home *** CD-ROM | disk | FTP | other *** search
/ Usenet 1994 January / usenetsourcesnewsgroupsinfomagicjanuary1994.iso / sources / std_unix / v21 / 091 < prev    next >
Mailbox/MIME Entity  |  1990-12-05  |  7.5 KB

open in: MacOS 8.1     |     Win98     |     DOS

browse contents    |     view JSON data     |     view as text


This file was processed as: Mailbox/MIME Entity (archive/mbox).

ConfidenceProgramDetectionMatch TypeSupport
100% dexvert Mailbox/MIME Entity (archive/mbox) magic Supported
100% dexvert Internet Message Format (text/imf) magic Supported
1% dexvert Text File (text/txt) fallback Supported
100% file Mailbox text, 1st line "From std-unix-request@uunet.uu.net Sat Sep 8 09:21:20 1990", ASCII text default
100% TrID E-Mail message (Var. 2) default
100% checkBytes Printable ASCII default
100% perlTextCheck Likely Text (Perl) default
100% siegfried x-fmt/111 Plain Text File default
100% detectItEasy Format: plain text[LF] default (weak)
100% xdgMime application/mbox default



hex view
+--------+-------------------------+-------------------------+--------+--------+
|00000000| 46 72 6f 6d 20 73 74 64 | 2d 75 6e 69 78 2d 72 65 |From std|-unix-re|
|00000010| 71 75 65 73 74 40 75 75 | 6e 65 74 2e 75 75 2e 6e |quest@uu|net.uu.n|
|00000020| 65 74 20 20 53 61 74 20 | 53 65 70 20 20 38 20 30 |et Sat |Sep 8 0|
|00000030| 39 3a 32 31 3a 32 30 20 | 31 39 39 30 0a 52 65 63 |9:21:20 |1990.Rec|
|00000040| 65 69 76 65 64 3a 20 66 | 72 6f 6d 20 63 73 2e 75 |eived: f|rom cs.u|
|00000050| 74 65 78 61 73 2e 65 64 | 75 20 62 79 20 75 75 6e |texas.ed|u by uun|
|00000060| 65 74 2e 75 75 2e 6e 65 | 74 20 28 35 2e 36 31 2f |et.uu.ne|t (5.61/|
|00000070| 31 2e 31 34 29 20 77 69 | 74 68 20 53 4d 54 50 20 |1.14) wi|th SMTP |
|00000080| 0a 09 69 64 20 41 41 31 | 38 33 37 37 3b 20 53 61 |..id AA1|8377; Sa|
|00000090| 74 2c 20 38 20 53 65 70 | 20 39 30 20 30 39 3a 32 |t, 8 Sep| 90 09:2|
|000000a0| 31 3a 32 30 20 2d 30 34 | 30 30 0a 50 6f 73 74 65 |1:20 -04|00.Poste|
|000000b0| 64 2d 44 61 74 65 3a 20 | 38 20 53 65 70 20 39 30 |d-Date: |8 Sep 90|
|000000c0| 20 30 30 3a 30 31 3a 30 | 30 20 47 4d 54 0a 52 65 | 00:01:0|0 GMT.Re|
|000000d0| 63 65 69 76 65 64 3a 20 | 62 79 20 63 73 2e 75 74 |ceived: |by cs.ut|
|000000e0| 65 78 61 73 2e 65 64 75 | 20 28 35 2e 36 34 2f 31 |exas.edu| (5.64/1|
|000000f0| 2e 37 36 29 20 0a 46 72 | 6f 6d 3a 20 73 77 61 72 |.76) .Fr|om: swar|
|00000100| 74 40 73 72 63 2e 64 65 | 63 2e 63 6f 6d 20 28 47 |t@src.de|c.com (G|
|00000110| 61 72 72 65 74 20 53 77 | 61 72 74 29 0a 4e 65 77 |arret Sw|art).New|
|00000120| 73 67 72 6f 75 70 73 3a | 20 63 6f 6d 70 2e 73 74 |sgroups:| comp.st|
|00000130| 64 2e 75 6e 69 78 0a 53 | 75 62 6a 65 63 74 3a 20 |d.unix.S|ubject: |
|00000140| 52 65 3a 20 53 74 61 6e | 64 61 72 64 73 20 55 70 |Re: Stan|dards Up|
|00000150| 64 61 74 65 2c 20 49 45 | 45 45 20 31 30 30 33 2e |date, IE|EE 1003.|
|00000160| 34 3a 20 52 65 61 6c 2d | 74 69 6d 65 20 45 78 74 |4: Real-|time Ext|
|00000170| 65 6e 73 69 6f 6e 73 0a | 4d 65 73 73 61 67 65 2d |ensions.|Message-|
|00000180| 49 64 3a 20 3c 34 39 37 | 40 75 73 65 6e 69 78 2e |Id: <497|@usenix.|
|00000190| 4f 52 47 3e 0a 52 65 66 | 65 72 65 6e 63 65 73 3a |ORG>.Ref|erences:|
|000001a0| 20 3c 34 38 31 40 75 73 | 65 6e 69 78 2e 4f 52 47 | <481@us|enix.ORG|
|000001b0| 3e 20 3c 34 39 35 40 75 | 73 65 6e 69 78 2e 4f 52 |> <495@u|senix.OR|
|000001c0| 47 3e 20 3c 34 38 38 40 | 75 73 65 6e 69 78 2e 4f |G> <488@|usenix.O|
|000001d0| 52 47 3e 20 3c 34 39 31 | 40 75 73 65 6e 69 78 2e |RG> <491|@usenix.|
|000001e0| 4f 52 47 3e 20 3c 34 39 | 33 40 75 73 65 6e 69 78 |ORG> <49|3@usenix|
|000001f0| 2e 4f 52 47 3e 20 3c 34 | 37 39 40 75 73 65 6e 69 |.ORG> <4|79@useni|
|00000200| 78 2e 4f 52 47 3e 0a 53 | 65 6e 64 65 72 3a 20 73 |x.ORG>.S|ender: s|
|00000210| 74 64 2d 75 6e 69 78 40 | 75 73 65 6e 69 78 2e 4f |td-unix@|usenix.O|
|00000220| 52 47 0a 58 2d 53 75 62 | 6d 69 73 73 69 6f 6e 73 |RG.X-Sub|missions|
|00000230| 3a 20 73 74 64 2d 75 6e | 69 78 40 75 75 6e 65 74 |: std-un|ix@uunet|
|00000240| 2e 75 75 2e 6e 65 74 0a | 44 61 74 65 3a 20 38 20 |.uu.net.|Date: 8 |
|00000250| 53 65 70 20 39 30 20 30 | 30 3a 30 31 3a 30 30 20 |Sep 90 0|0:01:00 |
|00000260| 47 4d 54 0a 52 65 70 6c | 79 2d 54 6f 3a 20 73 74 |GMT.Repl|y-To: st|
|00000270| 64 2d 75 6e 69 78 40 75 | 75 6e 65 74 2e 75 75 2e |d-unix@u|unet.uu.|
|00000280| 6e 65 74 0a 54 6f 3a 20 | 73 74 64 2d 75 6e 69 78 |net.To: |std-unix|
|00000290| 40 75 75 6e 65 74 2e 75 | 75 2e 6e 65 74 0a 0a 46 |@uunet.u|u.net..F|
|000002a0| 72 6f 6d 3a 20 20 73 77 | 61 72 74 40 73 72 63 2e |rom: sw|art@src.|
|000002b0| 64 65 63 2e 63 6f 6d 20 | 28 47 61 72 72 65 74 20 |dec.com |(Garret |
|000002c0| 53 77 61 72 74 29 0a 0a | 49 20 62 65 6c 69 65 76 |Swart)..|I believ|
|000002d0| 65 20 69 6e 20 70 75 74 | 74 69 6e 67 20 6c 6f 74 |e in put|ting lot|
|000002e0| 73 20 6f 66 20 69 6e 74 | 65 72 65 73 74 69 6e 67 |s of int|eresting|
|000002f0| 20 73 74 75 66 66 20 69 | 6e 20 74 68 65 20 66 69 | stuff i|n the fi|
