less.man revision 195941
1LESS(1) LESS(1) 2 3 4 5[1mNAME[0m 6 less - opposite of more 7 8[1mSYNOPSIS[0m 9 [1mless -?[0m 10 [1mless --help[0m 11 [1mless -V[0m 12 [1mless --version[0m 13 [1mless [-[+]aBcCdeEfFgGiIJKLmMnNqQrRsSuUVwWX~][0m 14 [1m[-b [4m[22mspace[24m[1m] [-h [4m[22mlines[24m[1m] [-j [4m[22mline[24m[1m] [-k [4m[22mkeyfile[24m[1m][0m 15 [1m[-{oO} [4m[22mlogfile[24m[1m] [-p [4m[22mpattern[24m[1m] [-P [4m[22mprompt[24m[1m] [-t [4m[22mtag[24m[1m][0m 16 [1m[-T [4m[22mtagsfile[24m[1m] [-x [4m[22mtab[24m[1m,...] [-y [4m[22mlines[24m[1m] [-[z] [4m[22mlines[24m[1m][0m 17 [1m[-# [4m[22mshift[24m[1m] [+[+][4m[22mcmd[24m[1m] [--] [[4m[22mfilename[24m[1m]...[0m 18 (See the OPTIONS section for alternate option syntax with long option 19 names.) 20 21 22[1mDESCRIPTION[0m 23 [4mLess[24m is a program similar to [4mmore[24m (1), but which allows backward move- 24 ment in the file as well as forward movement. Also, [4mless[24m 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 [4mvi[24m (1). [4mLess[24m 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 [4mmore[24m and [4mvi.[24m 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 37[1mCOMMANDS[0m 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, and may contain a decimal point. 121 122 P Go to the line containing byte offset N in the file. 123 124 { If a left curly bracket appears in the top line displayed on the 125 screen, the { command will go to the matching right curly 126 bracket. The matching right curly bracket is positioned on the 127 bottom line of the screen. If there is more than one left curly 128 bracket on the top line, a number N may be used to specify the 129 N-th bracket on the line. 130 131 } If a right curly bracket appears in the bottom line displayed on 132 the screen, the } command will go to the matching left curly 133 bracket. The matching left curly bracket is positioned on the 134 top line of the screen. If there is more than one right curly 135 bracket on the top line, a number N may be used to specify the 136 N-th bracket on the line. 137 138 ( Like {, but applies to parentheses rather than curly brackets. 139 140 ) Like }, but applies to parentheses rather than curly brackets. 141 142 [ Like {, but applies to square brackets rather than curly brack- 143 ets. 144 145 ] Like }, but applies to square brackets rather than curly brack- 146 ets. 147 148 ESC-^F Followed by two characters, acts like {, but uses the two char- 149 acters as open and close brackets, respectively. For example, 150 "ESC ^F < >" could be used to go forward to the > which matches 151 the < in the top displayed line. 152 153 ESC-^B Followed by two characters, acts like }, but uses the two char- 154 acters as open and close brackets, respectively. For example, 155 "ESC ^B < >" could be used to go backward to the < which matches 156 the > in the bottom displayed line. 157 158 m Followed by any lowercase letter, marks the current position 159 with that letter. 160 161 ' (Single quote.) Followed by any lowercase letter, returns to 162 the position which was previously marked with that letter. Fol- 163 lowed by another single quote, returns to the position at which 164 the last "large" movement command was executed. Followed by a ^ 165 or $, jumps to the beginning or end of the file respectively. 166 Marks are preserved when a new file is examined, so the ' com- 167 mand can be used to switch between input files. 168 169 ^X^X Same as single quote. 170 171 /pattern 172 Search forward in the file for the N-th line containing the pat- 173 tern. N defaults to 1. The pattern is a regular expression, as 174 recognized by the regular expression library supplied by your 175 system. The search starts at the second line displayed (but see 176 the -a and -j options, which change this). 177 178 Certain characters are special if entered at the beginning of 179 the pattern; they modify the type of search rather than become 180 part of the pattern: 181 182 ^N or ! 183 Search for lines which do NOT match the pattern. 184 185 ^E or * 186 Search multiple files. That is, if the search reaches 187 the END of the current file without finding a match, the 188 search continues in the next file in the command line 189 list. 190 191 ^F or @ 192 Begin the search at the first line of the FIRST file in 193 the command line list, regardless of what is currently 194 displayed on the screen or the settings of the -a or -j 195 options. 196 197 ^K Highlight any text which matches the pattern on the cur- 198 rent screen, but don't move to the first match (KEEP cur- 199 rent position). 200 201 ^R Don't interpret regular expression metacharacters; that 202 is, do a simple textual comparison. 203 204 ?pattern 205 Search backward in the file for the N-th line containing the 206 pattern. The search starts at the line immediately before the 207 top line displayed. 208 209 Certain characters are special as in the / command: 210 211 ^N or ! 212 Search for lines which do NOT match the pattern. 213 214 ^E or * 215 Search multiple files. That is, if the search reaches 216 the beginning of the current file without finding a 217 match, the search continues in the previous file in the 218 command line list. 219 220 ^F or @ 221 Begin the search at the last line of the last file in the 222 command line list, regardless of what is currently dis- 223 played on the screen or the settings of the -a or -j 224 options. 225 226 ^K As in forward searches. 227 228 ^R As in forward searches. 229 230 ESC-/pattern 231 Same as "/*". 232 233 ESC-?pattern 234 Same as "?*". 235 236 n Repeat previous search, for N-th line containing the last pat- 237 tern. If the previous search was modified by ^N, the search is 238 made for the N-th line NOT containing the pattern. If the pre- 239 vious search was modified by ^E, the search continues in the 240 next (or previous) file if not satisfied in the current file. 241 If the previous search was modified by ^R, the search is done 242 without using regular expressions. There is no effect if the 243 previous search was modified by ^F or ^K. 244 245 N Repeat previous search, but in the reverse direction. 246 247 ESC-n Repeat previous search, but crossing file boundaries. The 248 effect is as if the previous search were modified by *. 249 250 ESC-N Repeat previous search, but in the reverse direction and cross- 251 ing file boundaries. 252 253 ESC-u Undo search highlighting. Turn off highlighting of strings 254 matching the current search pattern. If highlighting is already 255 off because of a previous ESC-u command, turn highlighting back 256 on. Any search command will also turn highlighting back on. 257 (Highlighting can also be disabled by toggling the -G option; in 258 that case search commands do not turn highlighting back on.) 259 260 &pattern 261 Display only lines which match the pattern; lines which do not 262 match the pattern are not displayed. If pattern is empty (if 263 you type & immediately followed by ENTER), any filtering is 264 turned off, and all lines are displayed. While filtering is in 265 effect, an ampersand is displayed at the beginning of the 266 prompt, as a reminder that some lines in the file may be hidden. 267 268 Certain characters are special as in the / command: 269 270 ^N or ! 271 Display only lines which do NOT match the pattern. 272 273 ^R Don't interpret regular expression metacharacters; that 274 is, do a simple textual comparison. 275 276 :e [filename] 277 Examine a new file. If the filename is missing, the "current" 278 file (see the :n and :p commands below) from the list of files 279 in the command line is re-examined. A percent sign (%) in the 280 filename is replaced by the name of the current file. A pound 281 sign (#) is replaced by the name of the previously examined 282 file. However, two consecutive percent signs are simply 283 replaced with a single percent sign. This allows you to enter a 284 filename that contains a percent sign in the name. Similarly, 285 two consecutive pound signs are replaced with a single pound 286 sign. The filename is inserted into the command line list of 287 files so that it can be seen by subsequent :n and :p commands. 