less.man revision 173932
11553SrgrimesLESS(1) LESS(1) 21553Srgrimes 31553Srgrimes 41553Srgrimes 51553Srgrimes[1mNAME[0m 61553Srgrimes less - opposite of more 71553Srgrimes 81553Srgrimes[1mSYNOPSIS[0m 91553Srgrimes [1mless -?[0m 101553Srgrimes [1mless --help[0m 111553Srgrimes [1mless -V[0m 121553Srgrimes [1mless --version[0m 131553Srgrimes [1mless [-[+]aBcCdeEfFgGiIJKLmMnNqQrRsSuUVwWX~][0m 141553Srgrimes [1m[-b [4m[22mspace[24m[1m] [-h [4m[22mlines[24m[1m] [-j [4m[22mline[24m[1m] [-k [4m[22mkeyfile[24m[1m][0m 151553Srgrimes [1m[-{oO} [4m[22mlogfile[24m[1m] [-p [4m[22mpattern[24m[1m] [-P [4m[22mprompt[24m[1m] [-t [4m[22mtag[24m[1m][0m 161553Srgrimes [1m[-T [4m[22mtagsfile[24m[1m] [-x [4m[22mtab[24m[1m,...] [-y [4m[22mlines[24m[1m] [-[z] [4m[22mlines[24m[1m][0m 171553Srgrimes [1m[-# [4m[22mshift[24m[1m] [+[+][4m[22mcmd[24m[1m] [--] [[4m[22mfilename[24m[1m]...[0m 181553Srgrimes (See the OPTIONS section for alternate option syntax with long option 191553Srgrimes names.) 201553Srgrimes 211553Srgrimes 221553Srgrimes[1mDESCRIPTION[0m 231553Srgrimes [4mLess[24m is a program similar to [4mmore[24m (1), but which allows backward move- 241553Srgrimes ment in the file as well as forward movement. Also, [4mless[24m does not have 251553Srgrimes to read the entire input file before starting, so with large input 261553Srgrimes files it starts up faster than text editors like [4mvi[24m (1). [4mLess[24m uses 271553Srgrimes termcap (or terminfo on some systems), so it can run on a variety of 281553Srgrimes terminals. There is even limited support for hardcopy terminals. (On 291553Srgrimes a hardcopy terminal, lines which should be printed at the top of the 301553Srgrimes screen are prefixed with a caret.) 311553Srgrimes 321553Srgrimes Commands are based on both [4mmore[24m and [4mvi.[24m Commands may be preceded by a 331553Srgrimes decimal number, called N in the descriptions below. The number is used 341553Srgrimes by some commands, as indicated. 3528996Scharnier 361553Srgrimes 371553Srgrimes[1mCOMMANDS[0m 381553Srgrimes In the following descriptions, ^X means control-X. ESC stands for the 391553Srgrimes ESCAPE key; for example ESC-v means the two character sequence 401553Srgrimes "ESCAPE", then "v". 4128996Scharnier 421553Srgrimes h or H Help: display a summary of these commands. If you forget all 4328996Scharnier the other commands, remember this one. 4428996Scharnier 4528996Scharnier SPACE or ^V or f or ^F 461553Srgrimes Scroll forward N lines, default one window (see option -z 471553Srgrimes below). If N is more than the screen size, only the final 481553Srgrimes screenful is displayed. Warning: some systems use ^V as a spe- 4928996Scharnier cial literalization character. 5028996Scharnier 511553Srgrimes z Like SPACE, but if N is specified, it becomes the new window 521553Srgrimes size. 5328996Scharnier 541553Srgrimes ESC-SPACE 5528996Scharnier Like SPACE, but scrolls a full screenful, even if it reaches 561553Srgrimes end-of-file in the process. 571553Srgrimes 581553Srgrimes RETURN or ^N or e or ^E or j or ^J 591553Srgrimes Scroll forward N lines, default 1. The entire N lines are dis- 601553Srgrimes played, even if N is more than the screen size. 611553Srgrimes 621553Srgrimes d or ^D 631553Srgrimes Scroll forward N lines, default one half of the screen size. If 6424428Simp N is specified, it becomes the new default for subsequent d and 651553Srgrimes u commands. 661553Srgrimes 671553Srgrimes b or ^B or ESC-v 681553Srgrimes Scroll backward N lines, default one window (see option -z 691553Srgrimes below). If N is more than the screen size, only the final 701553Srgrimes screenful is displayed. 711553Srgrimes 721553Srgrimes w Like ESC-v, but if N is specified, it becomes the new window 731553Srgrimes size. 748857Srgrimes 7528996Scharnier y or ^Y or ^P or k or ^K 7628996Scharnier Scroll backward N lines, default 1. The entire N lines are dis- 771553Srgrimes played, even if N is more than the screen size. Warning: some 781553Srgrimes systems use ^Y as a special job control character. 7928996Scharnier 8028996Scharnier u or ^U 811553Srgrimes Scroll backward N lines, default one half of the screen size. 821553Srgrimes If N is specified, it becomes the new default for subsequent d 831553Srgrimes and u commands. 841553Srgrimes 851553Srgrimes ESC-) or RIGHTARROW 861553Srgrimes Scroll horizontally right N characters, default half the screen 871553Srgrimes width (see the -# option). If a number N is specified, it 8828996Scharnier becomes the default for future RIGHTARROW and LEFTARROW com- 891553Srgrimes mands. While the text is scrolled, it acts as though the -S 901553Srgrimes option (chop lines) were in effect. 911553Srgrimes 921553Srgrimes ESC-( or LEFTARROW 931553Srgrimes 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 199 current 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 :e [filename] 261 Examine a new file. If the filename is missing, the "current" 262 file (see the :n and :p commands below) from the list of files 263 in the command line is re-examined. A percent sign (%) in the 264 filename is replaced by the name of the current file. A pound 265 sign (#) is replaced by the name of the previously examined 266 file. However, two consecutive percent signs are simply 267 replaced with a single percent sign. This allows you to enter a 268 filename that contains a percent sign in the name. Similarly, 269 two consecutive pound signs are replaced with a single pound 270 sign. The filename is inserted into the command line list of 271 files so that it can be seen by subsequent :n and :p commands. 272 If the filename consists of several files, they are all inserted 273 into the list of files and the first one is examined. If the 274 filename contains one or more spaces, the entire filename should 275 be enclosed in double quotes (also see the -" option). 276 277 ^X^V or E 278 Same as :e. Warning: some systems use ^V as a special literal- 279 ization character. On such systems, you may not be able to use 280 ^V. 281 282 :n Examine the next file (from the list of files given in the com- 283 mand line). If a number N is specified, the N-th next file is 284 examined. 285 286 :p Examine the previous file in the command line list. If a number 287 N is specified, the N-th previous file is examined. 288 289 :x Examine the first file in the command line list. If a number N 290 is specified, the N-th file in the list is examined. 291 292 :d Remove the current file from the list of files. 293 294 t Go to the next tag, if there were more than one matches for the 295 current tag. See the -t option for more details about tags. 296 297 T Go to the previous tag, if there were more than one matches for 298 the current tag. 299 300 = or ^G or :f 301 Prints some information about the file being viewed, including 302 its name and the line number and byte offset of the bottom line 303 being displayed. If possible, it also prints the length of the 304 file, the number of lines in the file and the percent of the 305 file above the last displayed line. 306 307 - Followed by one of the command line option letters (see OPTIONS 308 below), this will change the setting of that option and print a 309 message describing the new setting. If a ^P (CONTROL-P) is 310 entered immediately after the dash, the setting of the option is 311 changed but no message is printed. If the option letter has a 312 numeric value (such as -b or -h), or a string value (such as -P 313 or -t), a new value may be entered after the option letter. If 314 no new value is entered, a message describing the current set- 315 ting is printed and nothing is changed. 316 317 -- Like the - command, but takes a long option name (see OPTIONS 318 below) rather than a single option letter. You must press 319 RETURN after typing the option name. A ^P immediately after the 320 second dash suppresses printing of a message describing the new 321 setting, as in the - command. 