/ Usenet 1994 January / usenetsourcesnewsgroupsinfomagicjanuary1994.iso / sources / std_unix / v22 / 060

< prev

next >

MacOS 8.1

Win98

DOS

browse contents

view JSON data

view as text

+--------+-------------------------+-------------------------+--------+--------+
|00000000| 46 72 6f 6d 20 6a 73 71 | 40 63 73 2e 75 74 65 78 |From jsq|@cs.utex|
|00000010| 61 73 2e 65 64 75 20 20 | 46 72 69 20 4a 61 6e 20 |as.edu  |Fri Jan |
|00000020| 20 34 20 31 39 3a 31 34 | 3a 32 31 20 31 39 39 31 | 4 19:14|:21 1991|
|00000030| 0a 52 65 63 65 69 76 65 | 64 3a 20 66 72 6f 6d 20 |.Receive|d: from |
|00000040| 43 53 2e 55 54 45 58 41 | 53 2e 45 44 55 20 62 79 |CS.UTEXA|S.EDU by|
|00000050| 20 75 75 6e 65 74 2e 55 | 55 2e 4e 45 54 20 28 35 | uunet.U|U.NET (5|
|00000060| 2e 36 31 2f 31 2e 31 34 | 29 20 77 69 74 68 20 53 |.61/1.14|) with S|
|00000070| 4d 54 50 20 0a 09 69 64 | 20 41 41 32 35 39 33 39 |MTP ..id| AA25939|
|00000080| 3b 20 46 72 69 2c 20 34 | 20 4a 61 6e 20 39 31 20 |; Fri, 4| Jan 91 |
|00000090| 31 39 3a 31 34 3a 32 31 | 20 2d 30 35 30 30 0a 50 |19:14:21| -0500.P|
|000000a0| 6f 73 74 65 64 2d 44 61 | 74 65 3a 20 34 20 4a 61 |osted-Da|te: 4 Ja|
|000000b0| 6e 20 39 31 20 31 38 3a | 32 36 3a 33 34 20 47 4d |n 91 18:|26:34 GM|
|000000c0| 54 0a 52 65 63 65 69 76 | 65 64 3a 20 62 79 20 63 |T.Receiv|ed: by c|
|000000d0| 73 2e 75 74 65 78 61 73 | 2e 65 64 75 20 28 35 2e |s.utexas|.edu (5.|
|000000e0| 36 34 2f 31 2e 39 32 29 | 20 0a 46 72 6f 6d 3a 20 |64/1.92)| .From: |
|000000f0| 64 6f 6d 6f 40 74 73 61 | 2e 63 6f 2e 75 6b 20 28 |domo@tsa|.co.uk (|
|00000100| 44 6f 6d 69 6e 69 63 20 | 44 75 6e 6c 6f 70 29 0a |Dominic |Dunlop).|
|00000110| 4e 65 77 73 67 72 6f 75 | 70 73 3a 20 63 6f 6d 70 |Newsgrou|ps: comp|
|00000120| 2e 73 74 64 2e 75 6e 69 | 78 0a 53 75 62 6a 65 63 |.std.uni|x.Subjec|
|00000130| 74 3a 20 52 65 3a 20 71 | 66 6f 72 6b 28 29 0a 4d |t: Re: q|fork().M|
|00000140| 65 73 73 61 67 65 2d 49 | 64 3a 20 3c 31 36 35 32 |essage-I|d: <1652|
|00000150| 32 40 63 73 2e 75 74 65 | 78 61 73 2e 65 64 75 3e |2@cs.ute|xas.edu>|
|00000160| 0a 52 65 66 65 72 65 6e | 63 65 73 3a 20 3c 31 36 |.Referen|ces: <16|
|00000170| 32 31 33 40 63 73 2e 75 | 74 65 78 61 73 2e 65 64 |213@cs.u|texas.ed|
|00000180| 75 3e 20 3c 31 36 34 38 | 33 40 63 73 2e 75 74 65 |u> <1648|3@cs.ute|
|00000190| 78 61 73 2e 65 64 75 3e | 0a 53 65 6e 64 65 72 3a |xas.edu>|.Sender:|
|000001a0| 20 6a 73 71 40 63 73 2e | 75 74 65 78 61 73 2e 65 | jsq@cs.|utexas.e|