288 If the filename consists of several files, they are all inserted 289 into the list of files and the first one is examined. If the 290 filename contains one or more spaces, the entire filename should 291 be enclosed in double quotes (also see the -" option). 292 293 ^X^V or E 294 Same as :e. Warning: some systems use ^V as a special literal- 295 ization character. On such systems, you may not be able to use 296 ^V. 297 298 :n Examine the next file (from the list of files given in the com- 299 mand line). If a number N is specified, the N-th next file is 300 examined. 301 302 :p Examine the previous file in the command line list. If a number 303 N is specified, the N-th previous file is examined. 304 305 :x Examine the first file in the command line list. If a number N 306 is specified, the N-th file in the list is examined. 307 308 :d Remove the current file from the list of files. 309 310 t Go to the next tag, if there were more than one matches for the 311 current tag. See the -t option for more details about tags. 312 313 T Go to the previous tag, if there were more than one matches for 314 the current tag. 315 316 = or ^G or :f 317 Prints some information about the file being viewed, including 318 its name and the line number and byte offset of the bottom line 319 being displayed. If possible, it also prints the length of the 320 file, the number of lines in the file and the percent of the 321 file above the last displayed line. 322 323 - Followed by one of the command line option letters (see OPTIONS 324 below), this will change the setting of that option and print a 325 message describing the new setting. If a ^P (CONTROL-P) is 326 entered immediately after the dash, the setting of the option is 327 changed but no message is printed. If the option letter has a 328 numeric value (such as -b or -h), or a string value (such as -P 329 or -t), a new value may be entered after the option letter. If 330 no new value is entered, a message describing the current set- 331 ting is printed and nothing is changed. 332 333 -- Like the - command, but takes a long option name (see OPTIONS 334 below) rather than a single option letter. You must press 335 RETURN after typing the option name. A ^P immediately after the 336 second dash suppresses printing of a message describing the new 337 setting, as in the - command. 338 339 -+ Followed by one of the command line option letters this will 340 reset the option to its default setting and print a message 341 describing the new setting. (The "-+[4mX[24m" command does the same 342 thing as "-+[4mX[24m" on the command line.) This does not work for 343 string-valued options. 344 345 --+ Like the -+ command, but takes a long option name rather than a 346 single option letter. 347 348 -! Followed by one of the command line option letters, this will 349 reset the option to the "opposite" of its default setting and 350 print a message describing the new setting. This does not work 351 for numeric or string-valued options. 352 353 --! Like the -! command, but takes a long option name rather than a 354 single option letter. 355 356 _ (Underscore.) Followed by one of the command line option let- 357 ters, this will print a message describing the current setting 358 of that option. The setting of the option is not changed. 359 360 __ (Double underscore.) Like the _ (underscore) command, but takes 361 a long option name rather than a single option letter. You must 362 press RETURN after typing the option name. 363 364 +cmd Causes the specified cmd to be executed each time a new file is 365 examined. For example, +G causes [4mless[24m to initially display each 366 file starting at the end rather than the beginning. 367 368 V Prints the version number of [4mless[24m being run. 369 370 q or Q or :q or :Q or ZZ 371 Exits [4mless.[0m 372 373 The following four commands may or may not be valid, depending on your 374 particular installation. 375 376 377 v Invokes an editor to edit the current file being viewed. The 378 editor is taken from the environment variable VISUAL if defined, 379 or EDITOR if VISUAL is not defined, or defaults to "vi" if nei- 380 ther VISUAL nor EDITOR is defined. See also the discussion of 381 LESSEDIT under the section on PROMPTS below. 382 383 ! shell-command 384 Invokes a shell to run the shell-command given. A percent sign 385 (%) in the command is replaced by the name of the current file. 386 A pound sign (#) is replaced by the name of the previously exam- 387 ined file. "!!" repeats the last shell command. "!" with no 388 shell command simply invokes a shell. On Unix systems, the 389 shell is taken from the environment variable SHELL, or defaults 390 to "sh". On MS-DOS and OS/2 systems, the shell is the normal 391 command processor. 392 393 | <m> shell-command 394 <m> represents any mark letter. Pipes a section of the input 395 file to the given shell command. The section of the file to be 396 piped is between the first line on the current screen and the 397 position marked by the letter. <m> may also be ^ or $ to indi- 398 cate beginning or end of file respectively. If <m> is . or new- 399 line, the current screen is piped. 400 401 s filename 402 Save the input to a file. This only works if the input is a 403 pipe, not an ordinary file. 404 405 406[1mOPTIONS[0m 407 Command line options are described below. Most options may be changed 408 while [4mless[24m is running, via the "-" command. 409 410 Most options may be given in one of two forms: either a dash followed 411 by a single letter, or two dashes followed by a long option name. A 412 long option name may be abbreviated as long as the abbreviation is 413 unambiguous. For example, --quit-at-eof may be abbreviated --quit, but 414 not --qui, since both --quit-at-eof and --quiet begin with --qui. Some 415 long option names are in uppercase, such as --QUIT-AT-EOF, as distinct 416 from --quit-at-eof. Such option names need only have their first let- 417 ter capitalized; the remainder of the name may be in either case. For 418 example, --Quit-at-eof is equivalent to --QUIT-AT-EOF. 419 420 Options are also taken from the environment variable "LESS". For exam- 421 ple, to avoid typing "less -options ..." each time [4mless[24m is invoked, you 422 might tell [4mcsh:[0m 423 424 setenv LESS "-options" 425 426 or if you use [4msh:[0m 427 428 LESS="-options"; export LESS 429 430 On MS-DOS, you don't need the quotes, but you should replace any per- 431 cent signs in the options string by double percent signs. 432 433 The environment variable is parsed before the command line, so command 434 line options override the LESS environment variable. If an option 435 appears in the LESS variable, it can be reset to its default value on 436 the command line by beginning the command line option with "-+". 437 438 For options like -P or -D which take a following string, a dollar sign 439 ($) must be used to signal the end of the string. For example, to set 440 two -D options on MS-DOS, you must have a dollar sign between them, 441 like this: 442 443 LESS="-Dn9.1$-Ds4.1" 444 445 446 -? or --help 447 This option displays a summary of the commands accepted by [4mless[0m 448 (the same as the h command). (Depending on how your shell 449 interprets the question mark, it may be necessary to quote the 450 question mark, thus: "-\?".) 451 452 -a or --search-skip-screen 453 Causes searches to start after the last line displayed on the 454 screen, thus skipping all lines displayed on the screen. By 455 default, searches start at the second line on the screen (or 456 after the last found line; see the -j option). 457 458 -b[4mn[24m or --buffers=[4mn[0m 459 Specifies the amount of buffer space [4mless[24m will use for each 460 file, in units of kilobytes (1024 bytes). By default 64K of 461 buffer space is used for each file (unless the file is a pipe; 462 see the -B option). The -b option specifies instead that [4mn[0m 463 kilobytes of buffer space should be used for each file. If [4mn[24m is 464 -1, buffer space is unlimited; that is, the entire file can be 465 read into memory. 