less.man revision 161475
1LESS(1) LESS(1) 2 3 4 5NNAAMMEE 6 less - opposite of more 7 8SSYYNNOOPPSSIISS 9 lleessss --?? 10 lleessss ----hheellpp 11 lleessss --VV 12 lleessss ----vveerrssiioonn 13 lleessss [[--[[++]]aaBBccCCddeeEEffFFggGGiiIIJJKKLLmmMMnnNNqqQQrrRRssSSuuUUVVwwWWXX~~]] 14 [[--bb _s_p_a_c_e]] [[--hh _l_i_n_e_s]] [[--jj _l_i_n_e]] [[--kk _k_e_y_f_i_l_e]] 15 [[--{{ooOO}} _l_o_g_f_i_l_e]] [[--pp _p_a_t_t_e_r_n]] [[--PP _p_r_o_m_p_t]] [[--tt _t_a_g]] 16 [[--TT _t_a_g_s_f_i_l_e]] [[--xx _t_a_b,,......]] [[--yy _l_i_n_e_s]] [[--[[zz]] _l_i_n_e_s]] 17 [[--## _s_h_i_f_t]] [[++[[++]]_c_m_d]] [[----]] [[_f_i_l_e_n_a_m_e]]...... 18 (See the OPTIONS section for alternate option syntax with long option 19 names.) 20 21 22DDEESSCCRRIIPPTTIIOONN 23 _L_e_s_s is a program similar to _m_o_r_e (1), but which allows backward move- 24 ment in the file as well as forward movement. Also, _l_e_s_s does not have 25 to read the entire input file before starting, so with large input 26 files it starts up faster than text editors like _v_i (1). _L_e_s_s uses 27 termcap (or terminfo on some systems), so it can run on a variety of 28 terminals. There is even limited support for hardcopy terminals. (On 29 a hardcopy terminal, lines which should be printed at the top of the 30 screen are prefixed with a caret.) 31 32 Commands are based on both _m_o_r_e and _v_i_. Commands may be preceded by a 33 decimal number, called N in the descriptions below. The number is used 34 by some commands, as indicated. 35 36 37CCOOMMMMAANNDDSS 38 In the following descriptions, ^X means control-X. ESC stands for the 39 ESCAPE key; for example ESC-v means the two character sequence 40 "ESCAPE", then "v". 41 42 h or H Help: display a summary of these commands. If you forget all 43 the other commands, remember this one. 44 45 SPACE or ^V or f or ^F 46 Scroll forward N lines, default one window (see option -z 47 below). If N is more than the screen size, only the final 48 screenful is displayed. Warning: some systems use ^V as a spe- 49 cial literalization character. 50 51 z Like SPACE, but if N is specified, it becomes the new window 52 size. 53 54 ESC-SPACE 55 Like SPACE, but scrolls a full screenful, even if it reaches 56 end-of-file in the process. 57 58 RETURN or ^N or e or ^E or j or ^J 59 Scroll forward N lines, default 1. The entire N lines are dis- 60 played, even if N is more than the screen size. 61 62 d or ^D 63 Scroll forward N lines, default one half of the screen size. If 64 N is specified, it becomes the new default for subsequent d and 65 u commands. 66 67 b or ^B or ESC-v 68 Scroll backward N lines, default one window (see option -z 69 below). If N is more than the screen size, only the final 70 screenful is displayed. 71 72 w Like ESC-v, but if N is specified, it becomes the new window 73 size. 74 75 y or ^Y or ^P or k or ^K 76 Scroll backward N lines, default 1. The entire N lines are dis- 77 played, even if N is more than the screen size. Warning: some 78 systems use ^Y as a special job control character. 79 80 u or ^U 81 Scroll backward N lines, default one half of the screen size. 82 If N is specified, it becomes the new default for subsequent d 83 and u commands. 84 85 ESC-) or RIGHTARROW 86 Scroll horizontally right N characters, default half the screen 87 width (see the -# option). If a number N is specified, it 88 becomes the default for future RIGHTARROW and LEFTARROW com- 89 mands. While the text is scrolled, it acts as though the -S 90 option (chop lines) were in effect. 91 92 ESC-( or LEFTARROW 93 Scroll horizontally left N characters, default half the screen 94 width (see the -# option). If a number N is specified, it 95 becomes the default for future RIGHTARROW and LEFTARROW com- 96 mands. 97 98 r or ^R or ^L 99 Repaint the screen. 100 101 R Repaint the screen, discarding any buffered input. Useful if 102 the file is changing while it is being viewed. 103 104 F Scroll forward, and keep trying to read when the end of file is 105 reached. Normally this command would be used when already at 106 the end of the file. It is a way to monitor the tail of a file 107 which is growing while it is being viewed. (The behavior is 108 similar to the "tail -f" command.) 109 110 g or < or ESC-< 111 Go to line N in the file, default 1 (beginning of file). (Warn- 112 ing: this may be slow if N is large.) 113 114 G or > or ESC-> 115 Go to line N in the file, default the end of the file. (Warn- 116 ing: this may be slow if N is large, or if N is not specified 117 and standard input, rather than a file, is being read.) 118 119 p or % Go to a position N percent into the file. N should be between 0 120 and 100. 121 122 { If a left curly bracket appears in the top line displayed on the 123 screen, the { command will go to the matching right curly 124 bracket. The matching right curly bracket is positioned on the 125 bottom line of the screen. If there is more than one left curly 126 bracket on the top line, a number N may be used to specify the 127 N-th bracket on the line. 128 129 } If a right curly bracket appears in the bottom line displayed on 130 the screen, the } command will go to the matching left curly 131 bracket. The matching left curly bracket is positioned on the 132 top line of the screen. If there is more than one right curly 133 bracket on the top line, a number N may be used to specify the 134 N-th bracket on the line. 135 136 ( Like {, but applies to parentheses rather than curly brackets. 137 138 ) Like }, but applies to parentheses rather than curly brackets. 139 140 [ Like {, but applies to square brackets rather than curly brack- 141 ets. 142 143 ] Like }, but applies to square brackets rather than curly brack- 144 ets. 145 146 ESC-^F Followed by two characters, acts like {, but uses the two char- 147 acters as open and close brackets, respectively. For example, 148 "ESC ^F < >" could be used to go forward to the > which matches 149 the < in the top displayed line. 150 151 ESC-^B Followed by two characters, acts like }, but uses the two char- 152 acters as open and close brackets, respectively. For example, 153 "ESC ^B < >" could be used to go backward to the < which matches 154 the > in the bottom displayed line. 155 156 m Followed by any lowercase letter, marks the current position 157 with that letter. 158 159 ' (Single quote.) Followed by any lowercase letter, returns to 160 the position which was previously marked with that letter. Fol- 161 lowed by another single quote, returns to the position at which 162 the last "large" movement command was executed. Followed by a ^ 163 or $, jumps to the beginning or end of the file respectively. 164 Marks are preserved when a new file is examined, so the ' com- 165 mand can be used to switch between input files. 166 167 ^X^X Same as single quote. 168 169 /pattern 170 Search forward in the file for the N-th line containing the pat- 171 tern. N defaults to 1. The pattern is a regular expression, as 172 recognized by the regular expression library supplied by your 173 system. The search starts at the second line displayed (but see 174 the -a and -j options, which change this). 175 176 Certain characters are special if entered at the beginning of 177 the pattern; they modify the type of search rather than become 178 part of the pattern: 179 180 ^N or ! 181 Search for lines which do NOT match the pattern. 182 183 ^E or * 184 Search multiple files. That is, if the search reaches 185 the END of the current file without finding a match, the 186 search continues in the next file in the command line 187 list. 188 189 ^F or @ 190 Begin the search at the first line of the FIRST file in 191 the command line list, regardless of what is currently 192 displayed on the screen or the settings of the -a or -j 193 options. 194 195 ^K Highlight any text which matches the pattern on the cur- 196 rent screen, but don't move to the first match (KEEP cur- 197 rent position). 198 199 ^R Don't interpret regular expression metacharacters; that 200 is, do a simple textual comparison. 201 202 ?pattern 203 Search backward in the file for the N-th line containing the 204 pattern. The search starts at the line immediately before the 205 top line displayed. 206 207 Certain characters are special as in the / command: 208 209 ^N or ! 