322 323 -+ Followed by one of the command line option letters this will 324 reset the option to its default setting and print a message 325 describing the new setting. (The "-+[4mX[24m" command does the same 326 thing as "-+[4mX[24m" on the command line.) This does not work for 327 string-valued options. 328 329 --+ Like the -+ command, but takes a long option name rather than a 330 single option letter. 331 332 -! Followed by one of the command line option letters, this will 333 reset the option to the "opposite" of its default setting and 334 print a message describing the new setting. This does not work 335 for numeric or string-valued options. 336 337 --! Like the -! command, but takes a long option name rather than a 338 single option letter. 339 340 _ (Underscore.) Followed by one of the command line option let- 341 ters, this will print a message describing the current setting 342 of that option. The setting of the option is not changed. 343 344 __ (Double underscore.) Like the _ (underscore) command, but takes 345 a long option name rather than a single option letter. You must 346 press RETURN after typing the option name. 347 348 +cmd Causes the specified cmd to be executed each time a new file is 349 examined. For example, +G causes [4mless[24m to initially display each 350 file starting at the end rather than the beginning. 351 352 V Prints the version number of [4mless[24m being run. 353 354 q or Q or :q or :Q or ZZ 355 Exits [4mless.[0m 356 357 The following four commands may or may not be valid, depending on your 358 particular installation. 359 360 361 v Invokes an editor to edit the current file being viewed. The 362 editor is taken from the environment variable VISUAL if defined, 363 or EDITOR if VISUAL is not defined, or defaults to "vi" if nei- 364 ther VISUAL nor EDITOR is defined. See also the discussion of 365 LESSEDIT under the section on PROMPTS below. 366 367 ! shell-command 368 Invokes a shell to run the shell-command given. A percent sign 369 (%) in the command is replaced by the name of the current file. 370 A pound sign (#) is replaced by the name of the previously exam- 371 ined file. "!!" repeats the last shell command. "!" with no 372 shell command simply invokes a shell. On Unix systems, the 373 shell is taken from the environment variable SHELL, or defaults 374 to "sh". On MS-DOS and OS/2 systems, the shell is the normal 375 command processor. 376 377 | <m> shell-command 378 <m> represents any mark letter. Pipes a section of the input 379 file to the given shell command. The section of the file to be 380 piped is between the first line on the current screen and the 381 position marked by the letter. <m> may also be ^ or $ to indi- 382 cate beginning or end of file respectively. If <m> is . or new- 383 line, the current screen is piped. 384 385 s filename 386 Save the input to a file. This only works if the input is a 387 pipe, not an ordinary file. 388 389 390[1mOPTIONS[0m 391 Command line options are described below. Most options may be changed 392 while [4mless[24m is running, via the "-" command. 393 394 Most options may be given in one of two forms: either a dash followed 395 by a single letter, or two dashes followed by a long option name. A 396 long option name may be abbreviated as long as the abbreviation is 397 unambiguous. For example, --quit-at-eof may be abbreviated --quit, but 398 not --qui, since both --quit-at-eof and --quiet begin with --qui. Some 399 long option names are in uppercase, such as --QUIT-AT-EOF, as distinct 400 from --quit-at-eof. Such option names need only have their first let- 401 ter capitalized; the remainder of the name may be in either case. For 402 example, --Quit-at-eof is equivalent to --QUIT-AT-EOF. 403 404 Options are also taken from the environment variable "LESS". For exam- 405 ple, to avoid typing "less -options ..." each time [4mless[24m is invoked, you 406 might tell [4mcsh:[0m 407 408 setenv LESS "-options" 409 410 or if you use [4msh:[0m 411 412 LESS="-options"; export LESS 413 414 On MS-DOS, you don't need the quotes, but you should replace any per- 415 cent signs in the options string by double percent signs. 416 417 The environment variable is parsed before the command line, so command 418 line options override the LESS environment variable. If an option 419 appears in the LESS variable, it can be reset to its default value on 420 the command line by beginning the command line option with "-+". 421 422 For options like -P or -D which take a following string, a dollar sign 423 ($) must be used to signal the end of the string. For example, to set 424 two -D options on MS-DOS, you must have a dollar sign between them, 425 like this: 426 427 LESS="-Dn9.1$-Ds4.1" 428 429 430 -? or --help 431 This option displays a summary of the commands accepted by [4mless[0m 432 (the same as the h command). (Depending on how your shell 433 interprets the question mark, it may be necessary to quote the 434 question mark, thus: "-\?".) 435 436 -a or --search-skip-screen 437 Causes searches to start after the last line displayed on the 438 screen, thus skipping all lines displayed on the screen. By 439 default, searches start at the second line on the screen (or 440 after the last found line; see the -j option). 441 442 -b[4mn[24m or --buffers=[4mn[0m 443 Specifies the amount of buffer space [4mless[24m will use for each 444 file, in units of kilobytes (1024 bytes). By default 64K of 445 buffer space is used for each file (unless the file is a pipe; 446 see the -B option). The -b option specifies instead that [4mn[0m 447 kilobytes of buffer space should be used for each file. If [4mn[24m is 448 -1, buffer space is unlimited; that is, the entire file can be 449 read into memory. 450 451 -B or --auto-buffers 452 By default, when data is read from a pipe, buffers are allocated 453 automatically as needed. If a large amount of data is read from 454 the pipe, this can cause a large amount of memory to be allo- 455 cated. The -B option disables this automatic allocation of 456 buffers for pipes, so that only 64K (or the amount of space 457 specified by the -b option) is used for the pipe. Warning: use 458 of -B can result in erroneous display, since only the most 459 recently viewed part of the piped data is kept in memory; any 460 earlier data is lost. 461 462 -c or --clear-screen 463 Causes full screen repaints to be painted from the top line 464 down. By default, full screen repaints are done by scrolling 465 from the bottom of the screen. 466 467 -C or --CLEAR-SCREEN 468 Same as -c, for compatibility with older versions of [4mless.[0m 469 470 -d or --dumb 471 The -d option suppresses the error message normally displayed if 472 the terminal is dumb; that is, lacks some important capability, 473 such as the ability to clear the screen or scroll backward. The 474 -d option does not otherwise change the behavior of [4mless[24m on a 475 dumb terminal. 476 477 -D[1mx[4m[22mcolor[24m or --color=[1mx[4m[22mcolor[0m 478 [MS-DOS only] Sets the color of the text displayed. [1mx [22mis a sin- 479 gle character which selects the type of text whose color is 480 being set: n=normal, s=standout, d=bold, u=underlined, k=blink. 481 [4mcolor[24m is a pair of numbers separated by a period. The first 482 number selects the foreground color and the second selects the 483 background color of the text. A single number [4mN[24m is the same as 484 [4mN.0[24m. 485 486 -e or --quit-at-eof 487 Causes [4mless[24m to automatically exit the second time it reaches 488 end-of-file. By default, the only way to exit [4mless[24m is via the 489 "q" command. 490 491 -E or --QUIT-AT-EOF 492 Causes [4mless[24m to automatically exit the first time it reaches end- 493 of-file. 494 495 -f or --force 496 Forces non-regular files to be opened. (A non-regular file is a 497 directory or a device special file.) Also suppresses the warn- 498 ing message when a binary file is opened. By default, [4mless[24m will 499 refuse to open non-regular files. Note that some operating sys- 500 tems will not allow directories to be read, even if -f is set. 501 502 -F or --quit-if-one-screen 503 Causes [4mless[24m to automatically exit if the entire file can be dis- 504 played on the first screen. 