|000001b0| 64 75 0a 52 65 70 6c 79 | 2d 54 6f 3a 20 64 6f 6d |du.Reply|-To: dom|
|000001c0| 6f 40 74 73 61 2e 63 6f | 2e 75 6b 0a 4f 72 67 61 |o@tsa.co|.uk.Orga|
|000001d0| 6e 69 7a 61 74 69 6f 6e | 3a 20 54 68 65 20 53 74 |nization|: The St|
|000001e0| 61 6e 64 61 72 64 20 41 | 6e 73 77 65 72 20 4c 74 |andard A|nswer Lt|
|000001f0| 64 2e 0a 58 2d 53 75 62 | 6d 69 73 73 69 6f 6e 73 |d..X-Sub|missions|
|00000200| 3a 20 73 74 64 2d 75 6e | 69 78 40 75 75 6e 65 74 |: std-un|ix@uunet|
|00000210| 2e 75 75 2e 6e 65 74 0a | 44 61 74 65 3a 20 34 20 |.uu.net.|Date: 4 |
|00000220| 4a 61 6e 20 39 31 20 31 | 38 3a 32 36 3a 33 34 20 |Jan 91 1|8:26:34 |
|00000230| 47 4d 54 0a 54 6f 3a 20 | 73 74 64 2d 75 6e 69 78 |GMT.To: |std-unix|
|00000240| 40 75 75 6e 65 74 2e 55 | 55 2e 4e 45 54 0a 0a 53 |@uunet.U|U.NET..S|
|00000250| 75 62 6d 69 74 74 65 64 | 2d 62 79 3a 20 64 6f 6d |ubmitted|-by: dom|
|00000260| 6f 40 74 73 61 2e 63 6f | 2e 75 6b 20 28 44 6f 6d |o@tsa.co|.uk (Dom|
|00000270| 69 6e 69 63 20 44 75 6e | 6c 6f 70 29 0a 0a 49 6e |inic Dun|lop)..In|
|00000280| 20 61 72 74 69 63 6c 65 | 20 3c 31 36 34 38 33 40 | article| <16483@|
|00000290| 63 73 2e 75 74 65 78 61 | 73 2e 65 64 75 3e 20 6c |cs.utexa|s.edu> l|
|000002a0| 65 77 69 6e 65 40 64 67 | 2e 75 75 63 70 20 28 44 |ewine@dg|.uucp (D|
|000002b0| 6f 6e 61 6c 64 20 4c 65 | 77 69 6e 65 29 20 77 72 |onald Le|wine) wr|
|000002c0| 69 74 65 73 3a 0a 0a 3e | 20 09 49 20 74 68 69 6e |ites:..>| .I thin|
|000002d0| 6b 20 49 20 77 6f 75 6c | 64 20 76 6f 74 65 20 22 |k I woul|d vote "|
|000002e0| 4e 4f 22 20 6f 6e 20 71 | 66 6f 72 6b 28 29 2e 20 |NO" on q|fork(). |
|000002f0| 20 49 20 74 68 69 6e 6b | 20 74 68 61 74 20 74 68 | I think| that th|
|00000300| 65 72 65 20 61 72 65 20 | 0a 3e 20 09 74 77 6f 20 |ere are |.> .two |
|00000310| 62 65 74 74 65 72 20 73 | 6f 6c 75 74 69 6f 6e 73 |better s|olutions|
|00000320| 3a 0a 3e 20 09 28 31 29 | 20 4a 75 73 74 20 75 73 |:.> .(1)| Just us|
|00000330| 65 20 66 6f 72 6b 28 29 | 20 61 6e 64 20 72 65 71 |e fork()| and req|
|00000340| 75 69 72 65 20 74 68 65 | 20 69 6d 70 6c 65 6d 65 |uire the| impleme|
|00000350| 6e 74 61 74 69 6f 6e 20 | 74 6f 20 64 6f 20 69 74 |ntation |to do it|
|00000360| 0a 3e 20 20 20 20 20 20 | 20 20 20 69 6e 20 61 6e |.>      |   in an|
|00000370| 20 65 66 66 69 63 69 65 | 6e 74 20 6d 61 6e 6e 65 | efficie|nt manne|
|00000380| 72 2e 0a 0a 57 65 6c 6c | 2c 20 49 20 6b 6e 6f 77 |r...Well|, I know|