210 Search for lines which do NOT match the pattern. 211 212 ^E or * 213 Search multiple files. That is, if the search reaches 214 the beginning of the current file without finding a 215 match, the search continues in the previous file in the 216 command line list. 217 218 ^F or @ 219 Begin the search at the last line of the last file in the 220 command line list, regardless of what is currently dis- 221 played on the screen or the settings of the -a or -j 222 options. 223 224 ^K As in forward searches. 225 226 ^R As in forward searches. 227 228 ESC-/pattern 229 Same as "/*". 230 231 ESC-?pattern 232 Same as "?*". 233 234 n Repeat previous search, for N-th line containing the last pat- 235 tern. If the previous search was modified by ^N, the search is 236 made for the N-th line NOT containing the pattern. If the pre- 237 vious search was modified by ^E, the search continues in the 238 next (or previous) file if not satisfied in the current file. 239 If the previous search was modified by ^R, the search is done 240 without using regular expressions. There is no effect if the 241 previous search was modified by ^F or ^K. 242 243 N Repeat previous search, but in the reverse direction. 244 245 ESC-n Repeat previous search, but crossing file boundaries. The 246 effect is as if the previous search were modified by *. 247 248 ESC-N Repeat previous search, but in the reverse direction and cross- 249 ing file boundaries. 250 251 ESC-u Undo search highlighting. Turn off highlighting of strings 252 matching the current search pattern. If highlighting is already 253 off because of a previous ESC-u command, turn highlighting back 254 on. Any search command will also turn highlighting back on. 255 (Highlighting can also be disabled by toggling the -G option; in 256 that case search commands do not turn highlighting back on.) 257 258 :e [filename] 259 Examine a new file. If the filename is missing, the "current" 260 file (see the :n and :p commands below) from the list of files 261 in the command line is re-examined. A percent sign (%) in the 262 filename is replaced by the name of the current file. A pound 263 sign (#) is replaced by the name of the previously examined 264 file. However, two consecutive percent signs are simply 265 replaced with a single percent sign. This allows you to enter a 266 filename that contains a percent sign in the name. Similarly, 267 two consecutive pound signs are replaced with a single pound 268 sign. The filename is inserted into the command line list of 269 files so that it can be seen by subsequent :n and :p commands. 270 If the filename consists of several files, they are all inserted 271 into the list of files and the first one is examined. If the 272 filename contains one or more spaces, the entire filename should 273 be enclosed in double quotes (also see the -" option). 274 275 ^X^V or E 276 Same as :e. Warning: some systems use ^V as a special literal- 277 ization character. On such systems, you may not be able to use 278 ^V. 279 280 :n Examine the next file (from the list of files given in the com- 281 mand line). If a number N is specified, the N-th next file is 282 examined. 283 284 :p Examine the previous file in the command line list. If a number 285 N is specified, the N-th previous file is examined. 286 287 :x Examine the first file in the command line list. If a number N 288 is specified, the N-th file in the list is examined. 289 290 :d Remove the current file from the list of files. 291 292 t Go to the next tag, if there were more than one matches for the 293 current tag. See the -t option for more details about tags. 294 295 T Go to the previous tag, if there were more than one matches for 296 the current tag. 297 298 = or ^G or :f 299 Prints some information about the file being viewed, including 300 its name and the line number and byte offset of the bottom line 301 being displayed. If possible, it also prints the length of the 302 file, the number of lines in the file and the percent of the 303 file above the last displayed line. 304 305 - Followed by one of the command line option letters (see OPTIONS 306 below), this will change the setting of that option and print a 307 message describing the new setting. If a ^P (CONTROL-P) is 308 entered immediately after the dash, the setting of the option is 309 changed but no message is printed. If the option letter has a 310 numeric value (such as -b or -h), or a string value (such as -P 311 or -t), a new value may be entered after the option letter. If 312 no new value is entered, a message describing the current set- 313 ting is printed and nothing is changed. 314 315 -- Like the - command, but takes a long option name (see OPTIONS 316 below) rather than a single option letter. You must press 317 RETURN after typing the option name. A ^P immediately after the 318 second dash suppresses printing of a message describing the new 319 setting, as in the - command. 320 321 -+ Followed by one of the command line option letters this will 322 reset the option to its default setting and print a message 323 describing the new setting. (The "-+_X" command does the same 324 thing as "-+_X" on the command line.) This does not work for 325 string-valued options. 326 327 --+ Like the -+ command, but takes a long option name rather than a 328 single option letter. 329 330 -! Followed by one of the command line option letters, this will 331 reset the option to the "opposite" of its default setting and 332 print a message describing the new setting. This does not work 333 for numeric or string-valued options. 334 335 --! Like the -! command, but takes a long option name rather than a 336 single option letter. 337 338 _ (Underscore.) Followed by one of the command line option let- 339 ters, this will print a message describing the current setting 340 of that option. The setting of the option is not changed. 341 342 __ (Double underscore.) Like the _ (underscore) command, but takes 343 a long option name rather than a single option letter. You must 344 press RETURN after typing the option name. 345 346 +cmd Causes the specified cmd to be executed each time a new file is 347 examined. For example, +G causes _l_e_s_s to initially display each 348 file starting at the end rather than the beginning. 349 350 V Prints the version number of _l_e_s_s being run. 351 352 q or Q or :q or :Q or ZZ 353 Exits _l_e_s_s_. 354 355 The following four commands may or may not be valid, depending on your 356 particular installation. 357 358 359 v Invokes an editor to edit the current file being viewed. The 360 editor is taken from the environment variable VISUAL if defined, 361 or EDITOR if VISUAL is not defined, or defaults to "vi" if nei- 362 ther VISUAL nor EDITOR is defined. See also the discussion of 363 LESSEDIT under the section on PROMPTS below. 364 365 ! shell-command 366 Invokes a shell to run the shell-command given. A percent sign 367 (%) in the command is replaced by the name of the current file. 368 A pound sign (#) is replaced by the name of the previously exam- 369 ined file. "!!" repeats the last shell command. "!" with no 370 shell command simply invokes a shell. On Unix systems, the 371 shell is taken from the environment variable SHELL, or defaults 372 to "sh". On MS-DOS and OS/2 systems, the shell is the normal 373 command processor. 374 375 | <m> shell-command 376 <m> represents any mark letter. Pipes a section of the input 377 file to the given shell command. The section of the file to be 378 piped is between the first line on the current screen and the 379 position marked by the letter. <m> may also be ^ or $ to indi- 380 cate beginning or end of file respectively. If <m> is . or new- 381 line, the current screen is piped. 382 383 s filename 384 Save the input to a file. This only works if the input is a 385 pipe, not an ordinary file. 386 387 388OOPPTTIIOONNSS 389 Command line options are described below. Most options may be changed 390 while _l_e_s_s is running, via the "-" command. 