|00000300| 6c 65 20 73 79 73 74 65 | 6d 20 6e 61 6d 65 0a 73 |le syste|m name.s|
|00000310| 70 61 63 65 20 62 75 74 | 20 49 20 64 6f 6e 27 74 |pace but| I don't|
|00000320| 20 62 65 6c 69 65 76 65 | 20 74 68 61 74 20 73 65 | believe| that se|
|00000330| 6d 61 70 68 6f 72 65 73 | 20 62 65 6c 6f 6e 67 20 |maphores| belong |
|00000340| 74 68 65 72 65 2e 20 20 | 54 68 65 20 72 65 61 73 |there. |The reas|
|00000350| 6f 6e 0a 49 20 64 6f 6e | 27 74 20 77 61 6e 74 20 |on.I don|'t want |
|00000360| 74 6f 20 70 75 74 20 73 | 65 6d 61 70 68 6f 72 65 |to put s|emaphore|
|00000370| 73 20 69 6e 20 74 68 65 | 20 6e 61 6d 65 20 73 70 |s in the| name sp|
|00000380| 61 63 65 20 69 73 20 74 | 68 65 20 73 61 6d 65 20 |ace is t|he same |
|00000390| 72 65 61 73 6f 6e 0a 49 | 20 64 6f 6e 27 74 20 77 |reason.I| don't w|
|000003a0| 61 6e 74 20 74 6f 20 70 | 75 74 20 6d 79 20 70 72 |ant to p|ut my pr|
|000003b0| 6f 67 72 61 6d 20 76 61 | 72 69 61 62 6c 65 73 20 |ogram va|riables |
|000003c0| 69 6e 20 74 68 65 20 6e | 61 6d 65 20 73 70 61 63 |in the n|ame spac|
|000003d0| 65 3a 20 20 49 20 77 61 | 6e 74 0a 74 6f 20 68 61 |e: I wa|nt.to ha|
|000003e0| 76 65 20 6c 6f 74 73 20 | 6f 66 20 74 68 65 6d 2c |ve lots |of them,|
|000003f0| 20 49 20 77 61 6e 74 20 | 74 6f 20 63 72 65 61 74 | I want |to creat|
|00000400| 65 20 61 6e 64 20 64 65 | 73 74 72 6f 79 20 74 68 |e and de|stroy th|
|00000410| 65 6d 20 76 65 72 79 20 | 71 75 69 63 6b 6c 79 0a |em very |quickly.|
|00000420| 61 6e 64 20 49 20 77 61 | 6e 74 20 74 6f 20 6f 70 |and I wa|nt to op|
|00000430| 65 72 61 74 65 20 6f 6e | 20 74 68 65 6d 20 65 76 |erate on| them ev|
|00000440| 65 6e 20 6d 6f 72 65 20 | 71 75 69 63 6b 6c 79 2e |en more |quickly.|
|00000450| 20 20 49 6e 20 6f 74 68 | 65 72 20 77 6f 72 64 73 | In oth|er words|
|00000460| 2c 20 74 68 65 0a 67 72 | 61 6e 75 6c 61 72 69 74 |, the.gr|anularit|
|00000470| 79 20 69 73 20 77 72 6f | 6e 67 2e 0a 0a 54 68 65 |y is wro|ng...The|
|00000480| 20 70 75 72 70 6f 73 65 | 20 6f 66 20 61 20 73 65 | purpose| of a se|
|00000490| 6d 61 70 68 6f 72 65 20 | 69 73 20 74 6f 20 73 79 |maphore |is to sy|
|000004a0| 6e 63 68 72 6f 6e 69 7a | 65 20 61 63 74 69 6f 6e |nchroniz|e action|
|000004b0| 73 20 6f 6e 20 61 6e 20 | 6f 62 6a 65 63 74 2e 0a |s on an |object..|
|000004c0| 57 68 61 74 20 6b 69 6e | 64 73 20 6f 66 20 6f 62 |What kin|ds of ob|
|000004d0| 6a 65 63 74 73 20 6d 69 | 67 68 74 20 6f 6e 65 20 |jects mi|ght one |
|000004e0| 77 61 6e 74 20 74 6f 20 | 73 79 6e 63 68 72 6f 6e |want to |synchron|
|000004f0| 69 7a 65 3f 20 20 47 65 | 6e 65 72 61 6c 6c 79 20 |ize? Ge|nerally |
|00000500| 74 68 65 0a 6f 62 6a 65 | 63 74 73 20 61 72 65 20 |the.obje|cts are |
|00000510| 65 69 74 68 65 72 20 4f | 53 20 73 75 70 70 6c 69 |either O|S suppli|
|00000520| 65 64 20 6c 69 6b 65 20 | 64 65 76 69 63 65 73 20 |ed like |devices |
|00000530| 6f 72 20 66 69 6c 65 73 | 2c 20 6f 72 20 75 73 65 |or files|, or use|
|00000540| 72 20 64 65 66 69 6e 65 | 64 0a 64 61 74 61 20 73 |r define|d.data s|
|00000550| 74 72 75 63 74 75 72 65 | 73 2e 20 20 54 68 65 20 |tructure|s. The |
|00000560| 74 79 70 69 63 61 6c 20 | 77 61 79 20 6f 66 20 73 |typical |way of s|
|00000570| 79 6e 63 68 72 6f 6e 69 | 7a 69 6e 67 20 66 69 6c |ynchroni|zing fil|
|00000580| 65 73 20 61 6e 64 20 64 | 65 76 69 63 65 73 0a 69 |es and d|evices.i|
|00000590| 73 20 74 6f 20 75 73 65 | 20 61 64 76 69 73 6f 72 |s to use| advisor|
|000005a0| 79 20 6c 6f 63 6b 73 20 | 6f 72 20 74 68 65 20 22 |y locks |or the "|
|000005b0| 65 78 63 6c 75 73 69 76 | 65 20 75 73 65 22 20 6d |exclusiv|e use" m|
|000005c0| 6f 64 65 20 6f 6e 20 74 | 68 65 20 64 65 76 69 63 |ode on t|he devic|
|000005d0| 65 2e 0a 54 68 65 20 6d | 6f 72 65 20 64 69 66 66 |e..The m|ore diff|
|000005e0| 69 63 75 6c 74 20 63 61 | 73 65 20 61 6e 64 20 74 |icult ca|se and t|
|000005f0| 68 65 20 6f 6e 65 20 66 | 6f 72 20 77 68 69 63 68 |he one f|or which|
|00000600| 20 73 65 6d 61 70 68 6f | 72 65 73 20 77 65 72 65 | semapho|res were|
|00000610| 20 69 6e 76 65 6e 74 65 | 64 2c 0a 61 6e 64 20 6c | invente|d,.and l|
|00000620| 61 74 65 72 20 61 64 64 | 65 64 20 74 6f 20 55 6e |ater add|ed to Un|
|00000630| 69 78 2c 20 69 73 20 74 | 68 61 74 20 6f 66 20 73 |ix, is t|hat of s|
|00000640| 79 6e 63 68 72 6f 6e 69 | 7a 69 6e 67 20 75 73 65 |ynchroni|zing use|
|00000650| 72 20 64 61 74 61 20 73 | 74 72 75 63 74 75 72 65 |r data s|tructure|
|00000660| 73 2e 0a 0a 49 6e 20 55 | 6e 69 78 2c 20 75 73 65 |s...In U|nix, use|
|00000670| 72 20 64 61 74 61 20 73 | 74 72 75 63 74 75 72 65 |r data s|tructure|
|00000680| 73 20 6d 61 79 20 6c 69 | 76 65 20 65 69 74 68 65 |s may li|ve eithe|
|00000690| 72 20 69 6e 20 61 20 70 | 72 6f 63 65 73 73 27 73 |r in a p|rocess's|
|000006a0| 20 70 72 69 76 61 74 65 | 0a 6d 65 6d 6f 72 79 20 | private|.memory |
|000006b0| 6f 72 20 69 6e 20 61 20 | 73 68 61 72 65 64 20 6d |or in a |shared m|
|000006c0| 65 6d 6f 72 79 20 73 65 | 67 6d 65 6e 74 2e 20 20 |emory se|gment. |
|000006d0| 49 6e 20 62 6f 74 68 20 | 63 61 73 65 73 20 74 68 |In both |cases th|
|000006e0| 65 72 65 20 61 72 65 20 | 70 72 6f 62 61 62 6c 79 |ere are |probably|