505 506 -g or --hilite-search 507 Normally, [4mless[24m will highlight ALL strings which match the last 508 search command. The -g option changes this behavior to high- 509 light only the particular string which was found by the last 510 search command. This can cause [4mless[24m to run somewhat faster than 511 the default. 512 513 -G or --HILITE-SEARCH 514 The -G option suppresses all highlighting of strings found by 515 search commands. 516 517 -h[4mn[24m or --max-back-scroll=[4mn[0m 518 Specifies a maximum number of lines to scroll backward. If it 519 is necessary to scroll backward more than [4mn[24m lines, the screen is 520 repainted in a forward direction instead. (If the terminal does 521 not have the ability to scroll backward, -h0 is implied.) 522 523 -i or --ignore-case 524 Causes searches to ignore case; that is, uppercase and lowercase 525 are considered identical. This option is ignored if any upper- 526 case letters appear in the search pattern; in other words, if a 527 pattern contains uppercase letters, then that search does not 528 ignore case. 529 530 -I or --IGNORE-CASE 531 Like -i, but searches ignore case even if the pattern contains 532 uppercase letters. 533 534 -j[4mn[24m or --jump-target=[4mn[0m 535 Specifies a line on the screen where the "target" line is to be 536 positioned. The target line is the line specified by any com- 537 mand to search for a pattern, jump to a line number, jump to a 538 file percentage or jump to a tag. The screen line may be speci- 539 fied by a number: the top line on the screen is 1, the next is 540 2, and so on. The number may be negative to specify a line rel- 541 ative to the bottom of the screen: the bottom line on the screen 542 is -1, the second to the bottom is -2, and so on. Alternately, 543 the screen line may be specified as a fraction of the height of 544 the screen, starting with a decimal point: .5 is in the middle 545 of the screen, .3 is three tenths down from the first line, and 546 so on. If the line is specified as a fraction, the actual line 547 number is recalculated if the terminal window is resized, so 548 that the target line remains at the specified fraction of the 549 screen height. If any form of the -j option is used, forward 550 searches begin at the line immediately after the target line, 551 and backward searches begin at the target line. For example, if 552 "-j4" is used, the target line is the fourth line on the screen, 553 so forward searches begin at the fifth line on the screen. 554 555 -J or --status-column 556 Displays a status column at the left edge of the screen. The 557 status column shows the lines that matched the current search. 558 The status column is also used if the -w or -W option is in 559 effect. 560 561 -k[4mfilename[24m or --lesskey-file=[4mfilename[0m 562 Causes [4mless[24m to open and interpret the named file as a [4mlesskey[0m 563 (1) file. Multiple -k options may be specified. If the LESSKEY 564 or LESSKEY_SYSTEM environment variable is set, or if a lesskey 565 file is found in a standard place (see KEY BINDINGS), it is also 566 used as a [4mlesskey[24m file. 567 568 -K or --quit-on-intr 569 Causes [4mless[24m to exit immediately when an interrupt character 570 (usually ^C) is typed. Normally, an interrupt character causes 571 [4mless[24m to stop whatever it is doing and return to its command 572 prompt. Note that use of this option makes it impossible to 573 return to the command prompt from the "F" command. 574 575 -L or --no-lessopen 576 Ignore the LESSOPEN environment variable (see the INPUT PREPRO- 577 CESSOR section below). This option can be set from within [4mless[24m, 578 but it will apply only to files opened subsequently, not to the 579 file which is currently open. 580 581 -m or --long-prompt 582 Causes [4mless[24m to prompt verbosely (like [4mmore[24m), with the percent 583 into the file. By default, [4mless[24m prompts with a colon. 584 585 -M or --LONG-PROMPT 586 Causes [4mless[24m to prompt even more verbosely than [4mmore.[0m 587 588 -n or --line-numbers 589 Suppresses line numbers. The default (to use line numbers) may 590 cause [4mless[24m to run more slowly in some cases, especially with a 591 very large input file. Suppressing line numbers with the -n 592 option will avoid this problem. Using line numbers means: the 593 line number will be displayed in the verbose prompt and in the = 594 command, and the v command will pass the current line number to 595 the editor (see also the discussion of LESSEDIT in PROMPTS 596 below). 597 598 -N or --LINE-NUMBERS 599 Causes a line number to be displayed at the beginning of each 600 line in the display. 601 602 -o[4mfilename[24m or --log-file=[4mfilename[0m 603 Causes [4mless[24m to copy its input to the named file as it is being 604 viewed. This applies only when the input file is a pipe, not an 605 ordinary file. If the file already exists, [4mless[24m will ask for 606 confirmation before overwriting it. 607 608 -O[4mfilename[24m or --LOG-FILE=[4mfilename[0m 609 The -O option is like -o, but it will overwrite an existing file 610 without asking for confirmation. 611 612 If no log file has been specified, the -o and -O options can be 613 used from within [4mless[24m to specify a log file. Without a file 614 name, they will simply report the name of the log file. The "s" 615 command is equivalent to specifying -o from within [4mless.[0m 616 617 -p[4mpattern[24m or --pattern=[4mpattern[0m 618 The -p option on the command line is equivalent to specifying 619 +/[4mpattern[24m; that is, it tells [4mless[24m to start at the first occur- 620 rence of [4mpattern[24m in the file. 621 622 -P[4mprompt[24m or --prompt=[4mprompt[0m 623 Provides a way to tailor the three prompt styles to your own 624 preference. This option would normally be put in the LESS envi- 625 ronment variable, rather than being typed in with each [4mless[24m com- 626 mand. Such an option must either be the last option in the LESS 627 variable, or be terminated by a dollar sign. -Ps followed by a 628 string changes the default (short) prompt to that string. -Pm 629 changes the medium (-m) prompt. -PM changes the long (-M) 630 prompt. -Ph changes the prompt for the help screen. -P= 631 changes the message printed by the = command. -Pw changes the 632 message printed while waiting for data (in the F command). All 633 prompt strings consist of a sequence of letters and special 634 escape sequences. See the section on PROMPTS for more details. 635 636 -q or --quiet or --silent 637 Causes moderately "quiet" operation: the terminal bell is not 638 rung if an attempt is made to scroll past the end of the file or 639 before the beginning of the file. If the terminal has a "visual 640 bell", it is used instead. The bell will be rung on certain 641 other errors, such as typing an invalid character. The default 642 is to ring the terminal bell in all such cases. 643 644 -Q or --QUIET or --SILENT 645 Causes totally "quiet" operation: the terminal bell is never 646 rung. 647 648 -r or --raw-control-chars 649 Causes "raw" control characters to be displayed. The default is 650 to display control characters using the caret notation; for 651 example, a control-A (octal 001) is displayed as "^A". Warning: 652 when the -r option is used, [4mless[24m cannot keep track of the actual 653 appearance of the screen (since this depends on how the screen 654 responds to each type of control character). Thus, various dis- 655 play problems may result, such as long lines being split in the 656 wrong place. 