466 467 -B or --auto-buffers 468 By default, when data is read from a pipe, buffers are allocated 469 automatically as needed. If a large amount of data is read from 470 the pipe, this can cause a large amount of memory to be allo- 471 cated. The -B option disables this automatic allocation of 472 buffers for pipes, so that only 64K (or the amount of space 473 specified by the -b option) is used for the pipe. Warning: use 474 of -B can result in erroneous display, since only the most 475 recently viewed part of the piped data is kept in memory; any 476 earlier data is lost. 477 478 -c or --clear-screen 479 Causes full screen repaints to be painted from the top line 480 down. By default, full screen repaints are done by scrolling 481 from the bottom of the screen. 482 483 -C or --CLEAR-SCREEN 484 Same as -c, for compatibility with older versions of [4mless.[0m 485 486 -d or --dumb 487 The -d option suppresses the error message normally displayed if 488 the terminal is dumb; that is, lacks some important capability, 489 such as the ability to clear the screen or scroll backward. The 490 -d option does not otherwise change the behavior of [4mless[24m on a 491 dumb terminal. 492 493 -D[1mx[4m[22mcolor[24m or --color=[1mx[4m[22mcolor[0m 494 [MS-DOS only] Sets the color of the text displayed. [1mx [22mis a sin- 495 gle character which selects the type of text whose color is 496 being set: n=normal, s=standout, d=bold, u=underlined, k=blink. 497 [4mcolor[24m is a pair of numbers separated by a period. The first 498 number selects the foreground color and the second selects the 499 background color of the text. A single number [4mN[24m is the same as 500 [4mN.M[24m, where [4mM[24m is the normal background color. 501 502 503 -e or --quit-at-eof 504 Causes [4mless[24m to automatically exit the second time it reaches 505 end-of-file. By default, the only way to exit [4mless[24m is via the 506 "q" command. 507 508 -E or --QUIT-AT-EOF 509 Causes [4mless[24m to automatically exit the first time it reaches end- 510 of-file. 511 512 -f or --force 513 Forces non-regular files to be opened. (A non-regular file is a 514 directory or a device special file.) Also suppresses the warn- 515 ing message when a binary file is opened. By default, [4mless[24m will 516 refuse to open non-regular files. Note that some operating sys- 517 tems will not allow directories to be read, even if -f is set. 518 519 -F or --quit-if-one-screen 520 Causes [4mless[24m to automatically exit if the entire file can be dis- 521 played on the first screen. 522 523 -g or --hilite-search 524 Normally, [4mless[24m will highlight ALL strings which match the last 525 search command. The -g option changes this behavior to high- 526 light only the particular string which was found by the last 527 search command. This can cause [4mless[24m to run somewhat faster than 528 the default. 529 530 -G or --HILITE-SEARCH 531 The -G option suppresses all highlighting of strings found by 532 search commands. 533 534 -h[4mn[24m or --max-back-scroll=[4mn[0m 535 Specifies a maximum number of lines to scroll backward. If it 536 is necessary to scroll backward more than [4mn[24m lines, the screen is 537 repainted in a forward direction instead. (If the terminal does 538 not have the ability to scroll backward, -h0 is implied.) 539 540 -i or --ignore-case 541 Causes searches to ignore case; that is, uppercase and lowercase 542 are considered identical. This option is ignored if any upper- 543 case letters appear in the search pattern; in other words, if a 544 pattern contains uppercase letters, then that search does not 545 ignore case. 546 547 -I or --IGNORE-CASE 548 Like -i, but searches ignore case even if the pattern contains 549 uppercase letters. 550 551 -j[4mn[24m or --jump-target=[4mn[0m 552 Specifies a line on the screen where the "target" line is to be 553 positioned. The target line is the line specified by any com- 554 mand to search for a pattern, jump to a line number, jump to a 555 file percentage or jump to a tag. The screen line may be speci- 556 fied by a number: the top line on the screen is 1, the next is 557 2, and so on. The number may be negative to specify a line rel- 558 ative to the bottom of the screen: the bottom line on the screen 559 is -1, the second to the bottom is -2, and so on. Alternately, 560 the screen line may be specified as a fraction of the height of 561 the screen, starting with a decimal point: .5 is in the middle 562 of the screen, .3 is three tenths down from the first line, and 563 so on. If the line is specified as a fraction, the actual line 564 number is recalculated if the terminal window is resized, so 565 that the target line remains at the specified fraction of the 566 screen height. If any form of the -j option is used, forward 567 searches begin at the line immediately after the target line, 568 and backward searches begin at the target line. For example, if 569 "-j4" is used, the target line is the fourth line on the screen, 570 so forward searches begin at the fifth line on the screen. 571 572 -J or --status-column 573 Displays a status column at the left edge of the screen. The 574 status column shows the lines that matched the current search. 575 The status column is also used if the -w or -W option is in 576 effect. 577 578 -k[4mfilename[24m or --lesskey-file=[4mfilename[0m 579 Causes [4mless[24m to open and interpret the named file as a [4mlesskey[0m 580 (1) file. Multiple -k options may be specified. If the LESSKEY 581 or LESSKEY_SYSTEM environment variable is set, or if a lesskey 582 file is found in a standard place (see KEY BINDINGS), it is also 583 used as a [4mlesskey[24m file. 584 585 -K or --quit-on-intr 586 Causes [4mless[24m to exit immediately when an interrupt character 587 (usually ^C) is typed. Normally, an interrupt character causes 588 [4mless[24m to stop whatever it is doing and return to its command 589 prompt. Note that use of this option makes it impossible to 590 return to the command prompt from the "F" command. 591 592 -L or --no-lessopen 593 Ignore the LESSOPEN environment variable (see the INPUT PRE- 594 PROCESSOR section below). This option can be set from within 595 [4mless[24m, but it will apply only to files opened subsequently, not 596 to the file which is currently open. 597 598 -m or --long-prompt 599 Causes [4mless[24m to prompt verbosely (like [4mmore[24m), with the percent 600 into the file. By default, [4mless[24m prompts with a colon. 601 602 -M or --LONG-PROMPT 603 Causes [4mless[24m to prompt even more verbosely than [4mmore.[0m 604 605 -n or --line-numbers 606 Suppresses line numbers. The default (to use line numbers) may 607 cause [4mless[24m to run more slowly in some cases, especially with a 608 very large input file. Suppressing line numbers with the -n 609 option will avoid this problem. Using line numbers means: the 610 line number will be displayed in the verbose prompt and in the = 611 command, and the v command will pass the current line number to 612 the editor (see also the discussion of LESSEDIT in PROMPTS 613 below). 614 615 -N or --LINE-NUMBERS 616 Causes a line number to be displayed at the beginning of each 617 line in the display. 618 619 -o[4mfilename[24m or --log-file=[4mfilename[0m 620 Causes [4mless[24m to copy its input to the named file as it is being 621 viewed. This applies only when the input file is a pipe, not an 622 ordinary file. If the file already exists, [4mless[24m will ask for 623 confirmation before overwriting it. 624 625 -O[4mfilename[24m or --LOG-FILE=[4mfilename[0m 626 The -O option is like -o, but it will overwrite an existing file 627 without asking for confirmation. 628 629 If no log file has been specified, the -o and -O options can be 630 used from within [4mless[24m to specify a log file. Without a file 631 name, they will simply report the name of the log file. The "s" 632 command is equivalent to specifying -o from within [4mless.[0m 633 634 -p[4mpattern[24m or --pattern=[4mpattern[0m 635 The -p option on the command line is equivalent to specifying 636 +/[4mpattern[24m; that is, it tells [4mless[24m to start at the first occur- 637 rence of [4mpattern[24m in the file. 638 639 -P[4mprompt[24m or --prompt=[4mprompt[0m 640 Provides a way to tailor the three prompt styles to your own 641 preference. This option would normally be put in the LESS envi- 642 ronment variable, rather than being typed in with each [4mless[24m com- 643 mand. Such an option must either be the last option in the LESS 644 variable, or be terminated by a dollar sign. -Ps followed by a 645 string changes the default (short) prompt to that string. -Pm 646 changes the medium (-m) prompt. -PM changes the long (-M) 647 prompt. -Ph changes the prompt for the help screen. -P= 648 changes the message printed by the = command. -Pw changes the 649 message printed while waiting for data (in the F command). All 650 prompt strings consist of a sequence of letters and special 651 escape sequences. See the section on PROMPTS for more details. 