|000006f0| 0a 6d 61 6e 79 20 64 69 | 66 66 65 72 65 6e 74 20 |.many di|fferent |
|00000700| 64 61 74 61 20 73 74 72 | 75 63 74 75 72 65 73 20 |data str|uctures |
|00000710| 69 6e 20 74 68 61 74 20 | 6d 65 6d 6f 72 79 20 61 |in that |memory a|
|00000720| 6e 64 20 6d 61 6e 79 20 | 6f 66 20 74 68 65 73 65 |nd many |of these|
|00000730| 20 64 61 74 61 0a 73 74 | 72 75 63 74 75 72 65 73 | data.st|ructures|
|00000740| 20 6d 61 79 20 6e 65 65 | 64 20 74 6f 20 62 65 20 | may nee|d to be |
|00000750| 73 79 6e 63 68 72 6f 6e | 69 7a 65 64 2e 20 20 46 |synchron|ized. F|
|00000760| 6f 72 20 6d 61 78 69 6d | 75 6d 20 63 6f 6e 63 75 |or maxim|um concu|
|00000770| 72 72 65 6e 63 79 20 74 | 68 65 0a 70 72 6f 67 72 |rrency t|he.progr|
|00000780| 61 6d 6d 65 72 20 6d 61 | 79 20 77 69 73 68 20 74 |ammer ma|y wish t|
|00000790| 6f 20 73 79 6e 63 68 72 | 6f 6e 69 7a 65 20 65 61 |o synchr|onize ea|
|000007a0| 63 68 20 64 61 74 61 20 | 73 74 72 75 63 74 75 72 |ch data |structur|
|000007b0| 65 20 77 69 74 68 20 69 | 74 73 20 6f 77 6e 0a 73 |e with i|ts own.s|
|000007c0| 65 6d 61 70 68 6f 72 65 | 2e 20 20 49 6e 20 6d 61 |emaphore|. In ma|
|000007d0| 6e 79 20 61 70 70 6c 69 | 63 61 74 69 6f 6e 73 20 |ny appli|cations |
|000007e0| 74 68 65 73 65 20 64 61 | 74 61 20 73 74 72 75 63 |these da|ta struc|
|000007f0| 74 75 72 65 73 20 6d 61 | 79 20 63 6f 6d 65 20 61 |tures ma|y come a|
|00000800| 6e 64 0a 67 6f 20 76 65 | 72 79 20 71 75 69 63 6b |nd.go ve|ry quick|
|00000810| 6c 79 20 61 6e 64 20 74 | 68 65 20 65 78 70 65 6e |ly and t|he expen|
|00000820| 73 65 20 6f 66 20 63 72 | 65 61 74 69 6e 67 20 61 |se of cr|eating a|
|00000830| 20 73 65 6d 61 70 68 6f | 72 65 20 74 6f 20 73 79 | semapho|re to sy|
|00000840| 6e 63 68 72 6f 6e 69 7a | 65 0a 74 68 65 20 64 61 |nchroniz|e.the da|
|00000850| 74 61 20 63 61 6e 20 62 | 65 20 69 6d 70 6f 72 74 |ta can b|e import|
|00000860| 61 6e 74 20 66 61 63 74 | 6f 72 20 69 6e 20 74 68 |ant fact|or in th|
|00000870| 65 20 70 65 72 66 6f 72 | 6d 61 6e 63 65 20 6f 66 |e perfor|mance of|
|00000880| 20 74 68 65 20 61 70 70 | 6c 69 63 61 74 69 6f 6e | the app|lication|
|00000890| 2e 0a 0a 49 74 20 74 68 | 75 73 20 73 65 65 6d 73 |...It th|us seems|
|000008a0| 20 6d 6f 72 65 20 6e 61 | 74 75 72 61 6c 20 74 6f | more na|tural to|
|000008b0| 20 61 6c 6c 6f 77 20 73 | 65 6d 61 70 68 6f 72 65 | allow s|emaphore|
|000008c0| 73 20 74 6f 20 62 65 20 | 65 66 66 69 63 69 65 6e |s to be |efficien|
|000008d0| 74 6c 79 0a 61 6c 6c 6f | 63 61 74 65 64 20 61 6c |tly.allo|cated al|
|000008e0| 6f 6e 67 20 77 69 74 68 | 20 74 68 65 20 64 61 74 |ong with| the dat|
|000008f0| 61 20 74 68 61 74 20 74 | 68 65 79 20 61 72 65 20 |a that t|hey are |
|00000900| 64 65 73 69 67 6e 65 64 | 20 74 6f 20 73 79 6e 63 |designed| to sync|
|00000910| 68 72 6f 6e 69 7a 65 2e | 0a 54 68 61 74 20 69 73 |hronize.|.That is|
|00000920| 2c 20 61 6c 6c 6f 77 20 | 74 68 65 6d 20 74 6f 20 |, allow |them to |
|00000930| 62 65 20 61 6c 6c 6f 63 | 61 74 65 64 20 69 6e 20 |be alloc|ated in |
|00000940| 61 20 70 72 6f 63 65 73 | 73 27 73 20 70 72 69 76 |a proces|s's priv|
|00000950| 61 74 65 20 61 64 64 72 | 65 73 73 0a 73 70 61 63 |ate addr|ess.spac|
|00000960| 65 20 6f 72 20 69 6e 20 | 61 20 6d 61 70 70 65 64 |e or in |a mapped|
|00000970| 20 73 68 61 72 65 64 20 | 6d 65 6d 6f 72 79 20 73 | shared |memory s|
|00000980| 65 67 6d 65 6e 74 2e 20 | 20 41 20 73 68 61 72 65 |egment. | A share|
|00000990| 64 20 6d 65 6d 6f 72 79 | 20 73 65 67 6d 65 6e 74 |d memory| segment|
|000009a0| 0a 69 73 20 61 20 6d 75 | 63 68 20 6c 61 72 67 65 |.is a mu|ch large|
|000009b0| 72 20 67 72 61 69 6e 20 | 6f 62 6a 65 63 74 2c 20 |r grain |object, |
|000009c0| 63 72 65 61 74 69 6e 67 | 2c 20 64 65 73 74 72 6f |creating|, destro|
|000009d0| 79 69 6e 67 20 61 6e 64 | 20 6d 61 70 70 69 6e 67 |ying and| mapping|
|000009e0| 20 74 68 65 6d 0a 63 61 | 6e 20 62 65 20 6d 75 63 | them.ca|n be muc|
|000009f0| 68 20 6d 6f 72 65 20 65 | 78 70 65 6e 73 69 76 65 |h more e|xpensive|
|00000a00| 20 74 68 61 6e 20 63 72 | 65 61 74 69 6e 67 2c 20 | than cr|eating, |
|00000a10| 64 65 73 74 72 6f 79 69 | 6e 67 20 6f 72 20 75 73 |destroyi|ng or us|
|00000a20| 69 6e 67 20 61 0a 73 65 | 6d 61 70 68 6f 72 65 20 |ing a.se|maphore |
|00000a30| 61 6e 64 20 74 68 65 73 | 65 20 73 65 67 6d 65 6e |and thes|e segmen|
|00000a40| 74 73 20 61 72 65 20 67 | 65 6e 65 72 61 6c 6c 79 |ts are g|enerally|
|00000a50| 20 69 6d 70 6f 72 74 61 | 6e 74 20 65 6e 6f 75 67 | importa|nt enoug|
|00000a60| 68 20 74 6f 20 74 68 65 | 0a 61 70 70 6c 69 63 61 |h to the|.applica|
|00000a70| 74 69 6f 6e 20 74 6f 20 | 68 61 76 65 20 73 65 6e |tion to |have sen|
|00000a80| 73 69 62 6c 65 20 6e 61 | 6d 65 73 2e 20 20 54 68 |sible na|mes. Th|
|00000a90| 75 73 20 70 75 74 74 69 | 6e 67 20 61 20 73 68 61 |us putti|ng a sha|
|00000aa0| 72 65 64 20 6d 65 6d 6f | 72 79 0a 73 65 67 6d 65 |red memo|ry.segme|
|00000ab0| 6e 74 20 69 6e 20 74 68 | 65 20 6e 61 6d 65 20 73 |nt in th|e name s|
|00000ac0| 70 61 63 65 20 73 65 65 | 6d 73 20 72 65 61 73 6f |pace see|ms reaso|