657 658 -R or --RAW-CONTROL-CHARS 659 Like -r, but only ANSI "color" escape sequences are output in 660 "raw" form. Unlike -r, the screen appearance is maintained cor- 661 rectly in most cases. ANSI "color" escape sequences are 662 sequences of the form: 663 664 ESC [ ... m 665 666 where the "..." is zero or more color specification characters 667 For the purpose of keeping track of screen appearance, ANSI 668 color escape sequences are assumed to not move the cursor. You 669 can make [4mless[24m think that characters other than "m" can end ANSI 670 color escape sequences by setting the environment variable 671 LESSANSIENDCHARS to the list of characters which can end a color 672 escape sequence. And you can make [4mless[24m think that characters 673 other than the standard ones may appear between the ESC and the 674 m by setting the environment variable LESSANSIMIDCHARS to the 675 list of characters which can appear. 676 677 -s or --squeeze-blank-lines 678 Causes consecutive blank lines to be squeezed into a single 679 blank line. This is useful when viewing [4mnroff[24m output. 680 681 -S or --chop-long-lines 682 Causes lines longer than the screen width to be chopped rather 683 than folded. That is, the portion of a long line that does not 684 fit in the screen width is not shown. The default is to fold 685 long lines; that is, display the remainder on the next line. 686 687 -t[4mtag[24m or --tag=[4mtag[0m 688 The -t option, followed immediately by a TAG, will edit the file 689 containing that tag. For this to work, tag information must be 690 available; for example, there may be a file in the current 691 directory called "tags", which was previously built by [4mctags[24m (1) 692 or an equivalent command. If the environment variable LESSGLOB- 693 ALTAGS is set, it is taken to be the name of a command compati- 694 ble with [4mglobal[24m (1), and that command is executed to find the 695 tag. (See http://www.gnu.org/software/global/global.html). The 696 -t option may also be specified from within [4mless[24m (using the - 697 command) as a way of examining a new file. The command ":t" is 698 equivalent to specifying -t from within [4mless.[0m 699 700 -T[4mtagsfile[24m or --tag-file=[4mtagsfile[0m 701 Specifies a tags file to be used instead of "tags". 702 703 -u or --underline-special 704 Causes backspaces and carriage returns to be treated as print- 705 able characters; that is, they are sent to the terminal when 706 they appear in the input. 707 708 -U or --UNDERLINE-SPECIAL 709 Causes backspaces, tabs and carriage returns to be treated as 710 control characters; that is, they are handled as specified by 711 the -r option. 712 713 By default, if neither -u nor -U is given, backspaces which 714 appear adjacent to an underscore character are treated spe- 715 cially: the underlined text is displayed using the terminal's 716 hardware underlining capability. Also, backspaces which appear 717 between two identical characters are treated specially: the 718 overstruck text is printed using the terminal's hardware bold- 719 face capability. Other backspaces are deleted, along with the 720 preceding character. Carriage returns immediately followed by a 721 newline are deleted. other carriage returns are handled as 722 specified by the -r option. Text which is overstruck or under- 723 lined can be searched for if neither -u nor -U is in effect. 724 725 -V or --version 726 Displays the version number of [4mless.[0m 727 728 -w or --hilite-unread 729 Temporarily highlights the first "new" line after a forward 730 movement of a full page. The first "new" line is the line imme- 731 diately following the line previously at the bottom of the 732 screen. Also highlights the target line after a g or p command. 733 The highlight is removed at the next command which causes move- 734 ment. The entire line is highlighted, unless the -J option is 735 in effect, in which case only the status column is highlighted. 736 737 -W or --HILITE-UNREAD 738 Like -w, but temporarily highlights the first new line after any 739 forward movement command larger than one line. 740 741 -x[4mn[24m,... or --tabs=[4mn[24m,... 742 Sets tab stops. If only one [4mn[24m is specified, tab stops are set 743 at multiples of [4mn[24m. If multiple values separated by commas are 744 specified, tab stops are set at those positions, and then con- 745 tinue with the same spacing as the last two. For example, 746 [4m-x9,17[24m will set tabs at positions 9, 17, 25, 33, etc. The 747 default for [4mn[24m is 8. 748 749 -X or --no-init 750 Disables sending the termcap initialization and deinitialization 751 strings to the terminal. This is sometimes desirable if the 752 deinitialization string does something unnecessary, like clear- 753 ing the screen. 754 755 -y[4mn[24m or --max-forw-scroll=[4mn[0m 756 Specifies a maximum number of lines to scroll forward. If it is 757 necessary to scroll forward more than [4mn[24m lines, the screen is 758 repainted instead. The -c or -C option may be used to repaint 759 from the top of the screen if desired. By default, any forward 760 movement causes scrolling. 761 762 -[z][4mn[24m or --window=[4mn[0m 763 Changes the default scrolling window size to [4mn[24m lines. The 764 default is one screenful. The z and w commands can also be used 765 to change the window size. The "z" may be omitted for compati- 766 bility with some versions of [4mmore.[24m If the number [4mn[24m is negative, 767 it indicates [4mn[24m lines less than the current screen size. For 768 example, if the screen is 24 lines, [4m-z-4[24m sets the scrolling win- 769 dow to 20 lines. If the screen is resized to 40 lines, the 770 scrolling window automatically changes to 36 lines. 771 772 -[4m"cc[24m or --quotes=[4mcc[0m 773 Changes the filename quoting character. This may be necessary 774 if you are trying to name a file which contains both spaces and 775 quote characters. Followed by a single character, this changes 776 the quote character to that character. Filenames containing a 777 space should then be surrounded by that character rather than by 778 double quotes. Followed by two characters, changes the open 779 quote to the first character, and the close quote to the second 780 character. Filenames containing a space should then be preceded 781 by the open quote character and followed by the close quote 782 character. Note that even after the quote characters are 783 changed, this option remains -" (a dash followed by a double 784 quote). 785 786 -~ or --tilde 787 Normally lines after end of file are displayed as a single tilde 788 (~). This option causes lines after end of file to be displayed 789 as blank lines. 790 791 -# or --shift 792 Specifies the default number of positions to scroll horizontally 793 in the RIGHTARROW and LEFTARROW commands. If the number speci- 794 fied is zero, it sets the default number of positions to one 795 half of the screen width. 796 797 --no-keypad 798 Disables sending the keypad initialization and deinitialization 799 strings to the terminal. This is sometimes useful if the keypad 800 strings make the numeric keypad behave in an undesirable manner. 801 802 --follow-name 803 Normally, if the input file is renamed while an F command is 804 executing, [4mless[24m will continue to display the contents of the 805 original file despite its name change. If --follow-name is 806 specified, during an F command [4mless[24m will periodically attempt to 807 reopen the file by name. If the reopen succeeds and the file is 808 a different file from the original (which means that a new file 809 has been created with the same name as the original (now 810 renamed) file), [4mless[24m will display the contents of that new file. 811 812 -- A command line argument of "--" marks the end of option argu- 813 ments. Any arguments following this are interpreted as file- 814 names. This can be useful when viewing a file whose name begins 815 with a "-" or "+". 816 817 + If a command line option begins with [1m+[22m, the remainder of that 818 option is taken to be an initial command to [4mless.