history file used to remember search commands and 1769shell commands between invocations of 1770.Nm less . 1771If set to "-" or "/dev/null", a history file is not used. 1772The default is "-". 1773.\" The default is "$HOME/.lesshst" on Unix systems, "$HOME/_lesshst" on 1774.\" DOS and Windows systems, or "$HOME/lesshst.ini" or "$INIT/lesshst.ini" 1775.\" on OS/2 systems. 1776.It Ev LESSHISTSIZE 1777The maximum number of commands to save in the history file. 1778The default is 100. 1779.It Ev LESSKEY 1780Name of the default lesskey(1) file. 1781.It Ev LESSKEY_SYSTEM 1782Name of the default system-wide lesskey(1) file. 1783.It Ev LESSMETACHARS 1784List of characters which are considered "metacharacters" by the shell. 1785.It Ev LESSMETAESCAPE 1786Prefix which 1787.Nm 1788will add before each metacharacter in a command sent to the shell. 1789If LESSMETAESCAPE is an empty string, commands containing 1790metacharacters will not be passed to the shell. 1791.It Ev LESSOPEN 1792Command line to invoke the (optional) input-preprocessor. 1793.It Ev LESSSECURE 1794Runs less in "secure" mode. 1795See discussion under 1796.Sx SECURITY . 1797.It Ev LESSSEPARATOR 1798String to be appended to a directory name in filename completion. 1799.It Ev LESSUTFBINFMT 1800Format for displaying non-printable Unicode code points. 1801.It Ev LESS_IS_MORE 1802Emulate the 1803.Xr more 1 1804command. 1805.It Ev LINES 1806Sets the number of lines on the screen. 1807Takes precedence over the number of lines specified by the TERM variable. 1808(But if you have a windowing system which supports TIOCGWINSZ or WIOCGETD, 1809the window system's idea of the screen size takes precedence over the 1810LINES and COLUMNS environment variables.) 1811.\" .It Ev PATH 1812.\" User's search path (used to find a lesskey file 1813.\" on MS-DOS and OS/2 systems). 1814.It Ev SHELL 1815The shell used to execute the ! command, as well as to expand filenames. 1816.It Ev TERM 1817The type of terminal on which 1818.Nm 1819is being run. 1820.It Ev VISUAL 1821The name of the editor (used for the v command). 1822.El 1823.Sh SEE ALSO 1824.Xr lesskey 1 1825.Sh STANDARDS 1826The 1827.Nm more 1828utility is compliant with the 1829.St -p1003.1-2008 1830specification, 1831though its presence is optional. 1832.Pp 1833The flags 1834.Op Fl aBbCdEFfGghIJjkLMmNOoPQqRrSTUVWwXxyz~# 1835are extensions to that specification. 1836.Sh AUTHORS 1837.An Mark Nudelman Aq markn@greenwoodsoftware.com 1838.Pp 1839Send bug reports or comments to the above address or to 1840.Aq bug\-less@gnu.org . 1841.Pp 1842For more information, see the less homepage at 1843.Pa http://www.greenwoodsoftware.com/less . 1844