652 653 -q or --quiet or --silent 654 Causes moderately "quiet" operation: the terminal bell is not 655 rung if an attempt is made to scroll past the end of the file or 656 before the beginning of the file. If the terminal has a "visual 657 bell", it is used instead. The bell will be rung on certain 658 other errors, such as typing an invalid character. The default 659 is to ring the terminal bell in all such cases. 660 661 -Q or --QUIET or --SILENT 662 Causes totally "quiet" operation: the terminal bell is never 663 rung. 664 665 -r or --raw-control-chars 666 Causes "raw" control characters to be displayed. The default is 667 to display control characters using the caret notation; for 668 example, a control-A (octal 001) is displayed as "^A". Warning: 669 when the -r option is used, [4mless[24m cannot keep track of the actual 670 appearance of the screen (since this depends on how the screen 671 responds to each type of control character). Thus, various dis- 672 play problems may result, such as long lines being split in the 673 wrong place. 674 675 -R or --RAW-CONTROL-CHARS 676 Like -r, but only ANSI "color" escape sequences are output in 677 "raw" form. Unlike -r, the screen appearance is maintained cor- 678 rectly in most cases. ANSI "color" escape sequences are 679 sequences of the form: 680 681 ESC [ ... m 682 683 where the "..." is zero or more color specification characters 684 For the purpose of keeping track of screen appearance, ANSI 685 color escape sequences are assumed to not move the cursor. You 686 can make [4mless[24m think that characters other than "m" can end ANSI 687 color escape sequences by setting the environment variable 688 LESSANSIENDCHARS to the list of characters which can end a color 689 escape sequence. And you can make [4mless[24m think that characters 690 other than the standard ones may appear between the ESC and the 691 m by setting the environment variable LESSANSIMIDCHARS to the 692 list of characters which can appear. 693 694 -s or --squeeze-blank-lines 695 Causes consecutive blank lines to be squeezed into a single 696 blank line. This is useful when viewing [4mnroff[24m output. 697 698 -S or --chop-long-lines 699 Causes lines longer than the screen width to be chopped rather 700 than folded. That is, the portion of a long line that does not 701 fit in the screen width is not shown. The default is to fold 702 long lines; that is, display the remainder on the next line. 703 704 -t[4mtag[24m or --tag=[4mtag[0m 705 The -t option, followed immediately by a TAG, will edit the file 706 containing that tag. For this to work, tag information must be 707 available; for example, there may be a file in the current 708 directory called "tags", which was previously built by [4mctags[24m (1) 709 or an equivalent command. If the environment variable LESSGLOB- 710 ALTAGS is set, it is taken to be the name of a command compati- 711 ble with [4mglobal[24m (1), and that command is executed to find the 712 tag. (See http://www.gnu.org/software/global/global.html). The 713 -t option may also be specified from within [4mless[24m (using the - 714 command) as a way of examining a new file. The command ":t" is 715 equivalent to specifying -t from within [4mless.[0m 716 717 -T[4mtagsfile[24m or --tag-file=[4mtagsfile[0m 718 Specifies a tags file to be used instead of "tags". 719 720 -u or --underline-special 721 Causes backspaces and carriage returns to be treated as print- 722 able characters; that is, they are sent to the terminal when 723 they appear in the input. 724 725 -U or --UNDERLINE-SPECIAL 726 Causes backspaces, tabs and carriage returns to be treated as 727 control characters; that is, they are handled as specified by 728 the -r option. 729 730 By default, if neither -u nor -U is given, backspaces which 731 appear adjacent to an underscore character are treated spe- 732 cially: the underlined text is displayed using the terminal's 733 hardware underlining capability. Also, backspaces which appear 734 between two identical characters are treated specially: the 735 overstruck text is printed using the terminal's hardware bold- 736 face capability. Other backspaces are deleted, along with the 737 preceding character. Carriage returns immediately followed by a 738 newline are deleted. other carriage returns are handled as 739 specified by the -r option. Text which is overstruck or under- 740 lined can be searched for if neither -u nor -U is in effect. 741 742 -V or --version 743 Displays the version number of [4mless.[0m 744 745 -w or --hilite-unread 746 Temporarily highlights the first "new" line after a forward 747 movement of a full page. The first "new" line is the line imme- 748 diately following the line previously at the bottom of the 749 screen. Also highlights the target line after a g or p command. 750 The highlight is removed at the next command which causes move- 751 ment. The entire line is highlighted, unless the -J option is 752 in effect, in which case only the status column is highlighted. 753 754 -W or --HILITE-UNREAD 755 Like -w, but temporarily highlights the first new line after any 756 forward movement command larger than one line. 757 758 -x[4mn[24m,... or --tabs=[4mn[24m,... 759 Sets tab stops. If only one [4mn[24m is specified, tab stops are set 760 at multiples of [4mn[24m. If multiple values separated by commas are 761 specified, tab stops are set at those positions, and then con- 762 tinue with the same spacing as the last two. For example, 763 [4m-x9,17[24m will set tabs at positions 9, 17, 25, 33, etc. The 764 default for [4mn[24m is 8. 765 766 -X or --no-init 767 Disables sending the termcap initialization and deinitialization 768 strings to the terminal. This is sometimes desirable if the 769 deinitialization string does something unnecessary, like clear- 770 ing the screen. 771 772 -y[4mn[24m or --max-forw-scroll=[4mn[0m 773 Specifies a maximum number of lines to scroll forward. If it is 774 necessary to scroll forward more than [4mn[24m lines, the screen is 775 repainted instead. The -c or -C option may be used to repaint 776 from the top of the screen if desired. By default, any forward 777 movement causes scrolling. 778 779 -[z][4mn[24m or --window=[4mn[0m 780 Changes the default scrolling window size to [4mn[24m lines. The 781 default is one screenful. The z and w commands can also be used 782 to change the window size. The "z" may be omitted for compati- 783 bility with some versions of [4mmore.[24m If the number [4mn[24m is negative, 784 it indicates [4mn[24m lines less than the current screen size. For 785 example, if the screen is 24 lines, [4m-z-4[24m sets the scrolling win- 786 dow to 20 lines. If the screen is resized to 40 lines, the 787 scrolling window automatically changes to 36 lines. 788 789 -[4m"cc[24m or --quotes=[4mcc[0m 790 Changes the filename quoting character. This may be necessary 791 if you are trying to name a file which contains both spaces and 792 quote characters. Followed by a single character, this changes 793 the quote character to that character. Filenames containing a 794 space should then be surrounded by that character rather than by 795 double quotes. Followed by two characters, changes the open 796 quote to the first character, and the close quote to the second 797 character. Filenames containing a space should then be preceded 798 by the open quote character and followed by the close quote 799 character. Note that even after the quote characters are 800 changed, this option remains -" (a dash followed by a double 801 quote). 802 803 -~ or --tilde 804 Normally lines after end of file are displayed as a single tilde 805 (~). This option causes lines after end of file to be displayed 806 as blank lines. 