391 392 Most options may be given in one of two forms: either a dash followed 393 by a single letter, or two dashes followed by a long option name. A 394 long option name may be abbreviated as long as the abbreviation is 395 unambiguous. For example, --quit-at-eof may be abbreviated --quit, but 396 not --qui, since both --quit-at-eof and --quiet begin with --qui. Some 397 long option names are in uppercase, such as --QUIT-AT-EOF, as distinct 398 from --quit-at-eof. Such option names need only have their first 399 letter capitalized; the remainder of the name may be in either case. 400 For example, --Quit-at-eof is equivalent to --QUIT-AT-EOF. 401 402 Options are also taken from the environment variable "LESS". For exam- 403 ple, to avoid typing "less -options ..." each time _l_e_s_s is invoked, you 404 might tell _c_s_h_: 405 406 setenv LESS "-options" 407 408 or if you use _s_h_: 409 410 LESS="-options"; export LESS 411 412 On MS-DOS, you don't need the quotes, but you should replace any per- 413 cent signs in the options string by double percent signs. 414 415 The environment variable is parsed before the command line, so command 416 line options override the LESS environment variable. If an option 417 appears in the LESS variable, it can be reset to its default value on 418 the command line by beginning the command line option with "-+". 419 420 For options like -P or -D which take a following string, a dollar sign 421 ($) must be used to signal the end of the string. For example, to set 422 two -D options on MS-DOS, you must have a dollar sign between them, 423 like this: 424 425 LESS="-Dn9.1$-Ds4.1" 426 427 428 -? or --help 429 This option displays a summary of the commands accepted by _l_e_s_s 430 (the same as the h command). (Depending on how your shell 431 interprets the question mark, it may be necessary to quote the 432 question mark, thus: "-\?".) 433 434 -a or --search-skip-screen 435 Causes searches to start after the last line displayed on the 436 screen, thus skipping all lines displayed on the screen. By 437 default, searches start at the second line on the screen (or 438 after the last found line; see the -j option). 439 440 -b_n or --buffers=_n 441 Specifies the amount of buffer space _l_e_s_s will use for each 442 file, in units of kilobytes (1024 bytes). By default 64K of 443 buffer space is used for each file (unless the file is a pipe; 444 see the -B option). The -b option specifies instead that _n 445 kilobytes of buffer space should be used for each file. If _n is 446 -1, buffer space is unlimited; that is, the entire file is read 447 into memory. 448 449 -B or --auto-buffers 450 By default, when data is read from a pipe, buffers are allocated 451 automatically as needed. If a large amount of data is read from 452 the pipe, this can cause a large amount of memory to be allo- 453 cated. The -B option disables this automatic allocation of 454 buffers for pipes, so that only 64K (or the amount of space 455 specified by the -b option) is used for the pipe. Warning: use 456 of -B can result in erroneous display, since only the most 457 recently viewed part of the file is kept in memory; any earlier 458 data is lost. 459 460 -c or --clear-screen 461 Causes full screen repaints to be painted from the top line 462 down. By default, full screen repaints are done by scrolling 463 from the bottom of the screen. 464 465 -C or --CLEAR-SCREEN 466 The -C option is like -c, but the screen is cleared before it is 467 repainted. 468 469 -d or --dumb 470 The -d option suppresses the error message normally displayed if 471 the terminal is dumb; that is, lacks some important capability, 472 such as the ability to clear the screen or scroll backward. The 473 -d option does not otherwise change the behavior of _l_e_s_s on a 474 dumb terminal. 475 476 -Dxx_c_o_l_o_r or --color=xx_c_o_l_o_r 477 [MS-DOS only] Sets the color of the text displayed. xx is a sin- 478 gle character which selects the type of text whose color is 479 being set: n=normal, s=standout, d=bold, u=underlined, k=blink. 480 _c_o_l_o_r is a pair of numbers separated by a period. The first 481 number selects the foreground color and the second selects the 482 background color of the text. A single number _N is the same as 483 _N_._0. 484 485 -e or --quit-at-eof 486 Causes _l_e_s_s to automatically exit the second time it reaches 487 end-of-file. By default, the only way to exit _l_e_s_s is via the 488 "q" command. 489 490 -E or --QUIT-AT-EOF 491 Causes _l_e_s_s to automatically exit the first time it reaches end- 492 of-file. 493 494 -f or --force 495 Forces non-regular files to be opened. (A non-regular file is a 496 directory or a device special file.) Also suppresses the warn- 497 ing message when a binary file is opened. By default, _l_e_s_s will 498 refuse to open non-regular files. 499 500 -F or --quit-if-one-screen 501 Causes _l_e_s_s to automatically exit if the entire file can be dis- 502 played on the first screen. 503 504 -g or --hilite-search 505 Normally, _l_e_s_s will highlight ALL strings which match the last 506 search command. The -g option changes this behavior to high- 507 light only the particular string which was found by the last 508 search command. This can cause _l_e_s_s to run somewhat faster than 509 the default. 510 511 -G or --HILITE-SEARCH 512 The -G option suppresses all highlighting of strings found by 513 search commands. 514 515 -h_n or --max-back-scroll=_n 516 Specifies a maximum number of lines to scroll backward. If it 517 is necessary to scroll backward more than _n lines, the screen is 518 repainted in a forward direction instead. (If the terminal does 519 not have the ability to scroll backward, -h0 is implied.) 520 521 -i or --ignore-case 522 Causes searches to ignore case; that is, uppercase and lowercase 523 are considered identical. This option is ignored if any upper- 524 case letters appear in the search pattern; in other words, if a 525 pattern contains uppercase letters, then that search does not 526 ignore case. 527 528 -I or --IGNORE-CASE 529 Like -i, but searches ignore case even if the pattern contains 530 uppercase letters. 531 532 -j_n or --jump-target=_n 533 Specifies a line on the screen where the "target" line is to be 534 positioned. A target line is the object of a text search, tag 535 search, jump to a line number, jump to a file percentage, or 536 jump to a marked position. The screen line is specified by a 537 number: the top line on the screen is 1, the next is 2, and so 538 on. The number may be negative to specify a line relative to 539 the bottom of the screen: the bottom line on the screen is -1, 540 the second to the bottom is -2, and so on. If the -j option is 541 used, searches begin at the line immediately after the target 542 line. For example, if "-j4" is used, the target line is the 543 fourth line on the screen, so searches begin at the fifth line 544 on the screen. 545 546 -J or --status-column 547 Displays a status column at the left edge of the screen. The 548 status column shows the lines that matched the current search. 549 The status column is also used if the -w or -W option is in 550 effect. 551 552 -k_f_i_l_e_n_a_m_e or --lesskey-file=_f_i_l_e_n_a_m_e 553 Causes _l_e_s_s to open and interpret the named file as a _l_e_s_s_k_e_y 554 (1) file. Multiple -k options may be specified. If the LESSKEY 555 or LESSKEY_SYSTEM environment variable is set, or if a lesskey 556 file is found in a standard place (see KEY BINDINGS), it is also 557 used as a _l_e_s_s_k_e_y file. 558 559 -K or --quit-on-intr 560 Causes _l_e_s_s to exit immediately when an interrupt character 561 (usually ^C) is typed. Normally, an interrupt character causes 562 _l_e_s_s to stop whatever it is doing and return to its command 563 prompt. 564 565 -L or --no-lessopen 566 Ignore the LESSOPEN environment variable (see the INPUT PREPRO- 567 CESSOR section below). This option can be set from within _l_e_s_s, 568 but it will apply only to files opened subsequently, not to the 569 file which is currently open. 570 571 -m or --long-prompt 572 Causes _l_e_s_s to prompt verbosely (like _m_o_r_e), with the percent 573 into the file. By default, _l_e_s_s prompts with a colon. 574 575 -M or --LONG-PROMPT 576 Causes _l_e_s_s to prompt even more verbosely than _m_o_r_e_. 