|00000ad0| 6e 61 62 6c 65 2e 20 20 | 0a 0a 46 6f 72 20 65 78 |nable. |..For ex|
|00000ae0| 61 6d 70 6c 65 2c 20 61 | 20 64 61 74 61 20 62 61 |ample, a| data ba|
|00000af0| 73 65 20 6c 69 62 72 61 | 72 79 20 6d 61 79 20 75 |se libra|ry may u|
|00000b00| 73 65 20 61 20 73 68 61 | 72 65 64 20 6d 65 6d 62 |se a sha|red memb|
|00000b10| 65 72 20 73 65 67 6d 65 | 6e 74 20 6e 61 6d 65 64 |er segme|nt named|
|00000b20| 0a 2f 75 73 72 2f 6c 6f | 63 61 6c 2f 6c 69 62 2f |./usr/lo|cal/lib/|
|00000b30| 64 62 6d 2f 70 65 72 73 | 6f 6e 6e 65 6c 2f 62 75 |dbm/pers|onnel/bu|
|00000b40| 66 70 6f 6f 6c 20 74 6f | 20 68 6f 6c 64 20 74 68 |fpool to| hold th|
|00000b50| 65 20 62 75 66 66 65 72 | 20 70 6f 6f 6c 20 66 6f |e buffer| pool fo|
|00000b60| 72 20 74 68 65 0a 70 65 | 72 73 6f 6e 6e 65 6c 20 |r the.pe|rsonnel |
|00000b70| 64 65 70 61 72 74 6d 65 | 6e 74 27 73 20 64 61 74 |departme|nt's dat|
|00000b80| 61 20 62 61 73 65 2e 20 | 20 54 68 65 20 64 61 74 |a base. | The dat|
|00000b90| 61 20 62 61 73 65 20 6c | 69 62 72 61 72 79 20 77 |a base l|ibrary w|
|00000ba0| 6f 75 6c 64 20 6d 61 70 | 0a 74 68 65 20 62 75 66 |ould map|.the buf|
|00000bb0| 66 65 72 20 70 6f 6f 6c | 20 69 6e 74 6f 20 65 61 |fer pool| into ea|
|00000bc0| 63 68 20 63 6c 69 65 6e | 74 27 73 20 61 64 64 72 |ch clien|t's addr|
|00000bd0| 65 73 73 20 73 70 61 63 | 65 20 61 6c 6c 6f 77 69 |ess spac|e allowi|
|00000be0| 6e 67 20 6d 61 6e 79 20 | 64 61 74 61 0a 62 61 73 |ng many |data.bas|
|00000bf0| 65 20 63 6c 69 65 6e 74 | 20 70 72 6f 67 72 61 6d |e client| program|
|00000c00| 73 20 74 6f 20 65 66 66 | 69 63 69 65 6e 74 6c 79 |s to eff|iciently|
|00000c10| 20 61 63 63 65 73 73 20 | 74 68 65 20 64 61 74 61 | access |the data|
|00000c20| 20 62 61 73 65 2e 20 20 | 45 61 63 68 20 70 61 67 | base. |Each pag|
|00000c30| 65 0a 69 6e 20 74 68 65 | 20 62 75 66 66 65 72 20 |e.in the| buffer |
|00000c40| 70 6f 6f 6c 20 61 6e 64 | 20 65 61 63 68 20 74 72 |pool and| each tr|
|00000c50| 61 6e 73 61 63 74 69 6f | 6e 20 77 6f 75 6c 64 20 |ansactio|n would |
|00000c60| 68 61 76 65 20 69 74 73 | 20 6f 77 6e 20 73 65 74 |have its| own set|
|00000c70| 20 6f 66 0a 73 65 6d 61 | 70 68 6f 72 65 73 20 75 | of.sema|phores u|
|00000c80| 73 65 64 20 74 6f 20 73 | 79 6e 63 68 72 6f 6e 69 |sed to s|ynchroni|
|00000c90| 7a 65 20 61 63 63 65 73 | 73 20 74 6f 20 74 68 65 |ze acces|s to the|
|00000ca0| 20 70 61 67 65 20 69 6e | 20 74 68 65 20 70 6f 6f | page in| the poo|
|00000cb0| 6c 20 6f 72 20 74 68 65 | 0a 73 74 61 74 65 20 6f |l or the|.state o|
|00000cc0| 66 20 61 20 74 72 61 6e | 73 61 63 74 69 6f 6e 2e |f a tran|saction.|
|00000cd0| 20 20 47 69 76 69 6e 67 | 20 74 68 65 20 62 75 66 | Giving| the buf|
|00000ce0| 66 65 72 20 70 6f 6f 6c | 20 61 20 6e 61 6d 65 20 |fer pool| a name |
|00000cf0| 69 73 20 6e 6f 20 70 72 | 6f 62 6c 65 6d 2c 0a 62 |is no pr|oblem,.b|
|00000d00| 75 74 20 67 69 76 69 6e | 67 20 65 61 63 68 20 73 |ut givin|g each s|
|00000d10| 65 6d 61 70 68 6f 72 65 | 20 61 20 6e 61 6d 65 20 |emaphore| a name |
|00000d20| 69 73 20 6d 75 63 68 20 | 6d 6f 72 65 20 6f 66 20 |is much |more of |
|00000d30| 61 20 68 61 73 73 6c 65 | 2e 0a 0a 5b 41 73 69 64 |a hassle|...[Asid|
|00000d40| 65 3a 20 20 41 6e 6f 74 | 68 65 72 20 77 61 79 20 |e: Anot|her way |
|00000d50| 6f 66 20 73 74 72 75 63 | 74 75 72 69 6e 67 20 73 |of struc|turing s|
|00000d60| 75 63 68 20 61 20 64 61 | 74 61 20 62 61 73 65 20 |uch a da|ta base |
|00000d70| 6c 69 62 72 61 72 79 20 | 69 73 20 61 73 0a 61 6e |library |is as.an|
|00000d80| 20 52 50 43 20 73 74 79 | 6c 65 20 6d 75 6c 74 69 | RPC sty|le multi|
|00000d90| 2d 74 68 72 65 61 64 65 | 64 20 73 65 72 76 65 72 |-threade|d server|
|00000da0| 2e 20 20 54 68 69 73 20 | 61 6c 6c 6f 77 73 20 61 |. This |allows a|
|00000db0| 63 63 65 73 73 20 74 6f | 20 74 68 65 20 64 61 74 |ccess to| the dat|
|00000dc0| 61 0a 62 61 73 65 20 66 | 72 6f 6d 20 72 65 6d 6f |a.base f|rom remo|
|00000dd0| 74 65 20 6d 61 63 68 69 | 6e 65 73 20 61 6e 64 20 |te machi|nes and |
|00000de0| 61 6c 6c 6f 77 73 20 65 | 61 73 69 65 72 20 73 6f |allows e|asier so|
|00000df0| 6c 75 74 69 6f 6e 73 20 | 74 6f 20 74 68 65 20 73 |lutions |to the s|
|00000e00| 65 63 75 72 69 74 79 0a | 61 6e 64 20 66 61 69 6c |ecurity.|and fail|
|00000e10| 75 72 65 20 70 72 6f 62 | 6c 65 6d 73 20 69 6e 68 |ure prob|lems inh|
|00000e20| 65 72 65 6e 74 20 69 6e | 20 74 68 65 20 73 68 61 |erent in| the sha|
|00000e30| 72 65 64 20 6d 65 6d 6f | 72 79 20 61 70 70 72 6f |red memo|ry appro|
|00000e40| 61 63 68 2e 20 20 48 6f | 77 65 76 65 72 0a 74 68 |ach. Ho|wever.th|
|00000e50| 65 20 73 68 61 72 65 64 | 20 6d 65 6d 6f 72 79 20 |e shared| memory |
|00000e60| 61 70 70 72 6f 61 63 68 | 20 68 61 73 20 61 20 6d |approach| has a m|
|00000e70| 61 6a 6f 72 20 70 65 72 | 66 6f 72 6d 61 6e 63 65 |ajor per|formance|
|00000e80| 20 61 64 76 61 6e 74 61 | 67 65 20 66 6f 72 20 73 | advanta|ge for s|
|00000e90| 79 73 74 65 6d 73 0a 74 | 68 61 74 20 64 6f 20 6e |ystems.t|hat do n|
|00000ea0| 6f 74 20 73 75 70 70 6f | 72 74 20 75 6c 74 72 61 |ot suppo|rt ultra|