[24m For example, 819 +G tells [4mless[24m to start at the end of the file rather than the 820 beginning, and +/xyz tells it to start at the first occurrence 821 of "xyz" in the file. As a special case, +<number> acts like 822 +<number>g; that is, it starts the display at the specified line 823 number (however, see the caveat under the "g" command above). 824 If the option starts with ++, the initial command applies to 825 every file being viewed, not just the first one. The + command 826 described previously may also be used to set (or change) an ini- 827 tial command for every file. 828 829 830[1mLINE EDITING[0m 831 When entering command line at the bottom of the screen (for example, a 832 filename for the :e command, or the pattern for a search command), cer- 833 tain keys can be used to manipulate the command line. Most commands 834 have an alternate form in [ brackets ] which can be used if a key does 835 not exist on a particular keyboard. (The bracketed forms do not work 836 in the MS-DOS version.) Any of these special keys may be entered lit- 837 erally by preceding it with the "literal" character, either ^V or ^A. 838 A backslash itself may also be entered literally by entering two back- 839 slashes. 840 841 LEFTARROW [ ESC-h ] 842 Move the cursor one space to the left. 843 844 RIGHTARROW [ ESC-l ] 845 Move the cursor one space to the right. 846 847 ^LEFTARROW [ ESC-b or ESC-LEFTARROW ] 848 (That is, CONTROL and LEFTARROW simultaneously.) Move the cur- 849 sor one word to the left. 850 851 ^RIGHTARROW [ ESC-w or ESC-RIGHTARROW ] 852 (That is, CONTROL and RIGHTARROW simultaneously.) Move the cur- 853 sor one word to the right. 854 855 HOME [ ESC-0 ] 856 Move the cursor to the beginning of the line. 857 858 END [ ESC-$ ] 859 Move the cursor to the end of the line. 860 861 BACKSPACE 862 Delete the character to the left of the cursor, or cancel the 863 command if the command line is empty. 864 865 DELETE or [ ESC-x ] 866 Delete the character under the cursor. 867 868 ^BACKSPACE [ ESC-BACKSPACE ] 869 (That is, CONTROL and BACKSPACE simultaneously.) Delete the 870 word to the left of the cursor. 871 872 ^DELETE [ ESC-X or ESC-DELETE ] 873 (That is, CONTROL and DELETE simultaneously.) Delete the word 874 under the cursor. 875 876 UPARROW [ ESC-k ] 877 Retrieve the previous command line. 878 879 DOWNARROW [ ESC-j ] 880 Retrieve the next command line. 881 882 TAB Complete the partial filename to the left of the cursor. If it 883 matches more than one filename, the first match is entered into 884 the command line. Repeated TABs will cycle thru the other 885 matching filenames. If the completed filename is a directory, a 886 "/" is appended to the filename. (On MS-DOS systems, a "\" is 887 appended.) The environment variable LESSSEPARATOR can be used 888 to specify a different character to append to a directory name. 889 890 BACKTAB [ ESC-TAB ] 891 Like, TAB, but cycles in the reverse direction thru the matching 892 filenames. 893 894 ^L Complete the partial filename to the left of the cursor. If it 895 matches more than one filename, all matches are entered into the 896 command line (if they fit). 897 898 ^U (Unix and OS/2) or ESC (MS-DOS) 899 Delete the entire command line, or cancel the command if the 900 command line is empty. If you have changed your line-kill char- 901 acter in Unix to something other than ^U, that character is used 902 instead of ^U. 903 904 905[1mKEY BINDINGS[0m 906 You may define your own [4mless[24m commands by using the program [4mlesskey[24m (1) 907 to create a lesskey file. This file specifies a set of command keys 908 and an action associated with each key. You may also use [4mlesskey[24m to 909 change the line-editing keys (see LINE EDITING), and to set environment 910 variables. If the environment variable LESSKEY is set, [4mless[24m uses that 911 as the name of the lesskey file. Otherwise, [4mless[24m looks in a standard 912 place for the lesskey file: On Unix systems, [4mless[24m looks for a lesskey 913 file called "$HOME/.less". On MS-DOS and Windows systems, [4mless[24m looks 914 for a lesskey file called "$HOME/_less", and if it is not found there, 915 then looks for a lesskey file called "_less" in any directory specified 916 in the PATH environment variable. On OS/2 systems, [4mless[24m looks for a 917 lesskey file called "$HOME/less.ini", and if it is not found, then 918 looks for a lesskey file called "less.ini" in any directory specified 919 in the INIT environment variable, and if it not found there, then looks 920 for a lesskey file called "less.ini" in any directory specified in the 921 PATH environment variable. See the [4mlesskey[24m manual page for more 922 details. 923 924 A system-wide lesskey file may also be set up to provide key bindings. 925 If a key is defined in both a local lesskey file and in the system-wide 926 file, key bindings in the local file take precedence over those in the 927 system-wide file. If the environment variable LESSKEY_SYSTEM is set, 928 [4mless[24m uses that as the name of the system-wide lesskey file. Otherwise, 929 [4mless[24m looks in a standard place for the system-wide lesskey file: On 930 Unix systems, the system-wide lesskey file is /usr/local/etc/sysless. 931 (However, if [4mless[24m was built with a different sysconf directory than 932 /usr/local/etc, that directory is where the sysless file is found.) On 933 MS-DOS and Windows systems, the system-wide lesskey file is c:\_sys- 934 less. On OS/2 systems, the system-wide lesskey file is c:\sysless.ini. 935 936 937[1mINPUT PREPROCESSOR[0m 938 You may define an "input preprocessor" for [4mless.[24m Before [4mless[24m opens a 939 file, it first gives your input preprocessor a chance to modify the way 940 the contents of the file are displayed. An input preprocessor is sim- 941 ply an executable program (or shell script), which writes the contents 942 of the file to a different file, called the replacement file. The con- 943 tents of the replacement file are then displayed in place of the con- 944 tents of the original file. However, it will appear to the user as if 945 the original file is opened; that is, [4mless[24m will display the original 946 filename as the name of the current file. 947 948 An input preprocessor receives one command line argument, the original 949 filename, as entered by the user. It should create the replacement 950 file, and when finished, print the name of the replacement file to its 951 standard output. If the input preprocessor does not output a replace- 952 ment filename, [4mless[24m uses the original file, as normal. The input pre- 953 processor is not called when viewing standard input. To set up an 954 input preprocessor, set the LESSOPEN environment variable to a command 955 line which will invoke your input preprocessor. This command line 956 should include one occurrence of the string "%s", which will be 957 replaced by the filename when the input preprocessor command is 958 invoked. 959 960 When [4mless[24m closes a file opened in such a way, it will call another pro- 961 gram, called the input postprocessor, which may perform any desired 962 clean-up action (such as deleting the replacement file created by 963 LESSOPEN). This program receives two command line arguments, the orig- 964 inal filename as entered by the user, and the name of the replacement 965 file. To set up an input postprocessor, set the LESSCLOSE environment 966 variable to a command line which will invoke your input postprocessor. 967 It may include two occurrences of the string "%s"; the first is 968 replaced with the original name of the file and the second with the 969 name of the replacement file, which was output by LESSOPEN. 970 971 For example, on many Unix systems, these two scripts will allow you to 972 keep files in compressed format, but still let [4mless[24m view them directly: 973 974 lessopen.sh: 975 #! /bin/sh 976 case "$1" in 977 *.Z) uncompress - 978 if [ -s /tmp/less.$$ ]; then 979 echo /tmp/less.$$ 980 else 981 rm -f /tmp/less.