577 578 -n or --line-numbers 579 Suppresses line numbers. The default (to use line numbers) may 580 cause _l_e_s_s to run more slowly in some cases, especially with a 581 very large input file. Suppressing line numbers with the -n 582 option will avoid this problem. Using line numbers means: the 583 line number will be displayed in the verbose prompt and in the = 584 command, and the v command will pass the current line number to 585 the editor (see also the discussion of LESSEDIT in PROMPTS 586 below). 587 588 -N or --LINE-NUMBERS 589 Causes a line number to be displayed at the beginning of each 590 line in the display. 591 592 -o_f_i_l_e_n_a_m_e or --log-file=_f_i_l_e_n_a_m_e 593 Causes _l_e_s_s to copy its input to the named file as it is being 594 viewed. This applies only when the input file is a pipe, not an 595 ordinary file. If the file already exists, _l_e_s_s will ask for 596 confirmation before overwriting it. 597 598 -O_f_i_l_e_n_a_m_e or --LOG-FILE=_f_i_l_e_n_a_m_e 599 The -O option is like -o, but it will overwrite an existing file 600 without asking for confirmation. 601 602 If no log file has been specified, the -o and -O options can be 603 used from within _l_e_s_s to specify a log file. Without a file 604 name, they will simply report the name of the log file. The "s" 605 command is equivalent to specifying -o from within _l_e_s_s_. 606 607 -p_p_a_t_t_e_r_n or --pattern=_p_a_t_t_e_r_n 608 The -p option on the command line is equivalent to specifying 609 +/_p_a_t_t_e_r_n; that is, it tells _l_e_s_s to start at the first occur- 610 rence of _p_a_t_t_e_r_n in the file. 611 612 -P_p_r_o_m_p_t or --prompt=_p_r_o_m_p_t 613 Provides a way to tailor the three prompt styles to your own 614 preference. This option would normally be put in the LESS envi- 615 ronment variable, rather than being typed in with each _l_e_s_s com- 616 mand. Such an option must either be the last option in the LESS 617 variable, or be terminated by a dollar sign. -Ps followed by a 618 string changes the default (short) prompt to that string. -Pm 619 changes the medium (-m) prompt. -PM changes the long (-M) 620 prompt. -Ph changes the prompt for the help screen. -P= 621 changes the message printed by the = command. -Pw changes the 622 message printed while waiting for data (in the F command). All 623 prompt strings consist of a sequence of letters and special 624 escape sequences. See the section on PROMPTS for more details. 625 626 -q or --quiet or --silent 627 Causes moderately "quiet" operation: the terminal bell is not 628 rung if an attempt is made to scroll past the end of the file or 629 before the beginning of the file. If the terminal has a "visual 630 bell", it is used instead. The bell will be rung on certain 631 other errors, such as typing an invalid character. The default 632 is to ring the terminal bell in all such cases. 633 634 -Q or --QUIET or --SILENT 635 Causes totally "quiet" operation: the terminal bell is never 636 rung. 637 638 -r or --raw-control-chars 639 Causes "raw" control characters to be displayed. The default is 640 to display control characters using the caret notation; for 641 example, a control-A (octal 001) is displayed as "^A". Warning: 642 when the -r option is used, _l_e_s_s cannot keep track of the actual 643 appearance of the screen (since this depends on how the screen 644 responds to each type of control character). Thus, various dis- 645 play problems may result, such as long lines being split in the 646 wrong place. 647 648 -R or --RAW-CONTROL-CHARS 649 Like -r, but only ANSI "color" escape sequences are output in 650 "raw" form. Unlike -r, the screen appearance is maintained cor- 651 rectly in most cases. ANSI "color" escape sequences are 652 sequences of the form: 653 654 ESC [ ... m 655 656 where the "..." is zero or more color specification characters 657 For the purpose of keeping track of screen appearance, ANSI 658 color escape sequences are assumed to not move the cursor. You 659 can make _l_e_s_s think that characters other than "m" can end ANSI 660 color escape sequences by setting the environment variable 661 LESSANSIENDCHARS to the list of characters which can end a color 662 escape sequence. And you can make _l_e_s_s think that characters 663 other than the standard ones may appear between the ESC and the 664 m by setting the environment variable LESSANSIMIDCHARS to the 665 list of characters which can appear. 666 667 -s or --squeeze-blank-lines 668 Causes consecutive blank lines to be squeezed into a single 669 blank line. This is useful when viewing _n_r_o_f_f output. 670 671 -S or --chop-long-lines 672 Causes lines longer than the screen width to be chopped rather 673 than folded. That is, the portion of a long line that does not 674 fit in the screen width is not shown. The default is to fold 675 long lines; that is, display the remainder on the next line. 676 677 -t_t_a_g or --tag=_t_a_g 678 The -t option, followed immediately by a TAG, will edit the file 679 containing that tag. For this to work, tag information must be 680 available; for example, there may be a file in the current 681 directory called "tags", which was previously built by _c_t_a_g_s (1) 682 or an equivalent command. If the environment variable LESSGLOB- 683 ALTAGS is set, it is taken to be the name of a command compati- 684 ble with _g_l_o_b_a_l (1), and that command is executed to find the 685 tag. (See http://www.gnu.org/software/global/global.html). The 686 -t option may also be specified from within _l_e_s_s (using the - 687 command) as a way of examining a new file. The command ":t" is 688 equivalent to specifying -t from within _l_e_s_s_. 689 690 -T_t_a_g_s_f_i_l_e or --tag-file=_t_a_g_s_f_i_l_e 691 Specifies a tags file to be used instead of "tags". 692 693 -u or --underline-special 694 Causes backspaces and carriage returns to be treated as print- 695 able characters; that is, they are sent to the terminal when 696 they appear in the input. 697 698 -U or --UNDERLINE-SPECIAL 699 Causes backspaces, tabs and carriage returns to be treated as 700 control characters; that is, they are handled as specified by 701 the -r option. 702 703 By default, if neither -u nor -U is given, backspaces which 704 appear adjacent to an underscore character are treated spe- 705 cially: the underlined text is displayed using the terminal's 706 hardware underlining capability. Also, backspaces which appear 707 between two identical characters are treated specially: the 708 overstruck text is printed using the terminal's hardware bold- 709 face capability. Other backspaces are deleted, along with the 710 preceding character. Carriage returns immediately followed by a 711 newline are deleted. other carriage returns are handled as 712 specified by the -r option. Text which is overstruck or under- 713 lined can be searched for if neither -u nor -U is in effect. 714 715 -V or --version 716 Displays the version number of _l_e_s_s_. 717 718 -w or --hilite-unread 719 Temporarily highlights the first "new" line after a forward 720 movement of a full page. The first "new" line is the line imme- 721 diately following the line previously at the bottom of the 722 screen. Also highlights the target line after a g or p command. 723 The highlight is removed at the next command which causes move- 724 ment. The entire line is highlighted, unless the -J option is 725 in effect, in which case only the status column is highlighted. 726 727 -W or --HILITE-UNREAD 728 Like -w, but temporarily highlights the first new line after any 729 forward movement command larger than one line. 730 731 -x_n,... or --tabs=_n,... 732 Sets tab stops. If only one _n is specified, tab stops are set 733 at multiples of _n. If multiple values separated by commas are 734 specified, tab stops are set at those positions, and then con- 735 tinue with the same spacing as the last two. For example, 736 _-_x_9_,_1_7 will set tabs at positions 9, 17, 25, 33, etc. The 737 default for _n is 8. 738 739 -X or --no-init 740 Disables sending the termcap initialization and deinitialization 741 strings to the terminal. This is sometimes desirable if the 742 deinitialization string does something unnecessary, like clear- 743 ing the screen. 744 745 --no-keypad 746 Disables sending the keypad initialization and deinitialization 747 strings to the terminal. This is sometimes useful if the keypad 748 strings make the numeric keypad behave in an undesirable manner. 