|00000eb0| 2d 66 61 73 74 20 52 50 | 43 73 2e 20 20 41 6e 6f |-fast RP|Cs. Ano|
|00000ec0| 74 68 65 72 20 61 70 70 | 72 6f 61 63 68 20 69 73 |ther app|roach is|
|00000ed0| 20 74 6f 20 72 75 6e 20 | 74 68 65 0a 6c 69 62 72 | to run |the.libr|
|00000ee0| 61 72 79 20 69 6e 20 61 | 6e 20 69 6e 6e 65 72 20 |ary in a|n inner |
|00000ef0| 6d 6f 64 65 2e 20 20 28 | 55 6e 69 78 20 68 61 73 |mode. (|Unix has|
|00000f00| 20 6f 6e 65 20 69 6e 6e | 65 72 20 6d 6f 64 65 20 | one inn|er mode |
|00000f10| 63 61 6c 6c 65 64 20 74 | 68 65 20 6b 65 72 6e 65 |called t|he kerne|
|00000f20| 6c 2c 0a 56 4d 53 20 68 | 61 73 20 33 2c 20 4d 75 |l,.VMS h|as 3, Mu|
|00000f30| 6c 74 69 63 73 20 68 61 | 64 20 6d 61 6e 79 2e 29 |ltics ha|d many.)|
|00000f40| 20 20 54 68 69 73 20 73 | 6f 6c 76 65 73 20 74 68 | This s|olves th|
|00000f50| 65 20 73 65 63 75 72 69 | 74 79 20 61 6e 64 20 66 |e securi|ty and f|
|00000f60| 61 69 6c 75 72 65 0a 70 | 72 6f 62 6c 65 6d 73 20 |ailure.p|roblems |
|00000f70| 6f 66 20 74 68 65 20 73 | 68 61 72 65 64 20 73 65 |of the s|hared se|
|00000f80| 67 6d 65 6e 74 73 20 62 | 75 74 20 69 74 20 69 73 |gments b|ut it is|
|00000f90| 20 67 65 6e 65 72 61 6c | 6c 79 20 64 69 66 66 69 | general|ly diffi|
|00000fa0| 63 75 6c 74 20 66 6f 72 | 20 6d 65 72 65 0a 6d 6f |cult for| mere.mo|
|00000fb0| 72 74 61 6c 73 20 74 6f | 20 77 72 69 74 65 20 74 |rtals to| write t|
|00000fc0| 68 65 69 72 20 6f 77 6e | 20 69 6e 6e 65 72 20 6d |heir own| inner m|
|00000fd0| 6f 64 65 20 6c 69 62 72 | 61 72 69 65 73 2e 5d 0a |ode libr|aries.].|
|00000fe0| 0a 4f 6e 65 20 6f 74 68 | 65 72 20 69 73 73 75 65 |.One oth|er issue|
|00000ff0| 20 74 68 61 74 20 6d 61 | 79 20 63 61 75 73 65 20 | that ma|y cause |
|00001000| 6f 6e 65 20 74 6f 20 77 | 61 6e 74 20 74 6f 20 75 |one to w|ant to u|
|00001010| 6e 69 66 79 20 61 6c 6c | 20 6f 62 6a 65 63 74 73 |nify all| objects|
|00001020| 20 69 6e 0a 74 68 65 20 | 66 69 6c 65 20 73 79 73 | in.the |file sys|
|00001030| 74 65 6d 2c 20 61 74 20 | 6c 65 61 73 74 20 61 74 |tem, at |least at|
|00001040| 20 74 68 65 20 6c 65 76 | 65 6c 20 6f 66 20 75 73 | the lev|el of us|
|00001050| 69 6e 67 20 66 69 6c 65 | 20 64 65 73 63 72 69 70 |ing file| descrip|
|00001060| 74 6f 72 73 20 74 6f 0a | 72 65 66 65 72 20 74 6f |tors to.|refer to|
|00001070| 20 61 6c 6c 20 6f 62 6a | 65 63 74 73 20 69 66 20 | all obj|ects if |
|00001080| 6e 6f 74 20 67 6f 69 6e | 67 20 73 6f 20 66 61 72 |not goin|g so far|
|00001090| 20 61 73 20 74 6f 20 70 | 75 74 20 61 6c 6c 20 6f | as to p|ut all o|
|000010a0| 62 6a 65 63 74 73 20 69 | 6e 20 74 68 65 0a 6e 61 |bjects i|n the.na|
|000010b0| 6d 65 20 73 70 61 63 65 | 2c 20 69 73 20 74 68 65 |me space|, is the|
|000010c0| 20 66 61 63 74 20 74 68 | 61 74 20 73 69 6e 67 6c | fact th|at singl|
|000010d0| 65 20 74 68 72 65 61 64 | 65 64 20 70 72 6f 67 72 |e thread|ed progr|
|000010e0| 61 6d 6d 69 6e 67 20 69 | 73 20 6d 75 63 68 20 6e |amming i|s much n|
|000010f0| 69 63 65 72 0a 69 66 20 | 74 68 65 72 65 20 69 73 |icer.if |there is|
|00001100| 20 61 20 73 69 6e 67 6c | 65 20 70 72 69 6d 69 74 | a singl|e primit|
|00001110| 69 76 65 20 74 68 61 74 | 20 77 69 6c 6c 20 77 61 |ive that| will wa|
|00001120| 69 74 20 66 6f 72 20 41 | 4e 59 20 65 76 65 6e 74 |it for A|NY event|
|00001130| 20 74 68 61 74 20 74 68 | 65 0a 70 72 6f 63 65 73 | that th|e.proces|
|00001140| 73 20 6d 61 79 20 62 65 | 20 69 6e 74 65 72 65 73 |s may be| interes|
|00001150| 74 65 64 20 69 6e 20 28 | 65 2e 67 2e 20 74 68 65 |ted in (|e.g. the|
|00001160| 20 34 2e 32 42 53 44 20 | 73 65 6c 65 63 74 20 63 | 4.2BSD |select c|
|00001170| 61 6c 6c 2e 29 20 20 54 | 68 69 73 20 63 61 6c 6c |all.) T|his call|
|00001180| 0a 69 73 20 75 73 65 66 | 75 6c 20 69 66 20 6f 6e |.is usef|ul if on|
|00001190| 65 20 69 73 20 74 6f 20 | 77 72 69 74 65 20 61 20 |e is to |write a |
|000011a0| 73 69 6e 67 6c 65 20 74 | 68 72 65 61 64 65 64 20 |single t|hreaded |
|000011b0| 70 72 6f 67 72 61 6d 20 | 74 68 61 74 20 64 6f 65 |program |that doe|
|000011c0| 73 6e 27 74 0a 62 75 73 | 79 20 77 61 69 74 20 77 |sn't.bus|y wait w|
|000011d0| 68 65 6e 20 69 74 20 68 | 61 73 20 6e 6f 74 68 69 |hen it h|as nothi|
|000011e0| 6e 67 20 74 6f 20 64 6f | 20 62 75 74 20 61 6c 73 |ng to do| but als|
|000011f0| 6f 20 77 6f 6e 27 74 20 | 62 6c 6f 63 6b 20 77 68 |o won't |block wh|
|00001200| 65 6e 20 61 6e 20 65 76 | 65 6e 74 0a 6f 66 20 69 |en an ev|ent.of i|
|00001210| 6e 74 65 72 65 73 74 20 | 68 61 73 20 6f 63 63 75 |nterest |has occu|
|00001220| 72 72 65 64 2e 20 20 57 | 69 74 68 20 74 68 65 20 |rred. W|ith the |
|00001230| 61 64 76 65 6e 74 20 6f | 66 20 6d 75 6c 74 69 2d |advent o|f multi-|
|00001240| 74 68 72 65 61 64 65 64 | 20 70 72 6f 67 72 61 6d |threaded| program|
|00001250| 6d 69 6e 67 0a 74 68 65 | 20 73 69 6e 67 6c 65 20 |ming.the| single |
|00001260| 6d 75 6c 74 69 2d 77 61 | 79 20 77 61 69 74 20 70 |multi-wa|y wait p|
|00001270| 72 69 6d 69 74 69 76 65 | 20 69 73 20 6e 6f 20 6c |rimitive| is no l|
|00001280| 6f 6e 67 65 72 20 6e 65 | 65 64 65 64 20 61 73 20 |onger ne|eded as |