807 808 -# or --shift 809 Specifies the default number of positions to scroll horizontally 810 in the RIGHTARROW and LEFTARROW commands. If the number speci- 811 fied is zero, it sets the default number of positions to one 812 half of the screen width. Alternately, the number may be speci- 813 fied as a fraction of the width of the screen, starting with a 814 decimal point: .5 is half of the screen width, .3 is three 815 tenths of the screen width, and so on. If the number is speci- 816 fied as a fraction, the actual number of scroll positions is 817 recalculated if the terminal window is resized, so that the 818 actual scroll remains at the specified fraction of the screen 819 width. 820 821 --no-keypad 822 Disables sending the keypad initialization and deinitialization 823 strings to the terminal. This is sometimes useful if the keypad 824 strings make the numeric keypad behave in an undesirable manner. 825 826 --follow-name 827 Normally, if the input file is renamed while an F command is 828 executing, [4mless[24m will continue to display the contents of the 829 original file despite its name change. If --follow-name is 830 specified, during an F command [4mless[24m will periodically attempt to 831 reopen the file by name. If the reopen succeeds and the file is 832 a different file from the original (which means that a new file 833 has been created with the same name as the original (now 834 renamed) file), [4mless[24m will display the contents of that new file. 835 836 -- A command line argument of "--" marks the end of option argu- 837 ments. Any arguments following this are interpreted as file- 838 names. This can be useful when viewing a file whose name begins 839 with a "-" or "+". 840 841 + If a command line option begins with [1m+[22m, the remainder of that 842 option is taken to be an initial command to [4mless.[24m For example, 843 +G tells [4mless[24m to start at the end of the file rather than the 844 beginning, and +/xyz tells it to start at the first occurrence 845 of "xyz" in the file. As a special case, +<number> acts like 846 +<number>g; that is, it starts the display at the specified line 847 number (however, see the caveat under the "g" command above). 848 If the option starts with ++, the initial command applies to 849 every file being viewed, not just the first one. The + command 850 described previously may also be used to set (or change) an ini- 851 tial command for every file. 852 853 854[1mLINE EDITING[0m 855 When entering command line at the bottom of the screen (for example, a 856 filename for the :e command, or the pattern for a search command), cer- 857 tain keys can be used to manipulate the command line. Most commands 858 have an alternate form in [ brackets ] which can be used if a key does 859 not exist on a particular keyboard. (Note that the forms beginning 860 with ESC do not work in some MS-DOS and Windows systems because ESC is 861 the line erase character.) Any of these special keys may be entered 862 literally by preceding it with the "literal" character, either ^V or 863 ^A. A backslash itself may also be entered literally by entering two 864 backslashes. 865 866 LEFTARROW [ ESC-h ] 867 Move the cursor one space to the left. 868 869 RIGHTARROW [ ESC-l ] 870 Move the cursor one space to the right. 871 872 ^LEFTARROW [ ESC-b or ESC-LEFTARROW ] 873 (That is, CONTROL and LEFTARROW simultaneously.) Move the cur- 874 sor one word to the left. 875 876 ^RIGHTARROW [ ESC-w or ESC-RIGHTARROW ] 877 (That is, CONTROL and RIGHTARROW simultaneously.) Move the cur- 878 sor one word to the right. 879 880 HOME [ ESC-0 ] 881 Move the cursor to the beginning of the line. 882 883 END [ ESC-$ ] 884 Move the cursor to the end of the line. 885 886 BACKSPACE 887 Delete the character to the left of the cursor, or cancel the 888 command if the command line is empty. 889 890 DELETE or [ ESC-x ] 891 Delete the character under the cursor. 892 893 ^BACKSPACE [ ESC-BACKSPACE ] 894 (That is, CONTROL and BACKSPACE simultaneously.) Delete the 895 word to the left of the cursor. 896 897 ^DELETE [ ESC-X or ESC-DELETE ] 898 (That is, CONTROL and DELETE simultaneously.) Delete the word 899 under the cursor. 900 901 UPARROW [ ESC-k ] 902 Retrieve the previous command line. 903 904 DOWNARROW [ ESC-j ] 905 Retrieve the next command line. 906 907 TAB Complete the partial filename to the left of the cursor. If it 908 matches more than one filename, the first match is entered into 909 the command line. Repeated TABs will cycle thru the other 910 matching filenames. If the completed filename is a directory, a 911 "/" is appended to the filename. (On MS-DOS systems, a "\" is 912 appended.) The environment variable LESSSEPARATOR can be used 913 to specify a different character to append to a directory name. 914 915 BACKTAB [ ESC-TAB ] 916 Like, TAB, but cycles in the reverse direction thru the matching 917 filenames. 918 919 ^L Complete the partial filename to the left of the cursor. If it 920 matches more than one filename, all matches are entered into the 921 command line (if they fit). 922 923 ^U (Unix and OS/2) or ESC (MS-DOS) 924 Delete the entire command line, or cancel the command if the 925 command line is empty. If you have changed your line-kill char- 926 acter in Unix to something other than ^U, that character is used 927 instead of ^U. 928 929 930[1mKEY BINDINGS[0m 931 You may define your own [4mless[24m commands by using the program [4mlesskey[24m (1) 932 to create a lesskey file. This file specifies a set of command keys 933 and an action associated with each key. You may also use [4mlesskey[24m to 934 change the line-editing keys (see LINE EDITING), and to set environment 935 variables. If the environment variable LESSKEY is set, [4mless[24m uses that 936 as the name of the lesskey file. Otherwise, [4mless[24m looks in a standard 937 place for the lesskey file: On Unix systems, [4mless[24m looks for a lesskey 938 file called "$HOME/.less". On MS-DOS and Windows systems, [4mless[24m looks 939 for a lesskey file called "$HOME/_less", and if it is not found there, 940 then looks for a lesskey file called "_less" in any directory specified 941 in the PATH environment variable. On OS/2 systems, [4mless[24m looks for a 942 lesskey file called "$HOME/less.ini", and if it is not found, then 943 looks for a lesskey file called "less.ini" in any directory specified 944 in the INIT environment variable, and if it not found there, then looks 945 for a lesskey file called "less.ini" in any directory specified in the 946 PATH environment variable. See the [4mlesskey[24m manual page for more 947 details. 948 949 A system-wide lesskey file may also be set up to provide key bindings. 950 If a key is defined in both a local lesskey file and in the system-wide 951 file, key bindings in the local file take precedence over those in the 952 system-wide file. If the environment variable LESSKEY_SYSTEM is set, 953 [4mless[24m uses that as the name of the system-wide lesskey file. Otherwise, 954 [4mless[24m looks in a standard place for the system-wide lesskey file: On 955 Unix systems, the system-wide lesskey file is /usr/local/etc/sysless. 956 (However, if [4mless[24m was built with a different sysconf directory than 957 /usr/local/etc, that directory is where the sysless file is found.) On 958 MS-DOS and Windows systems, the system-wide lesskey file is c:\_sys- 959 less. On OS/2 systems, the system-wide lesskey file is c:\sysless.ini. 960 961 962[1mINPUT PREPROCESSOR[0m 963 You may define an "input preprocessor" for [4mless.[24m Before [4mless[24m opens a 964 file, it first gives your input preprocessor a chance to modify the way 965 the contents of the file are displayed. An input preprocessor is sim- 966 ply an executable program (or shell script), which writes the contents 967 of the file to a different file, called the replacement file. The con- 968 tents of the replacement file are then displayed in place of the con- 969 tents of the original file. However, it will appear to the user as if 970 the original file is opened; that is, [4mless[24m will display the original 971 filename as the name of the current file. 972 973 An input preprocessor receives one command line argument, the original 974 filename, as entered by the user. It should create the replacement 975 file, and when finished, print the name of the replacement file to its 976 standard output. If the input preprocessor does not output a replace- 977 ment filename, [4mless[24m uses the original file, as normal. The input pre- 978 processor is not called when viewing standard input. To set up an 979 input preprocessor, set the LESSOPEN environment variable to a command 980 line which will invoke your input preprocessor. This command line 981 should include one occurrence of the string "%s", which will be 982 replaced by the filename when the input preprocessor command is 983 invoked. 