749 750 -y_n or --max-forw-scroll=_n 751 Specifies a maximum number of lines to scroll forward. If it is 752 necessary to scroll forward more than _n lines, the screen is 753 repainted instead. The -c or -C option may be used to repaint 754 from the top of the screen if desired. By default, any forward 755 movement causes scrolling. 756 757 -[z]_n or --window=_n 758 Changes the default scrolling window size to _n lines. The 759 default is one screenful. The z and w commands can also be used 760 to change the window size. The "z" may be omitted for compati- 761 bility with _m_o_r_e_. If the number _n is negative, it indicates _n 762 lines less than the current screen size. For example, if the 763 screen is 24 lines, _-_z_-_4 sets the scrolling window to 20 lines. 764 If the screen is resized to 40 lines, the scrolling window auto- 765 matically changes to 36 lines. 766 767 -_"_c_c or --quotes=_c_c 768 Changes the filename quoting character. This may be necessary 769 if you are trying to name a file which contains both spaces and 770 quote characters. Followed by a single character, this changes 771 the quote character to that character. Filenames containing a 772 space should then be surrounded by that character rather than by 773 double quotes. Followed by two characters, changes the open 774 quote to the first character, and the close quote to the second 775 character. Filenames containing a space should then be preceded 776 by the open quote character and followed by the close quote 777 character. Note that even after the quote characters are 778 changed, this option remains -" (a dash followed by a double 779 quote). 780 781 -~ or --tilde 782 Normally lines after end of file are displayed as a single tilde 783 (~). This option causes lines after end of file to be displayed 784 as blank lines. 785 786 -# or --shift 787 Specifies the default number of positions to scroll horizontally 788 in the RIGHTARROW and LEFTARROW commands. If the number speci- 789 fied is zero, it sets the default number of positions to one 790 half of the screen width. 791 792 -- A command line argument of "--" marks the end of option argu- 793 ments. Any arguments following this are interpreted as file- 794 names. This can be useful when viewing a file whose name begins 795 with a "-" or "+". 796 797 + If a command line option begins with ++, the remainder of that 798 option is taken to be an initial command to _l_e_s_s_. For example, 799 +G tells _l_e_s_s to start at the end of the file rather than the 800 beginning, and +/xyz tells it to start at the first occurrence 801 of "xyz" in the file. As a special case, +<number> acts like 802 +<number>g; that is, it starts the display at the specified line 803 number (however, see the caveat under the "g" command above). 804 If the option starts with ++, the initial command applies to 805 every file being viewed, not just the first one. The + command 806 described previously may also be used to set (or change) an ini- 807 tial command for every file. 808 809 810LLIINNEE EEDDIITTIINNGG 811 When entering command line at the bottom of the screen (for example, a 812 filename for the :e command, or the pattern for a search command), 813 certain keys can be used to manipulate the command line. Most commands 814 have an alternate form in [ brackets ] which can be used if a key does 815 not exist on a particular keyboard. (The bracketed forms do not work 816 in the MS-DOS version.) Any of these special keys may be entered lit- 817 erally by preceding it with the "literal" character, either ^V or ^A. 818 A backslash itself may also be entered literally by entering two back- 819 slashes. 820 821 LEFTARROW [ ESC-h ] 822 Move the cursor one space to the left. 823 824 RIGHTARROW [ ESC-l ] 825 Move the cursor one space to the right. 826 827 ^LEFTARROW [ ESC-b or ESC-LEFTARROW ] 828 (That is, CONTROL and LEFTARROW simultaneously.) Move the cur- 829 sor one word to the left. 830 831 ^RIGHTARROW [ ESC-w or ESC-RIGHTARROW ] 832 (That is, CONTROL and RIGHTARROW simultaneously.) Move the cur- 833 sor one word to the right. 834 835 HOME [ ESC-0 ] 836 Move the cursor to the beginning of the line. 837 838 END [ ESC-$ ] 839 Move the cursor to the end of the line. 840 841 BACKSPACE 842 Delete the character to the left of the cursor, or cancel the 843 command if the command line is empty. 844 845 DELETE or [ ESC-x ] 846 Delete the character under the cursor. 847 848 ^BACKSPACE [ ESC-BACKSPACE ] 849 (That is, CONTROL and BACKSPACE simultaneously.) Delete the 850 word to the left of the cursor. 851 852 ^DELETE [ ESC-X or ESC-DELETE ] 853 (That is, CONTROL and DELETE simultaneously.) Delete the word 854 under the cursor. 855 856 UPARROW [ ESC-k ] 857 Retrieve the previous command line. 858 859 DOWNARROW [ ESC-j ] 860 Retrieve the next command line. 861 862 TAB Complete the partial filename to the left of the cursor. If it 863 matches more than one filename, the first match is entered into 864 the command line. Repeated TABs will cycle thru the other 865 matching filenames. If the completed filename is a directory, a 866 "/" is appended to the filename. (On MS-DOS systems, a "\" is 867 appended.) The environment variable LESSSEPARATOR can be used 868 to specify a different character to append to a directory name. 869 870 BACKTAB [ ESC-TAB ] 871 Like, TAB, but cycles in the reverse direction thru the matching 872 filenames. 873 874 ^L Complete the partial filename to the left of the cursor. If it 875 matches more than one filename, all matches are entered into the 876 command line (if they fit). 877 878 ^U (Unix and OS/2) or ESC (MS-DOS) 879 Delete the entire command line, or cancel the command if the 880 command line is empty. If you have changed your line-kill char- 881 acter in Unix to something other than ^U, that character is used 882 instead of ^U. 883 884 885KKEEYY BBIINNDDIINNGGSS 886 You may define your own _l_e_s_s commands by using the program _l_e_s_s_k_e_y (1) 887 to create a lesskey file. This file specifies a set of command keys 888 and an action associated with each key. You may also use _l_e_s_s_k_e_y to 889 change the line-editing keys (see LINE EDITING), and to set environment 890 variables. If the environment variable LESSKEY is set, _l_e_s_s uses that 891 as the name of the lesskey file. Otherwise, _l_e_s_s looks in a standard 892 place for the lesskey file: On Unix systems, _l_e_s_s looks for a lesskey 893 file called "$HOME/.less". On MS-DOS and Windows systems, _l_e_s_s looks 894 for a lesskey file called "$HOME/_less", and if it is not found there, 895 then looks for a lesskey file called "_less" in any directory specified 896 in the PATH environment variable. On OS/2 systems, _l_e_s_s looks for a 897 lesskey file called "$HOME/less.ini", and if it is not found, then 898 looks for a lesskey file called "less.ini" in any directory specified 899 in the INIT environment variable, and if it not found there, then looks 900 for a lesskey file called "less.ini" in any directory specified in the 901 PATH environment variable. See the _l_e_s_s_k_e_y manual page for more 902 details. 903 904 A system-wide lesskey file may also be set up to provide key bindings. 905 If a key is defined in both a local lesskey file and in the system-wide 906 file, key bindings in the local file take precedence over those in the 907 system-wide file. If the environment variable LESSKEY_SYSTEM is set, 908 _l_e_s_s uses that as the name of the system-wide lesskey file. Otherwise, 909 _l_e_s_s looks in a standard place for the system-wide lesskey file: On 910 Unix systems, the system-wide lesskey file is /usr/local/etc/sysless. 