|00000390| 20 74 68 61 74 20 77 65 | 20 50 4f 53 49 58 20 66 | that we| POSIX f|
|000003a0| 6f 6c 6b 73 20 77 61 6e | 74 20 74 6f 20 72 75 6c |olks wan|t to rul|
|000003b0| 65 20 74 68 65 20 77 6f | 72 6c 64 2c 20 62 75 74 |e the wo|rld, but|
|000003c0| 20 6a 75 73 74 20 68 6f | 77 0a 75 67 6c 79 20 61 | just ho|w.ugly a|
|000003d0| 20 77 6f 72 6c 64 20 77 | 69 6c 6c 20 77 65 20 70 | world w|ill we p|
|000003e0| 75 74 20 75 70 20 77 69 | 74 68 20 69 6e 20 6f 72 |ut up wi|th in or|
|000003f0| 64 65 72 20 74 68 61 74 | 20 77 65 20 63 61 6e 20 |der that| we can |
|00000400| 72 75 6c 65 20 69 74 3f | 20 20 71 66 6f 72 6b 28 |rule it?|  qfork(|
|00000410| 29 0a 28 61 6e 64 20 76 | 66 6f 72 6b 28 29 29 20 |).(and v|fork()) |
|00000420| 73 70 65 63 69 61 6c 2d | 63 61 73 65 20 61 20 70 |special-|case a p|
|00000430| 61 72 74 69 63 75 6c 61 | 72 20 75 73 61 67 65 20 |articula|r usage |
|00000440| 6f 66 20 74 68 65 20 70 | 72 6f 63 65 73 73 20 63 |of the p|rocess c|
|00000450| 72 65 61 74 69 6f 6e 0a | 6d 65 63 68 61 6e 69 73 |reation.|mechanis|
|00000460| 6d 20 69 6e 20 6f 72 64 | 65 72 20 74 6f 20 67 69 |m in ord|er to gi|
|00000470| 76 65 20 69 6d 70 6c 65 | 6d 65 6e 74 6f 72 73 20 |ve imple|mentors |
|00000480| 61 6e 20 65 61 73 69 65 | 72 20 74 69 6d 65 20 6f |an easie|r time o|
|00000490| 66 20 69 74 2e 20 20 42 | 79 20 6e 6f 77 20 77 65 |f it.  B|y now we|
|000004a0| 0a 6b 6e 6f 77 20 74 68 | 61 74 20 69 6e 20 61 20 |.know th|at in a |
|000004b0| 60 60 66 72 6f 6d 20 74 | 6f 20 67 72 6f 75 6e 64 |``from t|o ground|
|000004c0| 20 75 70 27 27 20 76 69 | 72 74 75 61 6c 20 6d 65 | up'' vi|rtual me|
|000004d0| 6d 6f 72 79 20 69 6d 70 | 6c 65 6d 65 6e 74 61 74 |mory imp|lementat|
|000004e0| 69 6f 6e 20 6f 66 0a 55 | 4e 49 2a 58 20 77 69 74 |ion of.U|NI*X wit|
|000004f0| 68 20 61 20 68 61 6c 66 | 2d 77 61 79 20 75 73 65 |h a half|-way use|
|00000500| 66 75 6c 20 6d 65 6d 6f | 72 79 20 6d 61 6e 61 67 |ful memo|ry manag|
|00000510| 65 6d 65 6e 74 20 68 61 | 72 64 77 61 72 65 20 63 |ement ha|rdware c|
|00000520| 6f 70 79 20 6f 6e 20 77 | 72 69 74 65 20 61 6e 64 |opy on w|rite and|
|00000530| 0a 73 69 6d 69 6c 61 72 | 20 66 69 6e 65 73 73 69 |.similar| finessi|
|00000540| 6e 67 20 63 61 6e 20 6d | 61 6b 65 20 74 68 65 20 |ng can m|ake the |
|00000550| 67 65 6e 65 72 61 6c 2d | 63 61 73 65 20 66 6f 72 |general-|case for|
|00000560| 6b 28 29 20 63 61 6c 6c | 20 61 73 20 65 66 66 69 |k() call| as effi|