984 985 When [4mless[24m closes a file opened in such a way, it will call another pro- 986 gram, called the input postprocessor, which may perform any desired 987 clean-up action (such as deleting the replacement file created by 988 LESSOPEN). This program receives two command line arguments, the orig- 989 inal filename as entered by the user, and the name of the replacement 990 file. To set up an input postprocessor, set the LESSCLOSE environment 991 variable to a command line which will invoke your input postprocessor. 992 It may include two occurrences of the string "%s"; the first is 993 replaced with the original name of the file and the second with the 994 name of the replacement file, which was output by LESSOPEN. 995 996 For example, on many Unix systems, these two scripts will allow you to 997 keep files in compressed format, but still let [4mless[24m view them directly: 998 999 lessopen.sh: 1000 #! /bin/sh 1001 case "$1" in 1002 *.Z) uncompress - 1003 if [ -s /tmp/less.$$ ]; then 1004 echo /tmp/less.$$ 1005 else 1006 rm -f /tmp/less.$$ 1007 fi 1008 ;; 1009 esac 1010 1011 lessclose.sh: 1012 #! /bin/sh 1013 rm $2 1014 1015 To use these scripts, put them both where they can be executed and set 1016 LESSOPEN="lessopen.sh %s", and LESSCLOSE="lessclose.sh %s %s". More 1017 complex LESSOPEN and LESSCLOSE scripts may be written to accept other 1018 types of compressed files, and so on. 1019 1020 It is also possible to set up an input preprocessor to pipe the file 1021 data directly to [4mless,[24m rather than putting the data into a replacement 1022 file. This avoids the need to decompress the entire file before start- 1023 ing to view it. An input preprocessor that works this way is called an 1024 input pipe. An input pipe, instead of writing the name of a replace- 1025 ment file on its standard output, writes the entire contents of the 1026 replacement file on its standard output. If the input pipe does not 1027 write any characters on its standard output, then there is no replace- 1028 ment file and [4mless[24m uses the original file, as normal. To use an input 1029 pipe, make the first character in the LESSOPEN environment variable a 1030 vertical bar (|) to signify that the input preprocessor is an input 1031 pipe. 1032 1033 For example, on many Unix systems, this script will work like the pre- 1034 vious example scripts: 1035 1036 lesspipe.sh: 1037 #! /bin/sh 1038 case "$1" in 1039 *.Z) uncompress -c $1 2>/dev/null 1040 ;; 1041 esac 1042 1043 To use this script, put it where it can be executed and set 1044 LESSOPEN="|lesspipe.sh %s". When an input pipe is used, a LESSCLOSE 1045 postprocessor can be used, but it is usually not necessary since there 1046 is no replacement file to clean up. In this case, the replacement file 1047 name passed to the LESSCLOSE postprocessor is "-". 1048 1049 For compatibility with previous versions of [4mless,[24m the input preproces- 1050 sor or pipe is not used if [4mless[24m is viewing standard input. However, if 1051 the first character of LESSOPEN is a dash (-), the input preprocessor 1052 is used on standard input as well as other files. In this case, the 1053 dash is not considered to be part of the preprocessor command. If 1054 standard input is being viewed, the input preprocessor is passed a file 1055 name consisting of a single dash. Similarly, if the first two charac- 1056 ters of LESSOPEN are vertical bar and dash (|-), the input pipe is used 1057 on standard input as well as other files. Again, in this case the dash 1058 is not considered to be part of the input pipe command. 1059 1060 1061[1mNATIONAL CHARACTER SETS[0m 1062 There are three types of characters in the input file: 1063 1064 normal characters 1065 can be displayed directly to the screen. 1066 1067 control characters 1068 should not be displayed directly, but are expected to be found 1069 in ordinary text files (such as backspace and tab). 1070 1071 binary characters 1072 should not be displayed directly and are not expected to be 1073 found in text files. 1074 1075 A "character set" is simply a description of which characters are to be 1076 considered normal, control, and binary. The LESSCHARSET environment 1077 variable may be used to select a character set. Possible values for 1078 LESSCHARSET are: 1079 1080 ascii BS, TAB, NL, CR, and formfeed are control characters, all chars 1081 with values between 32 and 126 are normal, and all others are 1082 binary. 1083 1084 iso8859 1085 Selects an ISO 8859 character set. This is the same as ASCII, 1086 except characters between 160 and 255 are treated as normal 1087 characters. 1088 1089 latin1 Same as iso8859. 1090 1091 latin9 Same as iso8859. 1092 1093 dos Selects a character set appropriate for MS-DOS. 1094 1095 ebcdic Selects an EBCDIC character set. 1096 1097 IBM-1047 1098 Selects an EBCDIC character set used by OS/390 Unix Services. 1099 This is the EBCDIC analogue of latin1. You get similar results 1100 by setting either LESSCHARSET=IBM-1047 or LC_CTYPE=en_US in your 1101 environment. 1102 1103 koi8-r Selects a Russian character set. 1104 1105 next Selects a character set appropriate for NeXT computers. 1106 1107 utf-8 Selects the UTF-8 encoding of the ISO 10646 character set. 1108 UTF-8 is special in that it supports multi-byte characters in 1109 the input file. It is the only character set that supports 1110 multi-byte characters. 1111 1112 windows 1113 Selects a character set appropriate for Microsoft Windows (cp 1114 1251). 1115 1116 In rare cases, it may be desired to tailor [4mless[24m to use a character set 1117 other than the ones definable by LESSCHARSET. In this case, the envi- 1118 ronment variable LESSCHARDEF can be used to define a character set. It 1119 should be set to a string where each character in the string represents 1120 one character in the character set. The character "." is used for a 1121 normal character, "c" for control, and "b" for binary. A decimal num- 1122 ber may be used for repetition. For example, "bccc4b." would mean 1123 character 0 is binary, 1, 2 and 3 are control, 4, 5, 6 and 7 are 1124 binary, and 8 is normal. All characters after the last are taken to be 1125 the same as the last, so characters 9 through 255 would be normal. 1126 (This is an example, and does not necessarily represent any real char- 1127 acter set.) 1128 1129 This table shows the value of LESSCHARDEF which is equivalent to each 1130 of the possible values for LESSCHARSET: 1131 1132 ascii 8bcccbcc18b95.b 1133 dos 8bcccbcc12bc5b95.b. 1134 ebcdic 5bc6bcc7bcc41b.9b7.9b5.b..8b6.10b6.b9.7b 1135 9.8b8.17b3.3b9.7b9.8b8.6b10.b.b.b. 1136 IBM-1047 4cbcbc3b9cbccbccbb4c6bcc5b3cbbc4bc4bccbc 1137 191.b 1138 iso8859 8bcccbcc18b95.33b. 1139 koi8-r 8bcccbcc18b95.b128. 1140 latin1 8bcccbcc18b95.33b. 1141 next 8bcccbcc18b95.bb125.bb 1142 1143 If neither LESSCHARSET nor LESSCHARDEF is set, but any of the strings 1144 "UTF-8", "UTF8", "utf-8" or "utf8" is found in the LC_ALL, LC_TYPE or 1145 LANG environment variables, then the default character set is utf-8. 1146 1147 If that string is not found, but your system supports the [4msetlocale[0m 1148 interface, [4mless[24m will use setlocale to determine the character set. 1149 setlocale is controlled by setting the LANG or LC_CTYPE environment 1150 variables. 1151 1152 Finally, if the [4msetlocale[24m interface is also not available, the default 1153 character set is latin1. 