911 (However, if _l_e_s_s was built with a different sysconf directory than 912 /usr/local/etc, that directory is where the sysless file is found.) On 913 MS-DOS and Windows systems, the system-wide lesskey file is c:\_sys- 914 less. On OS/2 systems, the system-wide lesskey file is c:\sysless.ini. 915 916 917IINNPPUUTT PPRREEPPRROOCCEESSSSOORR 918 You may define an "input preprocessor" for _l_e_s_s_. Before _l_e_s_s opens a 919 file, it first gives your input preprocessor a chance to modify the way 920 the contents of the file are displayed. An input preprocessor is sim- 921 ply an executable program (or shell script), which writes the contents 922 of the file to a different file, called the replacement file. The con- 923 tents of the replacement file are then displayed in place of the con- 924 tents of the original file. However, it will appear to the user as if 925 the original file is opened; that is, _l_e_s_s will display the original 926 filename as the name of the current file. 927 928 An input preprocessor receives one command line argument, the original 929 filename, as entered by the user. It should create the replacement 930 file, and when finished, print the name of the replacement file to its 931 standard output. If the input preprocessor does not output a replace- 932 ment filename, _l_e_s_s uses the original file, as normal. The input pre- 933 processor is not called when viewing standard input. To set up an 934 input preprocessor, set the LESSOPEN environment variable to a command 935 line which will invoke your input preprocessor. This command line 936 should include one occurrence of the string "%s", which will be 937 replaced by the filename when the input preprocessor command is 938 invoked. 939 940 When _l_e_s_s closes a file opened in such a way, it will call another pro- 941 gram, called the input postprocessor, which may perform any desired 942 clean-up action (such as deleting the replacement file created by 943 LESSOPEN). This program receives two command line arguments, the orig- 944 inal filename as entered by the user, and the name of the replacement 945 file. To set up an input postprocessor, set the LESSCLOSE environment 946 variable to a command line which will invoke your input postprocessor. 947 It may include two occurrences of the string "%s"; the first is 948 replaced with the original name of the file and the second with the 949 name of the replacement file, which was output by LESSOPEN. 950 951 For example, on many Unix systems, these two scripts will allow you to 952 keep files in compressed format, but still let _l_e_s_s view them directly: 953 954 lessopen.sh: 955 #! /bin/sh 956 case "$1" in 957 *.Z) uncompress - 958 if [ -s /tmp/less.$$ ]; then 959 echo /tmp/less.$$ 960 else 961 rm -f /tmp/less.$$ 962 fi 963 ;; 964 esac 965 966 lessclose.sh: 967 #! /bin/sh 968 rm $2 969 970 To use these scripts, put them both where they can be executed and set 971 LESSOPEN="lessopen.sh %s", and LESSCLOSE="lessclose.sh %s %s". More 972 complex LESSOPEN and LESSCLOSE scripts may be written to accept other 973 types of compressed files, and so on. 974 975 It is also possible to set up an input preprocessor to pipe the file 976 data directly to _l_e_s_s_, rather than putting the data into a replacement 977 file. This avoids the need to decompress the entire file before start- 978 ing to view it. An input preprocessor that works this way is called an 979 input pipe. An input pipe, instead of writing the name of a replace- 980 ment file on its standard output, writes the entire contents of the 981 replacement file on its standard output. If the input pipe does not 982 write any characters on its standard output, then there is no replace- 983 ment file and _l_e_s_s uses the original file, as normal. To use an input 984 pipe, make the first character in the LESSOPEN environment variable a 985 vertical bar (|) to signify that the input preprocessor is an input 986 pipe. 987 988 For example, on many Unix systems, this script will work like the pre- 989 vious example scripts: 990 991 lesspipe.sh: 992 #! /bin/sh 993 case "$1" in 994 *.Z) uncompress -c $1 2>/dev/null 995 ;; 996 esac 997 998 To use this script, put it where it can be executed and set 999 LESSOPEN="|lesspipe.sh %s". When an input pipe is used, a LESSCLOSE 1000 postprocessor can be used, but it is usually not necessary since there 1001 is no replacement file to clean up. In this case, the replacement file 1002 name passed to the LESSCLOSE postprocessor is "-". 1003 1004 1005NNAATTIIOONNAALL CCHHAARRAACCTTEERR SSEETTSS 1006 There are three types of characters in the input file: 1007 1008 normal characters 1009 can be displayed directly to the screen. 1010 1011 control characters 1012 should not be displayed directly, but are expected to be found 1013 in ordinary text files (such as backspace and tab). 1014 1015 binary characters 1016 should not be displayed directly and are not expected to be 1017 found in text files. 1018 1019 A "character set" is simply a description of which characters are to be 1020 considered normal, control, and binary. The LESSCHARSET environment 1021 variable may be used to select a character set. Possible values for 1022 LESSCHARSET are: 1023 1024 ascii BS, TAB, NL, CR, and formfeed are control characters, all chars 1025 with values between 32 and 126 are normal, and all others are 1026 binary. 1027 1028 iso8859 1029 Selects an ISO 8859 character set. This is the same as ASCII, 1030 except characters between 160 and 255 are treated as normal 1031 characters. 1032 1033 latin1 Same as iso8859. 1034 1035 latin9 Same as iso8859. 1036 1037 dos Selects a character set appropriate for MS-DOS. 1038 1039 ebcdic Selects an EBCDIC character set. 1040 1041 IBM-1047 1042 Selects an EBCDIC character set used by OS/390 Unix Services. 1043 This is the EBCDIC analogue of latin1. You get similar results 1044 by setting either LESSCHARSET=IBM-1047 or LC_CTYPE=en_US in your 1045 environment. 1046 1047 koi8-r Selects a Russian character set. 1048 1049 next Selects a character set appropriate for NeXT computers. 1050 1051 utf-8 Selects the UTF-8 encoding of the ISO 10646 character set. 1052 1053 windows 1054 Selects a character set appropriate for Microsoft Windows (cp 1055 1251). 1056 1057 In special cases, it may be desired to tailor _l_e_s_s to use a character 1058 set other than the ones definable by LESSCHARSET. In this case, the 1059 environment variable LESSCHARDEF can be used to define a character set. 1060 It should be set to a string where each character in the string repre- 1061 sents one character in the character set. The character "." is used 1062 for a normal character, "c" for control, and "b" for binary. A decimal 1063 number may be used for repetition. For example, "bccc4b." would mean 1064 character 0 is binary, 1, 2 and 3 are control, 4, 5, 6 and 7 are 1065 binary, and 8 is normal. All characters after the last are taken to be 1066 the same as the last, so characters 9 through 255 would be normal. 1067 (This is an example, and does not necessarily represent any real char- 1068 acter set.) 1069 1070 This table shows the value of LESSCHARDEF which is equivalent to each 1071 of the possible values for LESSCHARSET: 1072 1073 ascii 8bcccbcc18b95.b 1074 dos 8bcccbcc12bc5b95.b. 1075 ebcdic 5bc6bcc7bcc41b.9b7.9b5.b..8b6.10b6.b9.7b 1076 9.8b8.17b3.3b9.7b9.8b8.6b10.b.b.b. 1077 IBM-1047 4cbcbc3b9cbccbccbb4c6bcc5b3cbbc4bc4bccbc 1078 191.b 1079 iso8859 8bcccbcc18b95.33b. 1080 koi8-r 8bcccbcc18b95.b128. 1081 latin1 8bcccbcc18b95.33b. 1082 next 8bcccbcc18b95.bb125.bb 1083 1084 If neither LESSCHARSET nor LESSCHARDEF is set, but any of the strings 1085 "UTF-8", "UTF8", "utf-8" or "utf8" is found in the LC_ALL, LC_TYPE or 1086 LANG environment variables, then the default character set is utf-8. 1087 1088 If that string is not found, but your system supports the _s_e_t_l_o_c_a_l_e 1089 interface, _l_e_s_s will use setlocale to determine the character set. 1090 setlocale is controlled by setting the LANG or LC_CTYPE environment 1091 variables. 1092 1093 Finally, if the _s_e_t_l_o_c_a_l_e interface is also not available, the default 1094 character set is latin1. 1095 1096 Control and binary characters are displayed in standout (reverse 1097 video). Each such character is displayed in caret notation if possible 1098 (e.g. ^A for control-A). Caret notation is used only if inverting the 1099 0100 bit results in a normal printable character. Otherwise, the char- 1100 acter is displayed as a hex number in angle brackets. This format can 1101 be changed by setting the LESSBINFMT environment variable. LESSBINFMT 1102 may begin with a "*" and one character to select the display attribute: 1103 "*k" is blinking, "*d" is bold, "*u" is underlined, "*s" is standout, 1104 and "*n" is normal. If LESSBINFMT does not begin with a "*", normal 1105 attribute is assumed. The remainder of LESSBINFMT is a string which 1106 may include one printf-style escape sequence (a % followed by x, X, o, 1107 d, etc.). For example, if LESSBINFMT is "*u[%x]", binary characters 1108 are displayed in underlined hexadecimal surrounded by brackets. The 1109 default if no LESSBINFMT is specified is "*s<%X>". The default if no 1110 LESSBINFMT is specified is "*s<%02X>". Warning: the result of expand- 1111 ing the character via LESSBINFMT must be less than 31 characters. 