|00001290| 69 6e 73 74 65 61 64 0a | 6f 6e 65 20 63 61 6e 20 |instead.|one can |
|000012a0| 63 72 65 61 74 65 20 61 | 20 73 65 70 61 72 61 74 |create a| separat|
|000012b0| 65 20 74 68 72 65 61 64 | 20 65 61 63 68 20 62 6c |e thread| each bl|
|000012c0| 6f 63 6b 69 6e 67 20 66 | 6f 72 20 61 6e 20 65 76 |ocking f|or an ev|
|000012d0| 65 6e 74 20 6f 66 20 69 | 6e 74 65 72 65 73 74 0a |ent of i|nterest.|
|000012e0| 61 6e 64 20 70 72 6f 63 | 65 73 73 69 6e 67 20 69 |and proc|essing i|
|000012f0| 74 2e 20 20 4d 75 6c 74 | 69 2d 77 61 79 20 77 61 |t. Mult|i-way wa|
|00001300| 69 74 69 6e 67 20 69 73 | 20 61 20 70 72 6f 62 6c |iting is| a probl|
|00001310| 65 6d 20 69 66 20 73 69 | 6e 67 6c 65 20 74 68 72 |em if si|ngle thr|
|00001320| 65 61 64 65 64 0a 70 72 | 6f 67 72 61 6d 73 20 61 |eaded.pr|ograms a|
|00001330| 72 65 20 67 6f 69 6e 67 | 20 74 6f 20 67 65 74 20 |re going| to get |
|00001340| 6d 61 78 69 6d 75 6d 20 | 75 73 65 20 6f 75 74 20 |maximum |use out |
|00001350| 6f 66 20 74 68 65 20 66 | 61 63 69 6c 69 74 79 2e |of the f|acility.|
|00001360| 0a 0a 49 27 76 65 20 73 | 70 6f 6b 65 6e 20 74 6f |..I've s|poken to|
|00001370| 20 61 20 6e 75 6d 62 65 | 72 20 6f 66 20 70 65 6f | a numbe|r of peo|
|00001380| 70 6c 65 20 69 6e 20 31 | 30 30 33 2e 34 20 61 62 |ple in 1|003.4 ab|
|00001390| 6f 75 74 20 74 68 65 73 | 65 20 69 64 65 61 73 2e |out thes|e ideas.|
|000013a0| 20 20 49 20 61 6d 0a 6e | 6f 74 20 73 75 72 65 20 | I am.n|ot sure |
|000013b0| 77 68 65 74 68 65 72 20 | 69 74 20 70 6c 61 79 65 |whether |it playe|
|000013c0| 64 20 61 6e 79 20 70 61 | 72 74 20 69 6e 20 74 68 |d any pa|rt in th|
|000013d0| 65 69 72 20 64 65 63 69 | 73 69 6f 6e 2e 0a 0a 4a |eir deci|sion...J|
|000013e0| 75 73 74 20 74 6f 20 70 | 72 6f 76 65 20 74 68 61 |ust to p|rove tha|
|000013f0| 74 20 49 20 61 6d 20 61 | 20 70 72 6f 2d 6e 61 6d |t I am a| pro-nam|
|00001400| 65 20 73 70 61 63 65 20 | 6b 69 6e 64 20 6f 66 20 |e space |kind of |
|00001410| 67 75 79 2c 20 49 20 61 | 6d 20 63 75 72 72 65 6e |guy, I a|m curren|
|00001420| 74 6c 79 0a 77 6f 72 6b | 69 6e 67 20 6f 6e 20 61 |tly.work|ing on a|
|00001430| 6e 64 20 75 73 69 6e 67 | 20 61 6e 20 65 78 70 65 |nd using| an expe|
|00001440| 72 69 6d 65 6e 74 61 6c | 20 66 69 6c 65 20 73 79 |rimental| file sy|
|00001450| 73 74 65 6d 20 63 61 6c | 6c 65 64 20 45 63 68 6f |stem cal|led Echo|
|00001460| 20 74 68 61 74 0a 69 6e | 74 65 67 72 61 74 65 73 | that.in|tegrates|
|00001470| 20 74 68 65 20 49 6e 74 | 65 72 6e 65 74 20 44 6f | the Int|ernet Do|
|00001480| 6d 61 69 6e 20 6e 61 6d | 65 20 73 65 72 76 69 63 |main nam|e servic|
|00001490| 65 20 66 6f 72 20 61 63 | 63 65 73 73 20 74 6f 20 |e for ac|cess to |
|000014a0| 67 6c 6f 62 61 6c 20 6e | 61 6d 65 73 2c 0a 6f 75 |global n|ames,.ou|
|000014b0| 72 20 69 6e 74 65 72 6e | 61 6c 20 68 69 67 68 65 |r intern|al highe|
|000014c0| 72 20 70 65 72 66 6f 72 | 6d 61 6e 63 65 20 6e 61 |r perfor|mance na|
|000014d0| 6d 65 20 73 65 72 76 69 | 63 65 20 66 6f 72 20 68 |me servi|ce for h|
|000014e0| 69 67 68 6c 79 20 61 76 | 61 69 6c 61 62 6c 65 0a |ighly av|ailable.|
|000014f0| 6e 61 6d 69 6e 67 20 6f | 66 20 61 72 62 69 74 72 |naming o|f arbitr|
|00001500| 61 72 79 20 6f 62 6a 65 | 63 74 73 2c 20 6f 75 72 |ary obje|cts, our|
|00001510| 20 65 78 70 65 72 69 6d | 65 6e 74 61 6c 20 66 61 | experim|ental fa|
|00001520| 75 6c 74 20 74 6f 6c 65 | 72 61 6e 74 2c 20 6c 6f |ult tole|rant, lo|
|00001530| 67 20 62 61 73 65 64 2c | 0a 64 69 73 74 72 69 62 |g based,|.distrib|
|00001540| 75 74 65 64 20 66 69 6c | 65 20 73 65 72 76 69 63 |uted fil|e servic|
|00001550| 65 20 77 69 74 68 20 72 | 65 61 64 2f 77 72 69 74 |e with r|ead/writ|
|00001560| 65 20 63 6f 6e 73 69 73 | 74 65 6e 63 79 20 61 6e |e consis|tency an|
|00001570| 64 20 75 6e 69 76 65 72 | 73 61 6c 0a 77 72 69 74 |d univer|sal.writ|
|00001580| 65 20 62 61 63 6b 20 66 | 6f 72 20 66 69 6c 65 20 |e back f|or file |
|00001590| 73 74 6f 72 61 67 65 2c | 20 61 6e 64 20 61 75 74 |storage,| and aut|
|000015a0| 6f 2d 6d 6f 75 6e 74 69 | 6e 67 20 4e 46 53 20 66 |o-mounti|ng NFS f|
|000015b0| 6f 72 20 61 63 63 65 73 | 73 69 6e 67 20 6f 74 68 |or acces|sing oth|
|000015c0| 65 72 0a 73 79 73 74 65 | 6d 73 2e 0a 0a 4f 62 6a |er.syste|ms...Obj|
|000015d0| 65 63 74 73 20 74 68 61 | 74 20 61 72 65 20 6e 61 |ects tha|t are na|
|000015e0| 6d 65 64 20 69 6e 20 6f | 75 72 20 6e 61 6d 65 20 |med in o|ur name |
|000015f0| 73 70 61 63 65 20 63 75 | 72 72 65 6e 74 6c 79 20 |space cu|rrently |
|00001600| 69 6e 63 6c 75 64 65 3a | 0a 0a 20 20 20 68 6f 73 |include:|.. hos|
|00001610| 74 73 2c 20 75 73 65 72 | 73 2c 20 67 72 6f 75 70 |ts, user|s, group|
|00001620| 73 2c 20 6e 65 74 77 6f | 72 6b 20 73 65 72 76 65 |s, netwo|rk serve|
|00001630| 72 73 2c 20 6e 65 74 77 | 6f 72 6b 20 73 65 72 76 |rs, netw|ork serv|
|00001640| 69 63 65 73 20 28 61 20 | 66 61 75 6c 74 0a 20 20 |ices (a |fault. |
|00001650| 20 74 6f 6c 65 72 61 6e | 74 20 6e 65 74 77 6f 72 | toleran|t networ|
|00001660| 6b 20 73 65 72 76 69 63 | 65 20 69 73 20 67 65 6e |k servic|e is gen|