1154 1155 Control and binary characters are displayed in standout (reverse 1156 video). Each such character is displayed in caret notation if possible 1157 (e.g. ^A for control-A). Caret notation is used only if inverting the 1158 0100 bit results in a normal printable character. Otherwise, the char- 1159 acter is displayed as a hex number in angle brackets. This format can 1160 be changed by setting the LESSBINFMT environment variable. LESSBINFMT 1161 may begin with a "*" and one character to select the display attribute: 1162 "*k" is blinking, "*d" is bold, "*u" is underlined, "*s" is standout, 1163 and "*n" is normal. If LESSBINFMT does not begin with a "*", normal 1164 attribute is assumed. The remainder of LESSBINFMT is a string which 1165 may include one printf-style escape sequence (a % followed by x, X, o, 1166 d, etc.). For example, if LESSBINFMT is "*u[%x]", binary characters 1167 are displayed in underlined hexadecimal surrounded by brackets. The 1168 default if no LESSBINFMT is specified is "*s<%X>". The default if no 1169 LESSBINFMT is specified is "*s<%02X>". Warning: the result of expand- 1170 ing the character via LESSBINFMT must be less than 31 characters. 1171 1172 When the character set is utf-8, the LESSUTFBINFMT environment variable 1173 acts similarly to LESSBINFMT but it applies to Unicode code points that 1174 were successfully decoded but are unsuitable for display (e.g., unas- 1175 signed code points). Its default value is "<U+%04lX>". Note that 1176 LESSUTFBINFMT and LESSBINFMT share their display attribute setting 1177 ("*x") so specifying one will affect both; LESSUTFBINFMT is read after 1178 LESSBINFMT so its setting, if any, will have priority. Problematic 1179 octets in a UTF-8 file (octets of a truncated sequence, octets of a 1180 complete but non-shortest form sequence, illegal octets, and stray 1181 trailing octets) are displayed individually using LESSBINFMT so as to 1182 facilitate diagnostic of how the UTF-8 file is ill-formed. 1183 1184 1185[1mPROMPTS[0m 1186 The -P option allows you to tailor the prompt to your preference. The 1187 string given to the -P option replaces the specified prompt string. 1188 Certain characters in the string are interpreted specially. The prompt 1189 mechanism is rather complicated to provide flexibility, but the ordi- 1190 nary user need not understand the details of constructing personalized 1191 prompt strings. 1192 1193 A percent sign followed by a single character is expanded according to 1194 what the following character is: 1195 1196 %b[4mX[24m Replaced by the byte offset into the current input file. The b 1197 is followed by a single character (shown as [4mX[24m above) which spec- 1198 ifies the line whose byte offset is to be used. If the charac- 1199 ter is a "t", the byte offset of the top line in the display is 1200 used, an "m" means use the middle line, a "b" means use the bot- 1201 tom line, a "B" means use the line just after the bottom line, 1202 and a "j" means use the "target" line, as specified by the -j 1203 option. 1204 1205 %B Replaced by the size of the current input file. 1206 1207 %c Replaced by the column number of the text appearing in the first 1208 column of the screen. 1209 1210 %d[4mX[24m Replaced by the page number of a line in the input file. The 1211 line to be used is determined by the [4mX[24m, as with the %b option. 1212 1213 %D Replaced by the number of pages in the input file, or equiva- 1214 lently, the page number of the last line in the input file. 1215 1216 %E Replaced by the name of the editor (from the VISUAL environment 1217 variable, or the EDITOR environment variable if VISUAL is not 1218 defined). See the discussion of the LESSEDIT feature below. 1219 1220 %f Replaced by the name of the current input file. 1221 1222 %i Replaced by the index of the current file in the list of input 1223 files. 1224 1225 %l[4mX[24m Replaced by the line number of a line in the input file. The 1226 line to be used is determined by the [4mX[24m, as with the %b option. 1227 1228 %L Replaced by the line number of the last line in the input file. 1229 1230 %m Replaced by the total number of input files. 1231 1232 %p[4mX[24m Replaced by the percent into the current input file, based on 1233 byte offsets. The line used is determined by the [4mX[24m as with the 1234 %b option. 1235 1236 %P[4mX[24m Replaced by the percent into the current input file, based on 1237 line numbers. The line used is determined by the [4mX[24m as with the 1238 %b option. 1239 1240 %s Same as %B. 1241 1242 %t Causes any trailing spaces to be removed. Usually used at the 1243 end of the string, but may appear anywhere. 1244 1245 %x Replaced by the name of the next input file in the list. 1246 1247 If any item is unknown (for example, the file size if input is a pipe), 1248 a question mark is printed instead. 1249 1250 The format of the prompt string can be changed depending on certain 1251 conditions. A question mark followed by a single character acts like 1252 an "IF": depending on the following character, a condition is evalu- 1253 ated. If the condition is true, any characters following the question 1254 mark and condition character, up to a period, are included in the 1255 prompt. If the condition is false, such characters are not included. 1256 A colon appearing between the question mark and the period can be used 1257 to establish an "ELSE": any characters between the colon and the period 1258 are included in the string if and only if the IF condition is false. 1259 Condition characters (which follow a question mark) may be: 1260 1261 ?a True if any characters have been included in the prompt so far. 1262 1263 ?b[4mX[24m True if the byte offset of the specified line is known. 1264 1265 ?B True if the size of current input file is known. 1266 1267 ?c True if the text is horizontally shifted (%c is not zero). 1268 1269 ?d[4mX[24m True if the page number of the specified line is known. 1270 1271 ?e True if at end-of-file. 1272 1273 ?f True if there is an input filename (that is, if input is not a 1274 pipe). 1275 1276 ?l[4mX[24m True if the line number of the specified line is known. 1277 1278 ?L True if the line number of the last line in the file is known. 1279 1280 ?m True if there is more than one input file. 1281 1282 ?n True if this is the first prompt in a new input file. 1283 1284 ?p[4mX[24m True if the percent into the current input file, based on byte 1285 offsets, of the specified line is known. 1286 1287 ?P[4mX[24m True if the percent into the current input file, based on line 1288 numbers, of the specified line is known. 1289 1290 ?s Same as "?B". 1291 1292 ?x True if there is a next input file (that is, if the current 1293 input file is not the last one). 1294 1295 Any characters other than the special ones (question mark, colon, 1296 period, percent, and backslash) become literally part of the prompt. 1297 Any of the special characters may be included in the prompt literally 1298 by preceding it with a backslash. 1299 1300 Some examples: 1301 1302 ?f%f:Standard input. 1303 1304 This prompt prints the filename, if known; otherwise the string "Stan- 1305 dard input". 1306 1307 ?f%f .?ltLine %lt:?pt%pt\%:?btByte %bt:-... 1308 1309 This prompt would print the filename, if known. The filename is fol- 1310 lowed by the line number, if known, otherwise the percent if known, 1311 otherwise the byte offset if known. Otherwise, a dash is printed. 1312 Notice how each question mark has a matching period, and how the % 1313 after the %pt is included literally by escaping it with a backslash. 1314 1315 ?n?f%f .?m(file %i of %m) ..?e(END) ?x- Next\: %x..%t 1316 1317 This prints the filename if this is the first prompt in a file, fol- 1318 lowed by the "file N of N" message if there is more than one input 1319 file. Then, if we are at end-of-file, the string "(END)" is printed 1320 followed by the name of the next file, if there is one. Finally, any 1321 trailing spaces are truncated. This is the default prompt. For refer- 1322 ence, here are the defaults for the other two prompts (-m and -M 1323 respectively). Each is broken into two lines here for readability 1324 only. 1325 1326 ?n?f%f .?m(file %i of %m) ..?e(END) ?x- Next\: %x.: 1327 ?pB%pB\%:byte %bB?s/%s...%t 1328 1329 ?f%f .?n?m(file %i of %m) ..?ltlines %lt-%lb?L/%L. : 1330 byte %bB?s/%s. .?e(END) ?x- Next\: %x.:?pB%pB\%..%t 1331 1332 And here is the default message produced by the = command: 1333 1334 ?f%f .?m(file %i of %m) .?ltlines %lt-%lb?L/%L. . 1335 byte %bB?s/%s. ?e(END) :?pB%pB\%..