1112 1113 When the character set is utf-8, the LESSUTFBINFMT environment variable 1114 acts similarly to LESSBINFMT but it applies to Unicode code points that 1115 were successfully decoded but are unsuitable for display (e.g., unas- 1116 signed code points). Its default value is "<U+%04lX>". Note that 1117 LESSUTFBINFMT and LESSBINFMT share their display attribute setting 1118 ("*x") so specifying one will affect both; LESSUTFBINFMT is read after 1119 LESSBINFMT so its setting, if any, will have priority. Problematic 1120 octets in a UTF-8 file (octets of a truncated sequence, octets of a 1121 complete but non-shortest form sequence, illegal octets, and stray 1122 trailing octets) are displayed individually using LESSBINFMT so as to 1123 facilitate diagnostic of how the UTF-8 file is ill-formed. 1124 1125 1126PPRROOMMPPTTSS 1127 The -P option allows you to tailor the prompt to your preference. The 1128 string given to the -P option replaces the specified prompt string. 1129 Certain characters in the string are interpreted specially. The prompt 1130 mechanism is rather complicated to provide flexibility, but the ordi- 1131 nary user need not understand the details of constructing personalized 1132 prompt strings. 1133 1134 A percent sign followed by a single character is expanded according to 1135 what the following character is: 1136 1137 %b_X Replaced by the byte offset into the current input file. The b 1138 is followed by a single character (shown as _X above) which spec- 1139 ifies the line whose byte offset is to be used. If the charac- 1140 ter is a "t", the byte offset of the top line in the display is 1141 used, an "m" means use the middle line, a "b" means use the bot- 1142 tom line, a "B" means use the line just after the bottom line, 1143 and a "j" means use the "target" line, as specified by the -j 1144 option. 1145 1146 %B Replaced by the size of the current input file. 1147 1148 %c Replaced by the column number of the text appearing in the first 1149 column of the screen. 1150 1151 %d_X Replaced by the page number of a line in the input file. The 1152 line to be used is determined by the _X, as with the %b option. 1153 1154 %D Replaced by the number of pages in the input file, or equiva- 1155 lently, the page number of the last line in the input file. 1156 1157 %E Replaced by the name of the editor (from the VISUAL environment 1158 variable, or the EDITOR environment variable if VISUAL is not 1159 defined). See the discussion of the LESSEDIT feature below. 1160 1161 %f Replaced by the name of the current input file. 1162 1163 %i Replaced by the index of the current file in the list of input 1164 files. 1165 1166 %l_X Replaced by the line number of a line in the input file. The 1167 line to be used is determined by the _X, as with the %b option. 1168 1169 %L Replaced by the line number of the last line in the input file. 1170 1171 %m Replaced by the total number of input files. 1172 1173 %p_X Replaced by the percent into the current input file, based on 1174 byte offsets. The line used is determined by the _X as with the 1175 %b option. 1176 1177 %P_X Replaced by the percent into the current input file, based on 1178 line numbers. The line used is determined by the _X as with the 1179 %b option. 1180 1181 %s Same as %B. 1182 1183 %t Causes any trailing spaces to be removed. Usually used at the 1184 end of the string, but may appear anywhere. 1185 1186 %x Replaced by the name of the next input file in the list. 1187 1188 If any item is unknown (for example, the file size if input is a pipe), 1189 a question mark is printed instead. 1190 1191 The format of the prompt string can be changed depending on certain 1192 conditions. A question mark followed by a single character acts like 1193 an "IF": depending on the following character, a condition is evalu- 1194 ated. If the condition is true, any characters following the question 1195 mark and condition character, up to a period, are included in the 1196 prompt. If the condition is false, such characters are not included. 1197 A colon appearing between the question mark and the period can be used 1198 to establish an "ELSE": any characters between the colon and the period 1199 are included in the string if and only if the IF condition is false. 1200 Condition characters (which follow a question mark) may be: 1201 1202 ?a True if any characters have been included in the prompt so far. 1203 1204 ?b_X True if the byte offset of the specified line is known. 1205 1206 ?B True if the size of current input file is known. 1207 1208 ?c True if the text is horizontally shifted (%c is not zero). 1209 1210 ?d_X True if the page number of the specified line is known. 1211 1212 ?e True if at end-of-file. 1213 1214 ?f True if there is an input filename (that is, if input is not a 1215 pipe). 1216 1217 ?l_X True if the line number of the specified line is known. 1218 1219 ?L True if the line number of the last line in the file is known. 1220 1221 ?m True if there is more than one input file. 1222 1223 ?n True if this is the first prompt in a new input file. 1224 1225 ?p_X True if the percent into the current input file, based on byte 1226 offsets, of the specified line is known. 1227 1228 ?P_X True if the percent into the current input file, based on line 1229 numbers, of the specified line is known. 1230 1231 ?s Same as "?B". 1232 1233 ?x True if there is a next input file (that is, if the current 1234 input file is not the last one). 1235 1236 Any characters other than the special ones (question mark, colon, 1237 period, percent, and backslash) become literally part of the prompt. 1238 Any of the special characters may be included in the prompt literally 1239 by preceding it with a backslash. 1240 1241 Some examples: 1242 1243 ?f%f:Standard input. 1244 1245 This prompt prints the filename, if known; otherwise the string "Stan- 1246 dard input". 1247 1248 ?f%f .?ltLine %lt:?pt%pt\%:?btByte %bt:-... 1249 1250 This prompt would print the filename, if known. The filename is fol- 1251 lowed by the line number, if known, otherwise the percent if known, 1252 otherwise the byte offset if known. Otherwise, a dash is printed. 1253 Notice how each question mark has a matching period, and how the % 1254 after the %pt is included literally by escaping it with a backslash. 1255 1256 ?n?f%f .?m(file %i of %m) ..?e(END) ?x- Next\: %x..%t 1257 1258 This prints the filename if this is the first prompt in a file, fol- 1259 lowed by the "file N of N" message if there is more than one input 1260 file. Then, if we are at end-of-file, the string "(END)" is printed 1261 followed by the name of the next file, if there is one. Finally, any 1262 trailing spaces are truncated. This is the default prompt. For refer- 1263 ence, here are the defaults for the other two prompts (-m and -M 1264 respectively). Each is broken into two lines here for readability 1265 only. 1266 1267 ?n?f%f .?m(file %i of %m) ..?e(END) ?x- Next\: %x.: 1268 ?pB%pB\%:byte %bB?s/%s...%t 1269 1270 ?f%f .?n?m(file %i of %m) ..?ltlines %lt-%lb?L/%L. : 1271 byte %bB?s/%s. .?e(END) ?x- Next\: %x.:?pB%pB\%..%t 1272 1273 And here is the default message produced by the = command: 1274 1275 ?f%f .?m(file %i of %m) .?ltlines %lt-%lb?L/%L. . 1276 byte %bB?s/%s. ?e(END) :?pB%pB\%..%t 1277 1278 The prompt expansion features are also used for another purpose: if an 1279 environment variable LESSEDIT is defined, it is used as the command to 1280 be executed when the v command is invoked. The LESSEDIT string is 1281 expanded in the same way as the prompt strings. The default value for 1282 LESSEDIT is: 1283 1284 %E ?lm+%lm. %f 1285 1286 Note that this expands to the editor name, followed by a + and the line 1287 number, followed by the file name. If your editor does not accept the 1288 "+linenumber" syntax, or has other differences in invocation syntax, 1289 the LESSEDIT variable can be changed to modify this default. 