|00000570| 63 69 65 6e 74 20 61 73 | 0a 61 6e 79 20 73 70 65 |cient as|.any spe|
|00000580| 63 69 61 6c 2d 63 61 73 | 65 20 76 61 72 69 61 6e |cial-cas|e varian|
|00000590| 74 2c 20 61 6e 64 2c 20 | 75 6e 6c 69 6b 65 20 74 |t, and, |unlike t|
|000005a0| 68 65 20 76 61 72 69 61 | 6e 74 73 2c 20 69 73 20 |he varia|nts, is |
|000005b0| 66 72 65 65 20 66 72 6f | 6d 20 61 6e 79 0a 74 68 |free fro|m any.th|
|000005c0| 72 65 61 74 20 74 68 61 | 74 20 73 69 78 74 65 65 |reat tha|t sixtee|
|000005d0| 6e 20 74 6f 6e 20 77 65 | 69 67 68 74 73 20 77 69 |n ton we|ights wi|
|000005e0| 6c 6c 20 62 65 20 64 72 | 6f 70 70 65 64 20 6f 6e |ll be dr|opped on|
|000005f0| 20 61 6e 79 20 70 72 6f | 67 72 61 6d 6d 65 72 20 | any pro|grammer |
|00000600| 77 68 6f 0a 73 74 65 70 | 73 20 6f 75 74 20 6f 66 |who.step|s out of|
|00000610| 20 6c 69 6e 65 2e 0a 0a | 54 68 61 74 20 73 61 69 | line...|That sai|
|00000620| 64 2c 20 50 4f 53 49 58 | 20 68 61 73 20 6e 6f 74 |d, POSIX| has not|
|00000630| 68 69 6e 67 20 74 6f 20 | 73 61 79 20 61 62 6f 75 |hing to |say abou|
|00000640| 74 20 74 68 65 20 65 66 | 66 69 63 69 65 6e 63 79 |t the ef|ficiency|
|00000650| 20 6f 66 20 61 6e 79 0a | 70 61 72 74 69 63 75 6c | of any.|particul|
|00000660| 61 72 20 69 6d 70 6c 65 | 6d 65 6e 74 61 74 69 6f |ar imple|mentatio|
|00000670| 6e 3a 20 74 68 61 74 27 | 73 20 61 20 71 75 61 6c |n: that'|s a qual|
|00000680| 69 74 79 20 69 73 73 75 | 65 2c 20 6e 6f 74 20 61 |ity issu|e, not a|
|00000690| 20 63 6f 6e 66 6f 72 6d | 61 6e 63 65 0a 69 73 73 | conform|ance.iss|
|000006a0| 75 65 2e 20 20 4f 6e 65 | 20 68 6f 70 65 73 20 74 |ue.  One| hopes t|
|000006b0| 68 61 74 20 69 6e 20 74 | 68 65 20 6b 69 6e 64 20 |hat in t|he kind |
|000006c0| 6f 66 20 66 72 65 65 20 | 6d 61 72 6b 65 74 20 74 |of free |market t|
|000006d0| 68 61 74 20 73 74 61 6e | 64 61 72 64 73 20 61 72 |hat stan|dards ar|
|000006e0| 65 0a 73 75 70 70 6f 73 | 65 64 20 74 6f 20 65 6e |e.suppos|ed to en|
|000006f0| 63 6f 75 72 61 67 65 2c | 20 62 65 74 74 65 72 20 |courage,| better |
|00000700| 71 75 61 6c 69 74 79 20 | 77 69 6c 6c 20 77 69 6e |quality |will win|
|00000710| 20 6f 75 74 20 6f 76 65 | 72 20 70 6f 6f 72 65 72 | out ove|r poorer|
|00000720| 20 71 75 61 6c 69 74 79 | 2c 0a 6f 74 68 65 72 20 | quality|,.other |
|00000730| 74 68 69 6e 67 73 20 62 | 65 69 6e 67 20 65 71 75 |things b|eing equ|
|00000740| 61 6c 2e 20 20 53 6f 2c | 20 79 65 73 2c 20 49 27 |al.  So,| yes, I'|