|00001670| 65 72 61 6c 6c 79 20 70 | 72 6f 76 69 64 65 64 20 |erally p|rovided |
|00001680| 62 79 20 73 65 76 65 72 | 61 6c 20 73 65 72 76 65 |by sever|al serve|
|00001690| 72 73 29 2c 0a 20 20 20 | 61 6e 79 20 65 76 65 72 |rs),. |any ever|
|000016a0| 79 20 76 65 72 73 69 6f | 6e 20 6f 66 20 61 6e 79 |y versio|n of any|
|000016b0| 20 73 6f 75 72 63 65 20 | 6f 72 20 6f 62 6a 65 63 | source |or objec|
|000016c0| 74 20 66 69 6c 65 20 6b | 6e 6f 77 6e 20 62 79 20 |t file k|nown by |
|000016d0| 6f 75 72 20 73 6f 75 72 | 63 65 0a 20 20 20 63 6f |our sour|ce. co|
|000016e0| 64 65 20 63 6f 6e 74 72 | 6f 6c 20 73 79 73 74 65 |de contr|ol syste|
|000016f0| 6d 0a 0a 53 6f 6d 65 20 | 6f 66 20 74 68 65 73 65 |m..Some |of these|
|00001700| 20 6f 62 6a 65 63 74 73 | 20 61 72 65 20 72 65 70 | objects| are rep|
|00001710| 72 65 73 65 6e 74 65 64 | 20 69 6e 20 74 68 65 20 |resented| in the |
|00001720| 6e 61 6d 65 20 73 70 61 | 63 65 20 61 73 20 61 20 |name spa|ce as a |
|00001730| 64 69 72 65 63 74 6f 72 | 79 0a 77 69 74 68 20 61 |director|y.with a|
|00001740| 75 78 69 6c 69 61 72 79 | 20 69 6e 66 6f 72 6d 61 |uxiliary| informa|
|00001750| 74 69 6f 6e 2c 20 6d 6f | 75 6e 74 20 70 6f 69 6e |tion, mo|unt poin|
|00001760| 74 73 20 6f 72 20 66 69 | 6c 65 73 20 73 74 6f 72 |ts or fi|les stor|
|00001770| 65 64 20 75 6e 64 65 72 | 6e 65 61 74 68 2e 0a 54 |ed under|neath..T|
|00001780| 68 69 73 20 73 75 62 73 | 75 6d 65 73 20 6d 75 63 |his subs|umes muc|
|00001790| 68 20 6f 66 20 74 68 65 | 20 75 73 65 20 6f 66 20 |h of the| use of |
|000017a0| 73 70 65 63 69 61 6c 20 | 66 69 6c 65 73 20 6c 69 |special |files li|
|000017b0| 6b 65 20 2f 65 74 63 2f | 70 61 73 73 77 64 2c 0a |ke /etc/|passwd,.|
|000017c0| 2f 65 74 63 2f 73 65 72 | 76 69 63 65 73 20 61 6e |/etc/ser|vices an|
|000017d0| 64 20 74 68 65 20 6c 69 | 6b 65 20 69 6e 20 74 72 |d the li|ke in tr|
|000017e0| 61 64 69 74 69 6f 6e 61 | 6c 20 55 6e 69 78 2e 20 |aditiona|l Unix. |
|000017f0| 20 50 72 6f 63 65 73 73 | 65 73 20 61 72 65 20 6e | Process|es are n|
|00001800| 6f 74 0a 63 75 72 72 65 | 6e 74 6c 79 20 69 6e 20 |ot.curre|ntly in |
|00001810| 74 68 65 20 6e 61 6d 65 | 20 73 70 61 63 65 2c 20 |the name| space, |
|00001820| 62 75 74 20 74 68 65 79 | 20 77 69 6c 6c 2f 73 68 |but they| will/sh|
|00001830| 6f 75 6c 64 20 62 65 2e | 20 20 28 4a 75 73 74 20 |ould be.| (Just |
|00001840| 61 20 22 73 69 6d 70 6c | 65 0a 6d 61 74 74 65 72 |a "simpl|e.matter|
|00001850| 20 6f 66 20 70 72 6f 67 | 72 61 6d 6d 69 6e 67 2e | of prog|ramming.|
|00001860| 22 29 0a 0a 46 6f 72 20 | 65 78 61 6d 70 6c 65 20 |")..For |example |
|00001870| 2f 2d 2f 63 6f 6d 2f 64 | 65 63 2f 73 72 63 2f 75 |/-/com/d|ec/src/u|
|00001880| 73 65 72 2f 73 77 61 72 | 74 2f 68 6f 6d 65 2f 2e |ser/swar|t/home/.|
|00001890| 64 72 61 66 74 2f 36 2e | 64 72 61 66 74 20 69 73 |draft/6.|draft is|
|000018a0| 20 74 68 65 20 6e 61 6d | 65 0a 6f 66 20 74 68 65 | the nam|e.of the|
|000018b0| 20 66 69 6c 65 20 49 20 | 61 6d 20 63 75 72 72 65 | file I |am curre|
|000018c0| 6e 74 6c 79 20 74 79 70 | 69 6e 67 2c 20 2f 2d 2f |ntly typ|ing, /-/|
|000018d0| 63 6f 6d 2f 64 65 63 2f | 73 72 63 2f 75 73 65 72 |com/dec/|src/user|
|000018e0| 2f 73 77 61 72 74 2f 73 | 68 65 6c 6c 0a 69 73 20 |/swart/s|hell.is |
|000018f0| 61 20 73 79 6d 62 6f 6c | 69 63 20 6c 69 6e 6b 20 |a symbol|ic link |
|00001900| 74 6f 20 6d 79 20 73 68 | 65 6c 6c 2c 20 2f 2d 2f |to my sh|ell, /-/|
|00001910| 63 6f 6d 2f 64 65 63 2f | 70 72 6c 2f 70 65 72 6c |com/dec/|prl/perl|
|00001920| 65 2f 6e 66 73 2f 62 69 | 6e 2f 6c 73 20 69 73 0a |e/nfs/bi|n/ls is.|
|00001930| 74 68 65 20 6e 61 6d 65 | 20 6f 66 20 74 68 65 20 |the name| of the |
|00001940| 22 6c 73 22 20 70 72 6f | 67 72 61 6d 20 6f 6e 20 |"ls" pro|gram on |
|00001950| 61 20 76 61 6e 69 6c 6c | 61 20 55 6c 74 72 69 78 |a vanill|a Ultrix|
|00001960| 20 6d 61 63 68 69 6e 65 | 20 61 74 20 44 45 43 27 | machine| at DEC'|
|00001970| 73 20 50 61 72 69 73 0a | 52 65 73 65 61 72 63 68 |s Paris.|Research|
|00001980| 20 4c 61 62 2e 2e 0a 0a | 5b 59 65 73 2c 20 49 20 | Lab....|[Yes, I |
|00001990| 6b 6e 6f 77 20 77 65 20 | 61 72 65 20 75 73 69 6e |know we |are usin|
|000019a0| 67 20 22 2f 2d 2f 22 20 | 61 73 20 74 68 65 20 6e |g "/-/" |as the n|
|000019b0| 61 6d 65 20 6f 66 20 74 | 68 65 20 73 75 70 65 72 |ame of t|he super|
|000019c0| 20 72 6f 6f 74 20 61 6e | 64 20 6e 6f 74 0a 65 69 | root an|d not.ei|
|000019d0| 74 68 65 72 20 22 2f 2e | 2e 2f 22 20 6f 72 20 22 |ther "/.|./" or "|
|000019e0| 2f 2f 22 20 61 73 20 50 | 4f 53 49 58 20 6d 61 6e |//" as P|OSIX man|
|000019f0| 64 61 74 65 73 2c 20 62 | 75 74 20 74 68 6f 73 65 |dates, b|ut those|
|00001a00| 20 6f 74 68 65 72 20 73 | 74 72 69 6e 67 73 20 61 | other s|trings a|
|00001a10| 72 65 0a 73 6f 20 75 68 | 68 67 6c 79 20 61 6e 64 |re.so uh|hgly and|
|00001a20| 20 2f 2e 2e 2f 20 69 73 | 20 65 73 70 65 63 69 61 | /../ is| especia|
|00001a30| 6c 6c 79 20 6d 69 73 6c | 65 61 64 69 6e 67 20 69 |lly misl|eading i|
|00001a40| 6e 20 61 20 73 79 73 74 | 65 6d 20 77 69 74 68 20 |n a syst|em with |
