Knowledge

less (Unix)

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other hand, unlimited buffering means that less will request as much memory as it is fed data, which could drive the system into using virtual memory and swapping a lot of data between RAM and disks (dramatically slowing system performance for most applications on the host), or even further into memory exhaustion where any application on the host requesting memory may have that request denied, or may crash when attempting to access memory that the OS promised but can't find when the application actually attempts to use it and a page-fault occurs. For this reason, some companies/organisations insist that less be used only with fixed buffering - or not at all - on production machines.
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options control how much memory less may use to buffer inputs. This is most relevant when less is directly accessing a named file that is modified or deleted while less is still running, and when less is receiving data from a pipe and the data can not be randomly accessed or regenerated. On the
387:, and automatically determines which program to launch display the file's information with, such as text from a PDF file, metadata of photos, lists of files in a compressed archive, and content of a single file in a compressed archive. 329:
can be invoked with options to change its behaviour, for example, the number of lines to display on the screen. A few options vary depending on the operating system. While
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is displaying the file, various commands can be used to navigate through the file. These commands are based on those used by both
1110: 437:: Set tabstops (the number of columns per hard tab character) to the specified number (3, in this example) (useful for viewing 259:
able to do backward scrolling of the displayed text. The name came from the joke of doing "backwards more." Originally,
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does not need to read the entire file before starting, allowing for immediate viewing regardless of file size.
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was developed for Unix, but it has been ported to a number of other operating systems, including
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The "lesspipe" extension can automatically determine file types such as
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Follow Mode (for expanding logs or pipes). Interrupt (or from v581
465:: Follow mode, for log files that get replaced while being viewed. 1418: 1342: 1083: 1403: 1145: 391: 264: 107: 916:# Case insensitive search for "void" in all .c files 1636: 1533: 1513: 1443: 1362: 1265: 1240: 1215: 1165: 1160: 1155: 1150: 284: 35: 1687: 1661: 1597: 1518: 1413: 1398: 1357: 1347: 1291: 1119: 704: 276: 272: 213: 409:: Highlight just the current match of any searched string. 1488: 1388: 1332: 1230: 380: 1021:"lesspipe(1) — less — Debian bullseye — Debian Manpages" 362:). If the output is redirected to anything other than a 224:
systems used to view (but not change) the contents of a