|00000750| 6d 20 69 6e 20 66 61 76 | 6f 75 72 20 6f 66 20 6b |m in fav|our of k|
|00000760| 65 65 70 69 6e 67 20 6a | 75 73 74 0a 66 6f 72 6b |eeping j|ust.fork|
|00000770| 28 29 2c 20 61 6e 64 20 | 6c 65 74 74 69 6e 67 20 |(), and |letting |
|00000780| 69 6d 70 6c 65 6d 65 6e | 74 6f 72 73 20 77 6f 72 |implemen|tors wor|
|00000790| 72 79 20 61 62 6f 75 74 | 20 68 6f 77 20 73 6c 69 |ry about| how sli|
|000007a0| 63 6b 20 74 68 65 79 20 | 6e 65 65 64 20 74 6f 20 |ck they |need to |
|000007b0| 6d 61 6b 65 0a 69 74 2e | 20 20 41 66 74 65 72 20 |make.it.|  After |
|000007c0| 61 6c 6c 2c 20 74 68 65 | 72 65 27 73 20 66 65 77 |all, the|re's few|
|000007d0| 20 69 6d 70 6c 65 6d 65 | 6e 74 6f 72 73 20 69 6e | impleme|ntors in|
|000007e0| 20 74 68 69 73 20 77 6f | 72 6c 64 20 74 68 61 6e | this wo|rld than|
|000007f0| 20 61 70 70 6c 69 63 61 | 74 69 6f 6e 73 0a 70 72 | applica|tions.pr|
|00000800| 6f 67 72 61 6d 6d 65 72 | 73 2c 20 73 6f 20 69 74 |ogrammer|s, so it|
|00000810| 20 73 65 65 6d 73 20 74 | 6f 20 6d 61 6b 65 20 73 | seems t|o make s|
|00000820| 65 6e 73 65 20 74 6f 20 | 6c 6f 63 61 6c 69 7a 65 |ense to |localize|
|00000830| 20 74 68 65 20 70 61 69 | 6e 20 69 6e 76 6f 6c 76 | the pai|n involv|
|00000840| 65 64 20 74 6f 0a 74 68 | 65 20 73 6d 61 6c 6c 65 |ed to.th|e smalle|
|00000850| 72 20 67 72 6f 75 70 2e | 20 20 53 6f 72 72 79 20 |r group.|  Sorry |
|00000860| 61 62 6f 75 74 20 74 68 | 61 74 2e 20 20 49 20 61 |about th|at.  I a|
|00000870| 6d 20 61 77 61 72 65 20 | 74 68 61 74 20 74 68 65 |m aware |that the|
|00000880| 20 65 66 66 69 63 69 65 | 6e 74 0a 69 6d 70 6c 65 | efficie|nt.imple|
|00000890| 6d 65 6e 74 61 74 69 6f | 6e 20 6f 66 20 66 6f 72 |mentatio|n of for|
|000008a0| 6b 28 29 20 69 73 20 61 | 20 72 65 61 6c 20 68 65 |k() is a| real he|
|000008b0| 61 64 61 63 68 65 20 6f | 6e 20 73 6f 6d 65 20 61 |adache o|n some a|
|000008c0| 72 63 68 69 74 65 63 74 | 75 72 65 73 2c 20 61 6e |rchitect|ures, an|
|000008d0| 64 0a 70 61 72 74 69 63 | 75 6c 61 72 6c 79 20 69 |d.partic|ularly i|
|000008e0| 6e 20 68 6f 73 74 65 64 | 20 50 4f 53 49 58 2c 20 |n hosted| POSIX, |
|000008f0| 62 75 74 2c 20 77 65 6c | 6c 2c 20 73 6f 27 73 20 |but, wel|l, so's |
|00000900| 63 6f 6f 6b 69 6e 67 20 | 75 70 20 66 61 6b 65 20 |cooking |up fake |
|00000910| 69 6e 6f 64 65 73 0a 28 | 6f 72 20 70 61 72 74 73 |inodes.(|or parts|
|00000920| 20 74 68 65 72 65 6f 66 | 29 2e 20 20 48 61 70 70 | thereof|).  Happ|