|00001a50| 6d 75 6c 74 69 70 6c 65 | 0a 6c 65 76 65 6c 73 20 |multiple|.levels |
|00001a60| 6f 66 20 73 75 70 65 72 | 20 72 6f 6f 74 2c 20 65 |of super| root, e|
|00001a70| 2e 67 2e 20 6f 6e 20 6d | 79 20 6d 61 63 68 69 6e |.g. on m|y machin|
|00001a80| 65 20 22 63 64 20 2f 3b | 20 70 77 64 22 20 74 79 |e "cd /;| pwd" ty|
|00001a90| 70 65 73 0a 2f 2d 2f 63 | 6f 6d 2f 64 65 63 2f 73 |pes./-/c|om/dec/s|
|00001aa0| 72 63 2e 5d 0a 0a 54 68 | 69 6e 67 73 20 74 68 61 |rc.]..Th|ings tha|
|00001ab0| 74 20 77 65 20 64 6f 6e | 27 74 20 70 75 74 20 69 |t we don|'t put i|
|00001ac0| 6e 20 74 68 65 20 6e 61 | 6d 65 20 73 70 61 63 65 |n the na|me space|
|00001ad0| 20 61 72 65 20 6f 62 6a | 65 63 74 73 20 74 68 61 | are obj|ects tha|
|00001ae0| 74 20 61 72 65 20 70 61 | 73 73 65 64 0a 77 69 74 |t are pa|ssed.wit|
|00001af0| 68 69 6e 20 6f 72 20 62 | 65 74 77 65 65 6e 20 70 |hin or b|etween p|
|00001b00| 72 6f 63 65 73 73 65 73 | 20 62 79 20 27 68 61 6e |rocesses| by 'han|
|00001b10| 64 6c 65 27 20 72 61 74 | 68 65 72 20 74 68 61 6e |dle' rat|her than|
|00001b20| 20 62 79 20 6e 61 6d 65 | 2e 20 20 46 6f 72 0a 65 | by name|. For.e|
|00001b30| 78 61 6d 70 6c 65 2c 20 | 70 69 70 65 73 20 63 72 |xample, |pipes cr|
|00001b40| 65 61 74 65 64 20 77 69 | 74 68 20 74 68 65 20 70 |eated wi|th the p|
|00001b50| 69 70 65 28 32 29 20 63 | 61 6c 6c 2c 20 6e 65 65 |ipe(2) c|all, nee|
|00001b60| 64 20 6e 6f 74 20 62 65 | 20 69 6e 20 74 68 65 20 |d not be| in the |
|00001b70| 6e 61 6d 65 0a 73 70 61 | 63 65 2e 20 20 5b 41 74 |name.spa|ce. [At|
|00001b80| 20 61 20 66 75 72 74 68 | 65 72 20 65 78 74 72 65 | a furth|er extre|
|00001b90| 6d 65 2c 20 70 69 70 65 | 73 20 66 6f 72 20 69 6e |me, pipe|s for in|
|00001ba0| 74 72 61 2d 70 72 6f 63 | 65 73 73 20 63 6f 6d 6d |tra-proc|ess comm|
|00001bb0| 75 6e 69 63 61 74 69 6f | 6e 0a 64 6f 6e 27 74 20 |unicatio|n.don't |
|00001bc0| 65 76 65 6e 20 69 6e 76 | 6f 6c 76 65 20 63 61 6c |even inv|olve cal|
|00001bd0| 6c 69 6e 67 20 74 68 65 | 20 6b 65 72 6e 65 6c 2e |ling the| kernel.|
|00001be0| 5d 0a 0a 49 20 70 65 72 | 73 6f 6e 61 6c 6c 79 20 |]..I per|sonally |
|00001bf0| 64 6f 6e 27 74 20 62 65 | 6c 69 65 76 65 20 69 6e |don't be|lieve in|
|00001c00| 20 6f 76 65 72 6c 6f 61 | 64 69 6e 67 20 66 69 6c | overloa|ding fil|
|00001c10| 65 20 73 79 73 74 65 6d | 20 6f 70 65 72 61 74 69 |e system| operati|
|00001c20| 6f 6e 73 20 6f 6e 0a 6f | 62 6a 65 63 74 73 20 66 |ons on.o|bjects f|
|00001c30| 6f 72 20 77 68 69 63 68 | 20 74 68 65 20 6d 65 61 |or which| the mea|
|00001c40| 6e 69 6e 67 20 69 73 20 | 74 65 6e 75 6f 75 73 20 |ning is |tenuous |
|00001c50| 28 65 2e 67 2e 20 22 75 | 6e 6c 69 6e 6b 22 20 3d |(e.g. "u|nlink" =|
|00001c60| 3e 20 22 6b 69 6c 6c 20 | 2d 54 45 52 4d 22 0a 6f |> "kill |-TERM".o|
|00001c70| 6e 20 6f 62 6a 65 63 74 | 73 20 6f 66 20 74 79 70 |n object|s of typ|
|00001c80| 65 20 70 72 6f 63 65 73 | 73 29 3b 20 77 65 20 74 |e proces|s); we t|
|00001c90| 65 6e 64 20 74 6f 20 64 | 65 66 69 6e 65 20 6e 65 |end to d|efine ne|
|00001ca0| 77 20 6f 70 65 72 61 74 | 69 6f 6e 73 20 66 6f 72 |w operat|ions for|
|00001cb0| 0a 6d 61 6e 69 70 75 6c | 61 74 69 6e 67 20 6f 62 |.manipul|ating ob|
|00001cc0| 6a 65 63 74 73 20 6f 66 | 20 61 20 6e 65 77 20 74 |jects of| a new t|
|00001cd0| 79 70 65 2e 20 20 42 75 | 74 20 74 68 61 74 20 69 |ype. Bu|t that i|
|00001ce0| 73 20 65 76 65 6e 20 6d | 6f 72 65 20 6f 66 20 61 |s even m|ore of a|
|00001cf0| 0a 64 69 67 72 65 73 73 | 69 6f 6e 20 74 68 61 6e |.digress|ion than|
|00001d00| 20 49 20 77 61 6e 74 65 | 64 20 74 6f 20 67 65 74 | I wante|d to get|
|00001d10| 20 69 6e 74 6f 21 0a 0a | 53 6f 72 72 79 20 66 6f | into!..|Sorry fo|
|00001d20| 72 20 74 68 65 20 6c 65 | 6e 67 74 68 20 6f 66 20 |r the le|ngth of |
|00001d30| 74 68 69 73 20 6d 65 73 | 73 61 67 65 2c 20 49 20 |this mes|sage, I |
|00001d40| 73 65 65 6d 20 74 6f 20 | 68 61 76 65 20 67 6f 74 |seem to |have got|
|00001d50| 74 65 6e 20 63 61 72 72 | 69 65 64 0a 61 77 61 79 |ten carr|ied.away|
|00001d60| 2e 0a 0a 48 61 70 70 79 | 20 74 72 61 69 6c 73 2c |...Happy| trails,|
|00001d70| 0a 0a 47 61 72 72 65 74 | 20 53 77 61 72 74 0a 44 |..Garret| Swart.D|
|00001d80| 45 43 20 53 79 73 74 65 | 6d 73 20 52 65 73 65 61 |EC Syste|ms Resea|
|00001d90| 72 63 68 20 43 65 6e 74 | 65 72 0a 31 33 30 20 4c |rch Cent|er.130 L|
|00001da0| 79 74 74 6f 6e 20 41 76 | 65 6e 75 65 0a 50 61 6c |ytton Av|enue.Pal|
|00001db0| 6f 20 41 6c 74 6f 2c 20 | 43 41 20 39 34 33 30 31 |o Alto, |CA 94301|
|00001dc0| 0a 28 34 31 35 29 20 38 | 35 33 2d 32 32 32 30 0a |.(415) 8|53-2220.|
|00001dd0| 64 65 63 77 72 6c 21 73 | 77 61 72 74 2e 55 55 43 |decwrl!s|wart.UUC|
|00001de0| 50 20 6f 72 20 73 77 61 | 72 74 40 73 72 63 2e 64 |P or swa|rt@src.d|
|00001df0| 65 63 2e 63 6f 6d 0a 0a | 56 6f 6c 75 6d 65 2d 4e |ec.com..|Volume-N|
|00001e00| 75 6d 62 65 72 3a 20 56 | 6f 6c 75 6d 65 20 32 31 |umber: V|olume 21|
|00001e10| 2c 20 4e 75 6d 62 65 72 | 20 39 31 0a 0a |, Number| 91.. |
+--------+-------------------------+-------------------------+--------+--------+