1210: 26: 421:: Show more detailed prompt, including file position. 358:(usually the output of another command through a 1762: 453:: Leave file contents on screen when less exits. 1104: 287:. It is still maintained today by Nudelman. 253:during 1983–85, in the need of a version of 469: 1743: 1111: 1097: 400: 25: 772:toggles option to match case in searches 366:, for example a pipe to another command, 350:displays the contents of the file to the 921: 427:: Show line numbers (useful for viewing 290:To help remember the difference between 228:one screen at a time. It is similar to 1763: 1092: 13: 1051:. Greenwood Software. 7 April 2021 14: 1787: 1067: 1035:"lesspipe(1) — Arch manual pages" 740:Turn off Match Highlighting (see 1742: 1721: 1720: 1084:Entry in Free Software Directory 306:has greater functionality than 1041: 1027: 1013: 999: 985: 967: 1: 960: 900:# Read "readme.txt" 868:Help. This is presented with 415:: Search case-insensitively. 310:. A similar saying is that " 298:, a common joke is to say, " 7: 938: 892: 667:. Text is interpreted as a 473: 58:; 40 years ago 10: 1792: 1074:Manual page on freebsd.org 241: 81:661 / 30 June 2024 1716: 1670: 1622: 1606: 1585: 1542: 1381: 1325: 1274: 1133: 178: 154: 142: 130: 120: 100: 96: 74: 70: 52: 42: 24: 896: 470:Frequently used commands 321: 1079:Manual page on man7.org 902:less+F/var/log/mail.log 401:Frequently used options 1736:Unix SUS2008 utilities 1731:Standard Unix programs 1123:command-line interface 912:# Easier file analysis 727:Previous Search Match 83:; 2 months ago 922:Memory considerations 904:# Follow mode for log 744:command line option) 686:Backward Search like 1771:GNU Project software 1624:Software development 981:on February 7, 2023. 699:⟨text⟩ 681:⟨text⟩ 664:⟨text⟩ 656:⟨text⟩ 975:"less, a paginator" 661:Forward Search for 520:Previous half Page 385:compressed archives 21: 1049:"Less version 581" 717:Next Search Match 383:, multimedia, and 186:.greenwoodsoftware 19: 1758: 1757: 890: 889: 832:File information 810:⟨c⟩ 802:⟨c⟩ 790:⟨c⟩ 782:⟨c⟩ 762:⟨c⟩ 754:⟨c⟩ 644:⟨n⟩ 633:⟨n⟩ 318:, more or less". 302:," implying that 269:Microsoft Windows 198: 197: 1783: 1746: 1745: 1724: 1723: 1326:User environment 1113: 1106: 1099: 1090: 1089: 1061: 1060: 1058: 1056: 1045: 1039: 1038: 1031: 1025: 1024: 1017: 1011: 1010: 1003: 997: 996: 993:"less home page" 989: 983: 982: 977:. Archived from 971: 933: 929: 917: 913: 909: 905: 901: 898:less-Mreadme.txt 871: 822: 812: 811: 804: 803: 792: 791: 784: 783: 764: 763: 756: 755: 743: 701: 700: 683: 682: 666: 665: 658: 657: 646: 645: 635: 634: 620: 604: 540: 474: 464: 458: 452: 446: 436: 426: 420: 414: 408: 375: 369: 349: 342: 336: 332: 328: 317: 313: 309: 305: 301: 297: 293: 283:systems such as 262: 258: 252: 249:initially wrote 237: 233: 203: 194: 191: 189: 187: 185: 132:Operating system 116: 113: 111: 109: 91: 89: 84: 66: 64: 59: 33: 29: 22: 18: 1791: 1790: 1786: 1785: 1784: 1782: 1781: 1780: 1776:Terminal pagers 1761: 1760: 1759: 1754: 1712: 1666: 1618: 1602: 1581: 1538: 1382:Text processing 1377: 1321: 1270: 1129: 1117: 1070: 1065: 1064: 1054: 1052: 1047: 1046: 1042: 1033: 1032: 1028: 1019: 1018: 1014: 1005: 1004: 1000: 991: 990: 986: 973: 972: 968: 963: 941: 931: 927: 924: 919: 918: 915: 914:less-I-pvoid*.c 911: 907: 903: 899: 895: 883: 875: 869: 865: 855: 852: 842: 839: 829: 825: 820: 819: 809: 808: 801: 800: 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766: 759:Toggle option 757: 749: 746: 745: 738: 735: 732: 729: 728: 725: 722: 719: 718: 715: 712: 709: 708: 702: 694: 691: 690: 687: 684: 676: 673: 672: 659: 651: 648: 647: 639: 636: 628: 627: 624: 621: 615: 612: 611: 608: 605: 599: 596: 595: 591: 587: 584: 581: 578: 577: 574: 571: 568: 567: 564: 561: 558: 557: 556:Previous Line 554: 551: 548: 547: 544: 541: 535: 532: 531: 528: 525: 522: 521: 518: 515: 512: 511: 510:Previous Page 508: 505: 502: 501: 498: 495: 492: 491: 488: 485: 482: 481: 478: 471: 468: 467: 466: 460: 454: 448: 442: 432: 422: 416: 410: 402: 399: 396: 356:standard input 323: 320: 300:less > more 243: 240: 207:terminal pager 196: 195: 180: 176: 175: 158: 152: 151: 149:System utility 146: 140: 139: 137:Cross-platform 134: 128: 127: 122: 118: 117: 104: 98: 97: 94: 93: 80: 78: 76:Stable release 72: 71: 68: 67: 54: 50: 49: 46: 40: 39: 30: 16:Terminal pager 15: 9: 6: 4: 3: 2: 1788: 1777: 1774: 1772: 1769: 1768: 1766: 1751: 1750: 1741: 1737: 1734: 1732: 1729: 1728: 1727: 1719: 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Retrieved 1043: 1029: 1015: 1001: 987: 979:the original 969: 925: 707:like filter 594:) to abort. 