|00000930| 69 6c 79 2c 20 49 20 68 | 65 61 72 20 6e 6f 62 6f |ily, I h|ear nobo|
|00000940| 64 79 20 73 75 67 67 65 | 73 74 69 6e 67 20 74 68 |dy sugge|sting th|
|00000950| 61 74 20 77 65 20 64 65 | 66 69 6e 65 0a 75 6e 73 |at we de|fine.uns|
|00000960| 61 66 65 20 76 65 72 73 | 69 6f 6e 73 20 6f 66 20 |afe vers|ions of |
|00000970| 73 74 61 74 28 29 20 74 | 6f 20 67 65 74 20 61 72 |stat() t|o get ar|
|00000980| 6f 75 6e 64 20 74 68 61 | 74 20 70 72 6f 62 6c 65 |ound tha|t proble|
|00000990| 6d 2e 20 20 4a 75 73 74 | 20 68 6f 77 20 66 61 72 |m.  Just| how far|
|000009a0| 0a 73 68 6f 75 6c 64 20 | 77 65 20 62 65 6e 64 20 |.should |we bend |
|000009b0| 6f 76 65 72 20 62 61 63 | 6b 77 61 72 64 73 20 74 |over bac|kwards t|
|000009c0| 6f 20 61 63 63 6f 6d 6d | 6f 64 61 74 65 20 68 69 |o accomm|odate hi|
|000009d0| 73 74 6f 72 79 3f 20 20 | 52 65 6d 65 6d 62 65 72 |story?  |Remember|
|000009e0| 20 74 68 61 74 0a 65 76 | 65 72 79 20 65 78 74 72 | that.ev|ery extr|
|000009f0| 61 20 66 75 6e 63 74 69 | 6f 6e 20 77 65 20 64 65 |a functi|on we de|
|00000a00| 66 69 6e 65 20 68 61 73 | 20 74 6f 20 62 65 20 6d |fine has| to be m|
|00000a10| 61 69 6e 74 61 69 6e 65 | 64 20 6f 6e 20 61 6c 6c |aintaine|d on all|
|00000a20| 0a 69 6d 70 6c 65 6d 65 | 6e 74 61 74 69 6f 6e 73 |.impleme|ntations|
|00000a30| 20 66 6f 72 20 65 76 65 | 72 20 6d 6f 72 65 20 28 | for eve|r more (|
|00000a40| 6d 6f 72 65 20 6f 72 20 | 6c 65 73 73 29 2c 20 61 |more or |less), a|
|00000a50| 6e 64 20 74 68 61 74 20 | 65 76 65 72 79 20 65 78 |nd that |every ex|
|00000a60| 74 72 61 0a 66 75 6e 63 | 74 69 6f 6e 20 69 73 20 |tra.func|tion is |
|00000a70| 73 6f 6d 65 74 68 69 6e | 67 20 65 6c 73 65 20 74 |somethin|g else t|
|00000a80| 68 61 74 20 70 72 6f 67 | 72 61 6d 6d 65 72 73 20 |hat prog|rammers |
|00000a90| 68 61 76 65 20 74 6f 20 | 6c 65 61 72 6e 20 61 62 |have to |learn ab|
|00000aa0| 6f 75 74 2e 0a 0a 3e 20 | 20 20 20 20 28 32 29 20 |out...> |    (2) |
|00000ab0| 41 64 64 20 73 6f 6d 65 | 20 6e 65 77 20 66 75 6e |Add some| new fun|
|00000ac0| 63 74 69 6f 6e 73 20 28 | 66 65 78 65 63 28 29 20 |ctions (|fexec() |
|00000ad0| 3f 29 20 77 68 69 63 68 | 20 64 6f 20 74 68 65 20 |?) which| do the |
|00000ae0| 66 6f 72 6b 28 29 20 61 | 6e 64 0a 3e 20 20 20 20 |fork() a|nd.>    |
|00000af0| 20 20 20 20 20 65 78 65 | 63 28 29 20 69 6e 20 6f |     exe|c() in o|
|00000b00| 6e 65 20 63 61 6c 6c 2e | 20 20 49 20 6b 6e 6f 77 |ne call.|  I know|