1290 1291 1292SSEECCUURRIITTYY 1293 When the environment variable LESSSECURE is set to 1, _l_e_s_s runs in a 1294 "secure" mode. This means these features are disabled: 1295 1296 ! the shell command 1297 1298 | the pipe command 1299 1300 :e the examine command. 1301 1302 v the editing command 1303 1304 s -o log files 1305 1306 -k use of lesskey files 1307 1308 -t use of tags files 1309 1310 metacharacters in filenames, such as * 1311 1312 filename completion (TAB, ^L) 1313 1314 Less can also be compiled to be permanently in "secure" mode. 1315 1316 1317EENNVVIIRROONNMMEENNTT VVAARRIIAABBLLEESS 1318 Environment variables may be specified either in the system environment 1319 as usual, or in a _l_e_s_s_k_e_y (1) file. If environment variables are 1320 defined in more than one place, variables defined in a local lesskey 1321 file take precedence over variables defined in the system environment, 1322 which take precedence over variables defined in the system-wide lesskey 1323 file. 1324 1325 COLUMNS 1326 Sets the number of columns on the screen. Takes precedence over 1327 the number of columns specified by the TERM variable. (But if 1328 you have a windowing system which supports TIOCGWINSZ or 1329 WIOCGETD, the window system's idea of the screen size takes 1330 precedence over the LINES and COLUMNS environment variables.) 1331 1332 EDITOR The name of the editor (used for the v command). 1333 1334 HOME Name of the user's home directory (used to find a lesskey file 1335 on Unix and OS/2 systems). 1336 1337 HOMEDRIVE, HOMEPATH 1338 Concatenation of the HOMEDRIVE and HOMEPATH environment vari- 1339 ables is the name of the user's home directory if the HOME vari- 1340 able is not set (only in the Windows version). 1341 1342 INIT Name of the user's init directory (used to find a lesskey file 1343 on OS/2 systems). 1344 1345 LANG Language for determining the character set. 1346 1347 LC_CTYPE 1348 Language for determining the character set. 1349 1350 LESS Options which are passed to _l_e_s_s automatically. 1351 1352 LESSANSIENDCHARS 1353 Characters which may end an ANSI color escape sequence (default 1354 "m"). 1355 1356 LESSANSIMIDCHARS 1357 Characters which may appear between the ESC character and the 1358 end character in an ANSI color escape sequence (default 1359 "0123456789;[?!"'#%()*+ ". 1360 1361 LESSBINFMT 1362 Format for displaying non-printable, non-control characters. 1363 1364 LESSCHARDEF 1365 Defines a character set. 1366 1367 LESSCHARSET 1368 Selects a predefined character set. 1369 1370 LESSCLOSE 1371 Command line to invoke the (optional) input-postprocessor. 1372 1373 LESSECHO 1374 Name of the lessecho program (default "lessecho"). The lessecho 1375 program is needed to expand metacharacters, such as * and ?, in 1376 filenames on Unix systems. 1377 1378 LESSEDIT 1379 Editor prototype string (used for the v command). See discus- 1380 sion under PROMPTS. 1381 1382 LESSGLOBALTAGS 1383 Name of the command used by the -t option to find global tags. 1384 Normally should be set to "global" if your system has the _g_l_o_b_a_l 1385 (1) command. If not set, global tags are not used. 1386 1387 LESSHISTFILE 1388 Name of the history file used to remember search commands and 1389 shell commands between invocations of _l_e_s_s_. If set to "-", a 1390 history file is not used. The default is "$HOME/.lesshst" on 1391 Unix systems, "$HOME/_lesshst" on DOS and Windows systems, or 1392 "$HOME/lesshst.ini" or "$INIT/lesshst.ini" on OS/2 systems. 1393 1394 LESSHISTSIZE 1395 The maximum number of commands to save in the history file. The 1396 default is 100. 1397 1398 LESSKEY 1399 Name of the default lesskey(1) file. 1400 1401 LESSKEY_SYSTEM 1402 Name of the default system-wide lesskey(1) file. 1403 1404 LESSMETACHARS 1405 List of characters which are considered "metacharacters" by the 1406 shell. 1407 1408 LESSMETAESCAPE 1409 Prefix which less will add before each metacharacter in a com- 1410 mand sent to the shell. If LESSMETAESCAPE is an empty string, 1411 commands containing metacharacters will not be passed to the 1412 shell. 1413 1414 LESSOPEN 1415 Command line to invoke the (optional) input-preprocessor. 1416 1417 LESSSECURE 1418 Runs less in "secure" mode. See discussion under SECURITY. 1419 1420 LESSSEPARATOR 1421 String to be appended to a directory name in filename comple- 1422 tion. 1423 1424 LESSUTFBINFMT 1425 Format for displaying non-printable Unicode code points. 1426 1427 LINES Sets the number of lines on the screen. Takes precedence over 1428 the number of lines specified by the TERM variable. (But if you 1429 have a windowing system which supports TIOCGWINSZ or WIOCGETD, 1430 the window system's idea of the screen size takes precedence 1431 over the LINES and COLUMNS environment variables.) 1432 1433 PATH User's search path (used to find a lesskey file on MS-DOS and 1434 OS/2 systems). 1435 1436 SHELL The shell used to execute the ! command, as well as to expand 1437 filenames. 1438 1439 TERM The type of terminal on which _l_e_s_s is being run. 1440 1441 VISUAL The name of the editor (used for the v command). 1442 1443 1444SSEEEE AALLSSOO 1445 lesskey(1) 1446 1447 1448WWAARRNNIINNGGSS 1449 The = command and prompts (unless changed by -P) report the line num- 1450 bers of the lines at the top and bottom of the screen, but the byte and 1451 percent of the line after the one at the bottom of the screen. 1452 1453 If the :e command is used to name more than one file, and one of the 1454 named files has been viewed previously, the new files may be entered 1455 into the list in an unexpected order. 1456 1457 On certain older terminals (the so-called "magic cookie" terminals), 1458 search highlighting will cause an erroneous display. On such termi- 1459 nals, search highlighting is disabled by default to avoid possible 1460 problems. 1461 1462 In certain cases, when search highlighting is enabled and a search pat- 1463 tern begins with a ^, more text than the matching string may be high- 1464 lighted. (This problem does not occur when less is compiled to use the 1465 POSIX regular expression package.) 1466 1467 When viewing text containing ANSI color escape sequences using the -R 1468 option, searching will not find text containing an embedded escape 1469 sequence. Also, search highlighting may change the color of some of 1470 the text which follows the highlighted text. 1471 1472 On some systems, _s_e_t_l_o_c_a_l_e claims that ASCII characters 0 thru 31 are 1473 control characters rather than binary characters. This causes _l_e_s_s to 1474 treat some binary files as ordinary, non-binary files. To workaround 1475 this problem, set the environment variable LESSCHARSET to "ascii" (or 1476 whatever character set is appropriate). 1477 1478 This manual is too long. 1479 1480 See http://www.greenwoodsoftware.com/less for the list of known bugs in 1481 all versions of less. 1482 1483 1484CCOOPPYYRRIIGGHHTT 1485 Copyright (C) 1984-2005 Mark Nudelman 1486 1487 less is part of the GNU project and is free software. You can redis- 1488 tribute it and/or modify it under the terms of either (1) the GNU Gen- 1489 eral Public License as published by the Free Software Foundation; or 1490 (2) the Less License. See the file README in the less distribution for 1491 more details regarding redistribution. You should have received a copy 1492 of the GNU General Public License along with the source for less; see 1493 the file COPYING. If not, write to the Free Software Foundation, 59 1494 Temple Place, Suite 330, Boston, MA 02111-1307, USA. You should also 1495 have received a copy of the Less License; see the file LICENSE. 1496 1497 less is distributed in the hope that it will be useful, but WITHOUT ANY 1498 WARRANTY; without even the implied warranty of MERCHANTABILITY or FIT- 1499 NESS FOR A PARTICULAR PURPOSE. See the GNU General Public License for 1500 more details. 1501 1502 1503AAUUTTHHOORR 1504 Mark Nudelman <markn@greenwoodsoftware.com> 1505 Send bug reports or comments to the above address or to bug- 1506 less@gnu.org. 1507 For more information, see the less homepage at http://www.greenwood- 1508 software.com/less. 1509 1510 1511 1512 Version 394: 03 Dec 2005 LESS(1) 1513