576:End of file 566:Top of file 459:: Show help. 390:The command- 389: 378: 346:By default, 345: 325: 289: 245: 200: 199: 44:Developer(s) 1134:File system 950:most (Unix) 928:--buffers=n 807:Go to Mark 610:First Line 439:source code 429:source code 1765:Categories 1726:Categories 1007:"Less FAQ" 961:References 845:Next file 626:Last Line 546:Next Line 490:Next Page 397:less ... 121:Written in 102:Repository 88:2024-06-30 36:x-terminal 1586:Searching 1275:Processes 955:pg (Unix) 876:to quit. 787:Set Mark 486:Space bar 281:Unix-like 226:text file 222:Unix-like 172:BSD-style 1394:basename 939:See also 893:Examples 765:, e.g., 480:Command 364:terminal 1499:strings 1419:dirname 1343:logname 1292:crontab 1055:31 July 542:↵ Enter 242:History 218:Windows 210:program 179:Website 174:license 156:License 86: ( 61: ( 1479:printf 1404:csplit 1146:chattr 392:syntax 275:, and 265:MS-DOS 220:, and 163:under 108:github 1703:sleep 1657:strip 1637:ctags 1572:unset 1552:alias 1534:xargs 1514:troff 1474:patch 1469:paste 1444:iconv 1373:write 1363:uname 1266:umask 1256:touch 1246:split 1241:rmdir 1216:mkdir 1201:fuser 1166:cksum 1161:chgrp 1156:chown 1151:chmod 906:file* 886:Quit 851:: 838:: 695:& 669:regex 641:Line 322:Usage 285:Linux 205:is a 190:/less 168:GPLv3 114:/less 112:/gwsw 1749:List 1688:expr 1662:yacc 1647:make 1598:grep 1593:find 1577:wait 1567:test 1562:echo 1519:uniq 1504:tail 1494:sort 1484:read 1459:more 1449:join 1439:head 1434:fold 1414:diff 1399:comm 1358:tput 1353:talk 1348:mesg 1338:exit 1317:time 1307:nice 1302:kill 1261:type 1196:file 1120:Unix 1057:2023 930:and 926:The 910:less 870:less 824:Ctrl 705:grep 622:> 606:< 588:Ctrl 562:Home 477:Key 394:is: 368:less 360:pipe 348:less 337:and 335:more 331:less 327:less 316:more 312:less 308:more 304:less 296:more 294:and 292:less 277:OS-9 273:OS/2 261:less 256:more 251:less 236:less 231:more 214:Unix 202:less 188:.com 144:Type 110:.com 63:1984 56:1984 32:less 20:less 1683:cal 1642:lex 1614:man 1489:sed 1409:cut 1389:awk 1368:who 1333:env 1251:tee 1231:pwd 1226:pax 1171:cmp 1141:cat 733:Esc 572:End 435:-x3 381:PDF 373:cat 314:is 212:on 184:www 165:GNU 1767:: 1698:od 1693:lp 1678:bc 1652:nm 1632:ar 1557:cd 1529:wc 1524:vi 1509:tr 1464:nl 1454:m4 1429:ex 1424:ed 1312:ps 1297:fg 1287:bg 1282:at 1236:rm 1221:mv 1211:ls 1206:ln 1191:df 1186:du 1181:dd 1176:cp 872:, 821:or 742:-g 671:. 619:or 603:or 539:or 457:-? 451:-X 445:-S 441:). 431:). 425:-N 419:-m 413:-i 407:-g 376:. 340:vi 271:, 267:, 216:, 1112:e 1105:t 1098:v 1059:. 1037:. 1023:. 1009:. 995:. 908:| 882:q 874:q 864:h 854:p 841:n 828:G 826:+ 818:= 798:' 778:m 770:i 767:- 750:- 736:u 723:N 713:n 688:/ 677:? 652:/ 637:G 616:G 600:g 592:X 590:+ 582:F 552:k 536:j 526:v 516:u 506:b 496:d 192:/ 125:C 90:) 65:)

Index


x-terminal
Developer(s)
Stable release
Repository
github.com/gwsw/less
C
Operating system
Cross-platform
Type
System utility
License
Dual-licensed
GNU
GPLv3
BSD-style
www.greenwoodsoftware.com/less/
terminal pager
program
Unix
Windows
Unix-like
text file
more
Mark Nudelman
more
MS-DOS
Microsoft Windows
OS/2
OS-9

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