$$ 982 fi 983 ;; 984 esac 985 986 lessclose.sh: 987 #! /bin/sh 988 rm $2 989 990 To use these scripts, put them both where they can be executed and set 991 LESSOPEN="lessopen.sh %s", and LESSCLOSE="lessclose.sh %s %s". More 992 complex LESSOPEN and LESSCLOSE scripts may be written to accept other 993 types of compressed files, and so on. 994 995 It is also possible to set up an input preprocessor to pipe the file 996 data directly to [4mless,[24m rather than putting the data into a replacement 997 file. This avoids the need to decompress the entire file before start- 998 ing to view it. An input preprocessor that works this way is called an 999 input pipe. An input pipe, instead of writing the name of a replace- 1000 ment file on its standard output, writes the entire contents of the 1001 replacement file on its standard output. If the input pipe does not 1002 write any characters on its standard output, then there is no replace- 1003 ment file and [4mless[24m uses the original file, as normal. To use an input 1004 pipe, make the first character in the LESSOPEN environment variable a 1005 vertical bar (|) to signify that the input preprocessor is an input 1006 pipe. 1007 1008 For example, on many Unix systems, this script will work like the pre- 1009 vious example scripts: 1010 1011 lesspipe.sh: 1012 #! /bin/sh 1013 case "$1" in 1014 *.Z) uncompress -c $1 2>/dev/null 1015 ;; 1016 esac 1017 1018 To use this script, put it where it can be executed and set 1019 LESSOPEN="|lesspipe.sh %s". When an input pipe is used, a LESSCLOSE 1020 postprocessor can be used, but it is usually not necessary since there 1021 is no replacement file to clean up. In this case, the replacement file 1022 name passed to the LESSCLOSE postprocessor is "-". 1023 1024 1025[1mNATIONAL CHARACTER SETS[0m 1026 There are three types of characters in the input file: 1027 1028 normal characters 1029 can be displayed directly to the screen. 1030 1031 control characters 1032 should not be displayed directly, but are expected to be found 1033 in ordinary text files (such as backspace and tab). 1034 1035 binary characters 1036 should not be displayed directly and are not expected to be 1037 found in text files. 1038 1039 A "character set" is simply a description of which characters are to be 1040 considered normal, control, and binary. The LESSCHARSET environment 1041 variable may be used to select a character set. Possible values for 1042 LESSCHARSET are: 1043 1044 ascii BS, TAB, NL, CR, and formfeed are control characters, all chars 1045 with values between 32 and 126 are normal, and all others are 1046 binary. 1047 1048 iso8859 1049 Selects an ISO 8859 character set. This is the same as ASCII, 1050 except characters between 160 and 255 are treated as normal 1051 characters. 1052 1053 latin1 Same as iso8859. 1054 1055 latin9 Same as iso8859. 1056 1057 dos Selects a character set appropriate for MS-DOS. 1058 1059 ebcdic Selects an EBCDIC character set. 1060 1061 IBM-1047 1062 Selects an EBCDIC character set used by OS/390 Unix Services. 1063 This is the EBCDIC analogue of latin1. You get similar results 1064 by setting either LESSCHARSET=IBM-1047 or LC_CTYPE=en_US in your 1065 environment. 1066 1067 koi8-r Selects a Russian character set. 1068 1069 next Selects a character set appropriate for NeXT computers. 1070 1071 utf-8 Selects the UTF-8 encoding of the ISO 10646 character set. 1072 UTF-8 is special in that it supports multi-byte characters in 1073 the input file. It is the only character set that supports 1074 multi-byte characters. 1075 1076 windows 1077 Selects a character set appropriate for Microsoft Windows (cp 1078 1251). 1079 1080 In special cases, it may be desired to tailor [4mless[24m to use a character 1081 set other than the ones definable by LESSCHARSET. In this case, the 1082 environment variable LESSCHARDEF can be used to define a character set. 1083 It should be set to a string where each character in the string repre- 1084 sents one character in the character set. The character "." is used 1085 for a normal character, "c" for control, and "b" for binary. A decimal 1086 number may be used for repetition. For example, "bccc4b." would mean 1087 character 0 is binary, 1, 2 and 3 are control, 4, 5, 6 and 7 are 1088 binary, and 8 is normal. All characters after the last are taken to be 1089 the same as the last, so characters 9 through 255 would be normal. 1090 (This is an example, and does not necessarily represent any real char- 1091 acter set.) 1092 1093 This table shows the value of LESSCHARDEF which is equivalent to each 1094 of the possible values for LESSCHARSET: 1095 1096 ascii 8bcccbcc18b95.b 1097 dos 8bcccbcc12bc5b95.b. 1098 ebcdic 5bc6bcc7bcc41b.9b7.9b5.b..8b6.10b6.b9.7b 1099 9.8b8.17b3.3b9.7b9.8b8.6b10.b.b.b. 1100 IBM-1047 4cbcbc3b9cbccbccbb4c6bcc5b3cbbc4bc4bccbc 1101 191.b 1102 iso8859 8bcccbcc18b95.33b. 1103 koi8-r 8bcccbcc18b95.b128. 1104 latin1 8bcccbcc18b95.33b. 1105 next 8bcccbcc18b95.bb125.bb 1106 1107 If neither LESSCHARSET nor LESSCHARDEF is set, but any of the strings 1108 "UTF-8", "UTF8", "utf-8" or "utf8" is found in the LC_ALL, LC_TYPE or 1109 LANG environment variables, then the default character set is utf-8. 1110 1111 If that string is not found, but your system supports the [4msetlocale[0m 1112 interface, [4mless[24m will use setlocale to determine the character set. 1113 setlocale is controlled by setting the LANG or LC_CTYPE environment 1114 variables. 1115 1116 Finally, if the [4msetlocale[24m interface is also not available, the default 1117 character set is latin1. 1118 1119 Control and binary characters are displayed in standout (reverse 1120 video). Each such character is displayed in caret notation if possible 1121 (e.g. ^A for control-A). Caret notation is used only if inverting the 1122 0100 bit results in a normal printable character. Otherwise, the char- 1123 acter is displayed as a hex number in angle brackets. This format can 1124 be changed by setting the LESSBINFMT environment variable. LESSBINFMT 1125 may begin with a "*" and one character to select the display attribute: 1126 "*k" is blinking, "*d" is bold, "*u" is underlined, "*s" is standout, 1127 and "*n" is normal. If LESSBINFMT does not begin with a "*", normal 1128 attribute is assumed. The remainder of LESSBINFMT is a string which 1129 may include one printf-style escape sequence (a % followed by x, X, o, 1130 d, etc.). For example, if LESSBINFMT is "*u[%x]", binary characters 1131 are displayed in underlined hexadecimal surrounded by brackets. The 1132 default if no LESSBINFMT is specified is "*s<%X>". The default if no 1133 LESSBINFMT is specified is "*s<%02X>". Warning: the result of expand- 1134 ing the character via LESSBINFMT must be less than 31 characters. 1135 1136 When the character set is utf-8, the LESSUTFBINFMT environment variable 1137 acts similarly to LESSBINFMT but it applies to Unicode code points that 1138 were successfully decoded but are unsuitable for display (e.g., unas- 1139 signed code points). Its default value is "<U+%04lX>". Note that 1140 LESSUTFBINFMT and LESSBINFMT share their display attribute setting 1141 ("*x") so specifying one will affect both; LESSUTFBINFMT is read after 1142 LESSBINFMT so its setting, if any, will have priority. Problematic 1143 octets in a UTF-8 file (octets of a truncated sequence, octets of a 1144 complete but non-shortest form sequence, illegal octets, and stray 1145 trailing octets) are displayed individually using LESSBINFMT so as to 1146 facilitate diagnostic of how the UTF-8 file is ill-formed. 1147 1148 1149[1mPROMPTS[0m 1150 The -P option allows you to tailor the prompt to your preference. The 1151 string given to the -P option replaces the specified prompt string. 1152 Certain characters in the string are interpreted specially. The prompt 1153 mechanism is rather complicated to provide flexibility, but the ordi- 1154 nary user need not understand the details of constructing personalized 1155 prompt strings. 