%t 1336 1337 The prompt expansion features are also used for another purpose: if an 1338 environment variable LESSEDIT is defined, it is used as the command to 1339 be executed when the v command is invoked. The LESSEDIT string is 1340 expanded in the same way as the prompt strings. The default value for 1341 LESSEDIT is: 1342 1343 %E ?lm+%lm. %f 1344 1345 Note that this expands to the editor name, followed by a + and the line 1346 number, followed by the file name. If your editor does not accept the 1347 "+linenumber" syntax, or has other differences in invocation syntax, 1348 the LESSEDIT variable can be changed to modify this default. 1349 1350 1351[1mSECURITY[0m 1352 When the environment variable LESSSECURE is set to 1, [4mless[24m runs in a 1353 "secure" mode. This means these features are disabled: 1354 1355 ! the shell command 1356 1357 | the pipe command 1358 1359 :e the examine command. 1360 1361 v the editing command 1362 1363 s -o log files 1364 1365 -k use of lesskey files 1366 1367 -t use of tags files 1368 1369 metacharacters in filenames, such as * 1370 1371 filename completion (TAB, ^L) 1372 1373 Less can also be compiled to be permanently in "secure" mode. 1374 1375 1376[1mCOMPATIBILITY WITH MORE[0m 1377 If the environment variable LESS_IS_MORE is set to 1, or if the program 1378 is invoked via a file link named "more", [4mless[24m behaves (mostly) in con- 1379 formance with the POSIX "more" command specification. In this mode, 1380 less behaves differently in these ways: 1381 1382 The -e option works differently. If the -e option is not set, [4mless[0m 1383 behaves as if the -E option were set. If the -e option is set, [4mless[0m 1384 behaves as if the -e and -F options were set. 1385 1386 The -m option works differently. If the -m option is not set, the 1387 medium prompt is used, and it is prefixed with the string "--More--". 1388 If the -m option is set, the short prompt is used. 1389 1390 The -n option acts like the -z option. The normal behavior of the -n 1391 option is unavailable in this mode. 1392 1393 The parameter to the -p option is taken to be a [4mless[24m command rather 1394 than a search pattern. 1395 1396 The LESS environment variable is ignored, and the MORE environment 1397 variable is used in its place. 1398 1399 1400[1mENVIRONMENT VARIABLES[0m 1401 Environment variables may be specified either in the system environment 1402 as usual, or in a [4mlesskey[24m (1) file. If environment variables are 1403 defined in more than one place, variables defined in a local lesskey 1404 file take precedence over variables defined in the system environment, 1405 which take precedence over variables defined in the system-wide lesskey 1406 file. 1407 1408 COLUMNS 1409 Sets the number of columns on the screen. Takes precedence over 1410 the number of columns specified by the TERM variable. (But if 1411 you have a windowing system which supports TIOCGWINSZ or 1412 WIOCGETD, the window system's idea of the screen size takes 1413 precedence over the LINES and COLUMNS environment variables.) 1414 1415 EDITOR The name of the editor (used for the v command). 1416 1417 HOME Name of the user's home directory (used to find a lesskey file 1418 on Unix and OS/2 systems). 1419 1420 HOMEDRIVE, HOMEPATH 1421 Concatenation of the HOMEDRIVE and HOMEPATH environment vari- 1422 ables is the name of the user's home directory if the HOME vari- 1423 able is not set (only in the Windows version). 1424 1425 INIT Name of the user's init directory (used to find a lesskey file 1426 on OS/2 systems). 1427 1428 LANG Language for determining the character set. 1429 1430 LC_CTYPE 1431 Language for determining the character set. 1432 1433 LESS Options which are passed to [4mless[24m automatically. 1434 1435 LESSANSIENDCHARS 1436 Characters which may end an ANSI color escape sequence (default 1437 "m"). 1438 1439 LESSANSIMIDCHARS 1440 Characters which may appear between the ESC character and the 1441 end character in an ANSI color escape sequence (default 1442 "0123456789;[?!"'#%()*+ ". 1443 1444 LESSBINFMT 1445 Format for displaying non-printable, non-control characters. 1446 1447 LESSCHARDEF 1448 Defines a character set. 1449 1450 LESSCHARSET 1451 Selects a predefined character set. 1452 1453 LESSCLOSE 1454 Command line to invoke the (optional) input-postprocessor. 1455 1456 LESSECHO 1457 Name of the lessecho program (default "lessecho"). The lessecho 1458 program is needed to expand metacharacters, such as * and ?, in 1459 filenames on Unix systems. 1460 1461 LESSEDIT 1462 Editor prototype string (used for the v command). See discus- 1463 sion under PROMPTS. 1464 1465 LESSGLOBALTAGS 1466 Name of the command used by the -t option to find global tags. 1467 Normally should be set to "global" if your system has the [4mglobal[0m 1468 (1) command. If not set, global tags are not used. 1469 1470 LESSHISTFILE 1471 Name of the history file used to remember search commands and 1472 shell commands between invocations of [4mless.[24m If set to "-" or 1473 "/dev/null", a history file is not used. The default is 1474 "$HOME/.lesshst" on Unix systems, "$HOME/_lesshst" on DOS and 1475 Windows systems, or "$HOME/lesshst.ini" or "$INIT/lesshst.ini" 1476 on OS/2 systems. 1477 1478 LESSHISTSIZE 1479 The maximum number of commands to save in the history file. The 1480 default is 100. 1481 1482 LESSKEY 1483 Name of the default lesskey(1) file. 1484 1485 LESSKEY_SYSTEM 1486 Name of the default system-wide lesskey(1) file. 1487 1488 LESSMETACHARS 1489 List of characters which are considered "metacharacters" by the 1490 shell. 1491 1492 LESSMETAESCAPE 1493 Prefix which less will add before each metacharacter in a com- 1494 mand sent to the shell. If LESSMETAESCAPE is an empty string, 1495 commands containing metacharacters will not be passed to the 1496 shell. 1497 1498 LESSOPEN 1499 Command line to invoke the (optional) input-preprocessor. 1500 1501 LESSSECURE 1502 Runs less in "secure" mode. See discussion under SECURITY. 1503 1504 LESSSEPARATOR 1505 String to be appended to a directory name in filename comple- 1506 tion. 1507 1508 LESSUTFBINFMT 1509 Format for displaying non-printable Unicode code points. 1510 1511 LESS_IS_MORE 1512 Emulate the [4mmore[24m (1) command. 1513 1514 LINES Sets the number of lines on the screen. Takes precedence over 1515 the number of lines specified by the TERM variable. (But if you 1516 have a windowing system which supports TIOCGWINSZ or WIOCGETD, 1517 the window system's idea of the screen size takes precedence 1518 over the LINES and COLUMNS environment variables.) 1519 1520 PATH User's search path (used to find a lesskey file on MS-DOS and 1521 OS/2 systems). 1522 1523 SHELL The shell used to execute the ! command, as well as to expand 1524 filenames. 1525 1526 TERM The type of terminal on which [4mless[24m is being run. 1527 1528 VISUAL The name of the editor (used for the v command). 1529 1530 1531[1mSEE ALSO[0m 1532 lesskey(1) 1533 1534 1535[1mCOPYRIGHT[0m 1536 Copyright (C) 1984-2009 Mark Nudelman 1537 1538 less is part of the GNU project and is free software. You can redis- 1539 tribute it and/or modify it under the terms of either (1) the GNU Gen- 1540 eral Public License as published by the Free Software Foundation; or 1541 (2) the Less License. See the file README in the less distribution for 1542 more details regarding redistribution. You should have received a copy 1543 of the GNU General Public License along with the source for less; see 1544 the file COPYING. If not, write to the Free Software Foundation, 59 1545 Temple Place, Suite 330, Boston, MA 02111-1307, USA. You should also 1546 have received a copy of the Less License; see the file LICENSE. 1547 1548 less is distributed in the hope that it will be useful, but WITHOUT ANY 1549 WARRANTY; without even the implied warranty of MERCHANTABILITY or FIT- 1550 NESS FOR A PARTICULAR PURPOSE. See the GNU General Public License for 1551 more details. 1552 1553 1554[1mAUTHOR[0m 1555 Mark Nudelman <markn@greenwoodsoftware.com> 1556 See http://www.greenwoodsoftware.com/less/bugs.html for the latest list 1557 of known bugs in less. 1558 Send bug reports or comments to the above address or to 1559 bug-less@gnu.org. 1560 For more information, see the less homepage at 1561 http://www.greenwoodsoftware.com/less. 1562 1563 1564 1565 Version 436: 07 Jul 2009 LESS(1) 1566