1156 1157 A percent sign followed by a single character is expanded according to 1158 what the following character is: 1159 1160 %b[4mX[24m Replaced by the byte offset into the current input file. The b 1161 is followed by a single character (shown as [4mX[24m above) which spec- 1162 ifies the line whose byte offset is to be used. If the charac- 1163 ter is a "t", the byte offset of the top line in the display is 1164 used, an "m" means use the middle line, a "b" means use the bot- 1165 tom line, a "B" means use the line just after the bottom line, 1166 and a "j" means use the "target" line, as specified by the -j 1167 option. 1168 1169 %B Replaced by the size of the current input file. 1170 1171 %c Replaced by the column number of the text appearing in the first 1172 column of the screen. 1173 1174 %d[4mX[24m Replaced by the page number of a line in the input file. The 1175 line to be used is determined by the [4mX[24m, as with the %b option. 1176 1177 %D Replaced by the number of pages in the input file, or equiva- 1178 lently, the page number of the last line in the input file. 1179 1180 %E Replaced by the name of the editor (from the VISUAL environment 1181 variable, or the EDITOR environment variable if VISUAL is not 1182 defined). See the discussion of the LESSEDIT feature below. 1183 1184 %f Replaced by the name of the current input file. 1185 1186 %i Replaced by the index of the current file in the list of input 1187 files. 1188 1189 %l[4mX[24m Replaced by the line number of a line in the input file. The 1190 line to be used is determined by the [4mX[24m, as with the %b option. 1191 1192 %L Replaced by the line number of the last line in the input file. 1193 1194 %m Replaced by the total number of input files. 1195 1196 %p[4mX[24m Replaced by the percent into the current input file, based on 1197 byte offsets. The line used is determined by the [4mX[24m as with the 1198 %b option. 1199 1200 %P[4mX[24m Replaced by the percent into the current input file, based on 1201 line numbers. The line used is determined by the [4mX[24m as with the 1202 %b option. 1203 1204 %s Same as %B. 1205 1206 %t Causes any trailing spaces to be removed. Usually used at the 1207 end of the string, but may appear anywhere. 1208 1209 %x Replaced by the name of the next input file in the list. 1210 1211 If any item is unknown (for example, the file size if input is a pipe), 1212 a question mark is printed instead. 1213 1214 The format of the prompt string can be changed depending on certain 1215 conditions. A question mark followed by a single character acts like 1216 an "IF": depending on the following character, a condition is evalu- 1217 ated. If the condition is true, any characters following the question 1218 mark and condition character, up to a period, are included in the 1219 prompt. If the condition is false, such characters are not included. 1220 A colon appearing between the question mark and the period can be used 1221 to establish an "ELSE": any characters between the colon and the period 1222 are included in the string if and only if the IF condition is false. 1223 Condition characters (which follow a question mark) may be: 1224 1225 ?a True if any characters have been included in the prompt so far. 1226 1227 ?b[4mX[24m True if the byte offset of the specified line is known. 1228 1229 ?B True if the size of current input file is known. 1230 1231 ?c True if the text is horizontally shifted (%c is not zero). 1232 1233 ?d[4mX[24m True if the page number of the specified line is known. 1234 1235 ?e True if at end-of-file. 1236 1237 ?f True if there is an input filename (that is, if input is not a 1238 pipe). 1239 1240 ?l[4mX[24m True if the line number of the specified line is known. 1241 1242 ?L True if the line number of the last line in the file is known. 1243 1244 ?m True if there is more than one input file. 1245 1246 ?n True if this is the first prompt in a new input file. 1247 1248 ?p[4mX[24m True if the percent into the current input file, based on byte 1249 offsets, of the specified line is known. 1250 1251 ?P[4mX[24m True if the percent into the current input file, based on line 1252 numbers, of the specified line is known. 1253 1254 ?s Same as "?B". 1255 1256 ?x True if there is a next input file (that is, if the current 1257 input file is not the last one). 1258 1259 Any characters other than the special ones (question mark, colon, 1260 period, percent, and backslash) become literally part of the prompt. 1261 Any of the special characters may be included in the prompt literally 1262 by preceding it with a backslash. 1263 1264 Some examples: 1265 1266 ?f%f:Standard input. 1267 1268 This prompt prints the filename, if known; otherwise the string "Stan- 1269 dard input". 1270 1271 ?f%f .?ltLine %lt:?pt%pt\%:?btByte %bt:-... 1272 1273 This prompt would print the filename, if known. The filename is fol- 1274 lowed by the line number, if known, otherwise the percent if known, 1275 otherwise the byte offset if known. Otherwise, a dash is printed. 1276 Notice how each question mark has a matching period, and how the % 1277 after the %pt is included literally by escaping it with a backslash. 1278 1279 ?n?f%f .?m(file %i of %m) ..?e(END) ?x- Next\: %x..%t 1280 1281 This prints the filename if this is the first prompt in a file, fol- 1282 lowed by the "file N of N" message if there is more than one input 1283 file. Then, if we are at end-of-file, the string "(END)" is printed 1284 followed by the name of the next file, if there is one. Finally, any 1285 trailing spaces are truncated. This is the default prompt. For refer- 1286 ence, here are the defaults for the other two prompts (-m and -M 1287 respectively). Each is broken into two lines here for readability 1288 only. 1289 1290 ?n?f%f .?m(file %i of %m) ..?e(END) ?x- Next\: %x.: 1291 ?pB%pB\%:byte %bB?s/%s...%t 1292 1293 ?f%f .?n?m(file %i of %m) ..?ltlines %lt-%lb?L/%L. : 1294 byte %bB?s/%s. .?e(END) ?x- Next\: %x.:?pB%pB\%..%t 1295 1296 And here is the default message produced by the = command: 1297 1298 ?f%f .?m(file %i of %m) .?ltlines %lt-%lb?L/%L. . 1299 byte %bB?s/%s. ?e(END) :?pB%pB\%..%t 1300 1301 The prompt expansion features are also used for another purpose: if an 1302 environment variable LESSEDIT is defined, it is used as the command to 1303 be executed when the v command is invoked. The LESSEDIT string is 1304 expanded in the same way as the prompt strings. The default value for 1305 LESSEDIT is: 1306 1307 %E ?lm+%lm. %f 1308 1309 Note that this expands to the editor name, followed by a + and the line 1310 number, followed by the file name. If your editor does not accept the 1311 "+linenumber" syntax, or has other differences in invocation syntax, 1312 the LESSEDIT variable can be changed to modify this default. 1313 1314 1315[1mSECURITY[0m 1316 When the environment variable LESSSECURE is set to 1, [4mless[24m runs in a 1317 "secure" mode. This means these features are disabled: 1318 1319 ! the shell command 1320 1321 | the pipe command 1322 1323 :e the examine command. 1324 1325 v the editing command 1326 1327 s -o log files 1328 1329 -k use of lesskey files 1330 1331 -t use of tags files 1332 1333 metacharacters in filenames, such as * 1334 1335 filename completion (TAB, ^L) 1336 1337 Less can also be compiled to be permanently in "secure" mode. 1338 1339 1340[1mCOMPATIBILITY WITH MORE[0m 1341 If the environment variable LESS_IS_MORE is set to 1, or if the program 1342 is invoked via a file link named "more", [4mless[24m behaves (mostly) in con- 1343 formance with the POSIX "more" command specification. In this mode, 1344 less behaves differently in these ways: 1345 1346 The -e option works differently. If the -e option is not set, [4mless[0m 1347 behaves as if the -E option were set. If the -e option is set, [4mless[0m 1348 behaves as if the -e and -F options were set. 1349 1350 The -m option works differently. If the -m option is not set, the 1351 medium prompt is used, and it is prefixed with the string "--More--". 1352 If the -m option is set, the short prompt is used. 1353 1354 The -n option acts like the -z option. The normal behavior of the -n 1355 option is unavailable in this mode. 1356 1357 The parameter to the -p option is taken to be a [4mless[24m command rather 1358 than a search pattern. 1359 1360 The LESS environment variable is ignored, and the MORE environment 1361 variable is used in its place. 1362 1363 1364[1mENVIRONMENT VARIABLES[0m 1365 Environment variables may be specified either in the system environment 1366 as usual, or in a [4mlesskey[24m (1) file. If environment variables are 1367 defined in more than one place, variables defined in a local lesskey 1368 file take precedence over variables defined in the system environment, 1369 which take precedence over variables defined in the system-wide lesskey 1370 file. 1371 1372 COLUMNS 1373 Sets the number of columns on the screen. Takes precedence over 1374 the number of columns specified by the TERM variable. (But if 1375 you have a windowing system which supports TIOCGWINSZ or 1376 WIOCGETD, the window system's idea of the screen size takes 1377 precedence over the LINES and COLUMNS environment variables.) 1378 1379 EDITOR The name of the editor (used for the v command). 1380 1381 HOME Name of the user's home directory (used to find a lesskey file 1382 on Unix and OS/2 systems). 1383 1384 HOMEDRIVE, HOMEPATH 1385 Concatenation of the HOMEDRIVE and HOMEPATH environment vari- 1386 ables is the name of the user's home directory if the HOME vari- 1387 able is not set (only in the Windows version). 1388 1389 INIT Name of the user's init directory (used to find a lesskey file 1390 on OS/2 systems). 1391 1392 LANG Language for determining the character set. 1393 1394 LC_CTYPE 1395 Language for determining the character set. 1396 1397 LESS Options which are passed to [4mless[24m automatically. 1398 1399 LESSANSIENDCHARS 1400 Characters which may end an ANSI color escape sequence (default 1401 "m"). 1402 1403 LESSANSIMIDCHARS 1404 Characters which may appear between the ESC character and the 1405 end character in an ANSI color escape sequence (default 1406 "0123456789;[?!"'#%()*+ ". 1407 1408 LESSBINFMT 1409 Format for displaying non-printable, non-control characters. 1410 1411 LESSCHARDEF 1412 Defines a character set. 1413 1414 LESSCHARSET 1415 Selects a predefined character set. 1416 1417 LESSCLOSE 1418 Command line to invoke the (optional) input-postprocessor. 1419 1420 LESSECHO 1421 Name of the lessecho program (default "lessecho"). The lessecho 1422 program is needed to expand metacharacters, such as * and ?, in 1423 filenames on Unix systems. 1424 1425 LESSEDIT 1426 Editor prototype string (used for the v command). See discus- 1427 sion under PROMPTS. 1428 1429 LESSGLOBALTAGS 1430 Name of the command used by the -t option to find global tags. 1431 Normally should be set to "global" if your system has the [4mglobal[0m 1432 (1) command. If not set, global tags are not used. 1433 1434 LESSHISTFILE 1435 Name of the history file used to remember search commands and 1436 shell commands between invocations of [4mless.[24m If set to "-" or 1437 "/dev/null", a history file is not used. The default is 1438 "$HOME/.lesshst" on Unix systems, "$HOME/_lesshst" on DOS and 1439 Windows systems, or "$HOME/lesshst.ini" or "$INIT/lesshst.ini" 1440 on OS/2 systems. 1441 1442 LESSHISTSIZE 1443 The maximum number of commands to save in the history file. The 1444 default is 100. 1445 1446 LESSKEY 1447 Name of the default lesskey(1) file. 1448 1449 LESSKEY_SYSTEM 1450 Name of the default system-wide lesskey(1) file. 1451 1452 LESSMETACHARS 1453 List of characters which are considered "metacharacters" by the 1454 shell. 1455 1456 LESSMETAESCAPE 1457 Prefix which less will add before each metacharacter in a com- 1458 mand sent to the shell. If LESSMETAESCAPE is an empty string, 1459 commands containing metacharacters will not be passed to the 1460 shell. 1461 1462 LESSOPEN 1463 Command line to invoke the (optional) input-preprocessor. 1464 1465 LESSSECURE 1466 Runs less in "secure" mode. See discussion under SECURITY. 1467 1468 LESSSEPARATOR 1469 String to be appended to a directory name in filename comple- 1470 tion. 1471 1472 LESSUTFBINFMT 1473 Format for displaying non-printable Unicode code points. 1474 1475 LESS_IS_MORE 1476 Emulate the [4mmore[24m (1) command. 1477 1478 LINES Sets the number of lines on the screen. Takes precedence over 1479 the number of lines specified by the TERM variable. (But if you 1480 have a windowing system which supports TIOCGWINSZ or WIOCGETD, 1481 the window system's idea of the screen size takes precedence 1482 over the LINES and COLUMNS environment variables.) 1483 1484 PATH User's search path (used to find a lesskey file on MS-DOS and 1485 OS/2 systems). 1486 1487 SHELL The shell used to execute the ! command, as well as to expand 1488 filenames. 1489 1490 TERM The type of terminal on which [4mless[24m is being run. 1491 1492 VISUAL The name of the editor (used for the v command). 1493 1494 1495[1mSEE ALSO[0m 1496 lesskey(1) 1497 1498 1499[1mWARNINGS[0m 1500 The = command and prompts (unless changed by -P) report the line num- 1501 bers of the lines at the top and bottom of the screen, but the byte and 1502 percent of the line after the one at the bottom of the screen. 1503 1504 On certain older terminals (the so-called "magic cookie" terminals), 1505 search highlighting will cause an erroneous display. On such termi- 1506 nals, search highlighting is disabled by default to avoid possible 1507 problems. 1508 1509 When searching in a binary file, text which follows a null byte may not 1510 be found. This problem does not occur when searching with regular 1511 expressions turned off via ^R, and also does not occur when [4mless[24m is 1512 compiled to use the PCRE regular expression library. 1513 1514 In certain cases, when search highlighting is enabled and a search pat- 1515 tern begins with a ^, more text than the matching string may be high- 1516 lighted. (This problem does not occur when less is compiled to use the 1517 POSIX regular expression package.) 1518 1519 On some systems, [4msetlocale[24m claims that ASCII characters 0 thru 31 are 1520 control characters rather than binary characters. This causes [4mless[24m to 1521 treat some binary files as ordinary, non-binary files. To workaround 1522 this problem, set the environment variable LESSCHARSET to "ascii" (or 1523 whatever character set is appropriate). 1524 1525 This manual is too long. 1526 1527 See http://www.greenwoodsoftware.com/less for the latest list of known 1528 bugs in less. 1529 1530 1531[1mCOPYRIGHT[0m 1532 Copyright (C) 1984-2007 Mark Nudelman 1533 1534 less is part of the GNU project and is free software. You can redis- 1535 tribute it and/or modify it under the terms of either (1) the GNU Gen- 1536 eral Public License as published by the Free Software Foundation; or 1537 (2) the Less License. See the file README in the less distribution for 1538 more details regarding redistribution. You should have received a copy 1539 of the GNU General Public License along with the source for less; see 1540 the file COPYING. If not, write to the Free Software Foundation, 59 1541 Temple Place, Suite 330, Boston, MA 02111-1307, USA. You should also 1542 have received a copy of the Less License; see the file LICENSE. 1543 1544 less is distributed in the hope that it will be useful, but WITHOUT ANY 1545 WARRANTY; without even the implied warranty of MERCHANTABILITY or FIT- 1546 NESS FOR A PARTICULAR PURPOSE. See the GNU General Public License for 1547 more details. 1548 1549 1550[1mAUTHOR[0m 1551 Mark Nudelman <markn@greenwoodsoftware.com> 1552 Send bug reports or comments to the above address or to 1553 bug-less@gnu.org. 1554 For more information, see the less homepage at 1555 http://www.greenwoodsoftware.com/less. 1556 1557 1558 1559 Version 416: 22 Nov 2007 LESS(1) 1560