|00000b10| 20 74 68 61 74 20 74 68 | 69 73 20 69 73 20 6e 6f | that th|is is no|
|00000b20| 74 20 65 78 69 73 74 69 | 6e 67 20 70 72 61 63 74 |t existi|ng pract|
|00000b30| 69 63 65 0a 3e 20 20 20 | 20 20 20 20 20 20 62 75 |ice.>   |      bu|
|00000b40| 74 20 6e 65 69 74 68 65 | 72 20 77 61 73 20 73 69 |t neithe|r was si|
|00000b50| 67 65 6d 70 74 79 73 65 | 74 28 29 20 6f 72 20 74 |gemptyse|t() or t|
|00000b60| 63 67 65 74 69 73 70 65 | 65 64 28 29 2e 20 20 54 |cgetispe|ed().  T|
|00000b70| 68 69 73 20 6d 61 79 20 | 62 65 0a 3e 20 20 20 20 |his may |be.>    |
|00000b80| 20 20 20 20 20 61 6e 6f | 74 68 65 72 20 63 61 73 |     ano|ther cas|
|00000b90| 65 20 77 68 65 72 65 20 | 69 74 20 69 73 20 62 65 |e where |it is be|
|00000ba0| 74 74 65 72 20 74 6f 20 | 64 65 66 69 6e 65 20 61 |tter to |define a|
|00000bb0| 20 6e 65 77 20 69 6e 74 | 65 72 66 61 63 65 20 74 | new int|erface t|
|00000bc0| 68 61 6e 0a 3e 20 20 20 | 20 20 20 20 20 20 74 6f |han.>   |      to|
|00000bd0| 20 74 72 79 20 74 6f 20 | 64 65 73 63 72 69 62 65 | try to |describe|
|00000be0| 20 74 68 65 20 65 78 69 | 73 74 69 6e 67 20 70 72 | the exi|sting pr|
|00000bf0| 61 63 74 69 63 65 2e 20 | 20 5b 5b 41 6c 73 6f 2c |actice. | [[Also,|
|00000c00| 20 71 66 6f 72 6b 28 29 | 20 69 73 0a 3e 20 20 20 | qfork()| is.>   |
|00000c10| 20 20 20 20 20 20 6e 6f | 74 20 71 75 69 74 65 20 |      no|t quite |
|00000c20| 76 66 6f 72 6b 28 29 20 | 73 6f 20 69 74 20 63 61 |vfork() |so it ca|
|00000c30| 6e 20 62 65 20 73 68 6f | 74 20 64 6f 77 6e 20 6f |n be sho|t down o|
|00000c40| 6e 20 74 68 65 20 73 61 | 6d 65 20 62 61 73 69 73 |n the sa|me basis|
|00000c50| 2e 5d 5d 0a 0a 49 20 64 | 6f 6e 27 74 20 6c 69 6b |.]]..I d|on't lik|
|00000c60| 65 20 74 68 69 73 20 6d | 75 63 68 20 65 69 74 68 |e this m|uch eith|
|00000c70| 65 72 2c 20 62 75 74 20 | 69 74 20 6d 69 67 68 74 |er, but |it might|
|00000c80| 20 62 65 20 61 6e 20 61 | 63 63 65 70 74 61 62 6c | be an a|cceptabl|
|00000c90| 65 20 63 6f 6d 70 72 6f | 6d 69 73 65 0a 69 66 20 |e compro|mise.if |
|00000ca0| 74 68 65 20 65 66 66 65 | 63 74 20 6f 66 20 74 68 |the effe|ct of th|
|00000cb0| 65 20 6e 65 77 20 66 75 | 6e 63 74 69 6f 6e 73 20 |e new fu|nctions |
|00000cc0| 77 61 73 20 64 65 66 69 | 6e 65 64 20 69 6e 20 74 |was defi|ned in t|
|00000cd0| 68 65 20 73 74 61 6e 64 | 61 72 64 20 69 6e 20 74 |he stand|ard in t|
|00000ce0| 65 72 6d 73 0a 6f 66 20 | 66 6f 72 6b 28 29 20 61 |erms.of |fork() a|
|00000cf0| 6e 64 20 65 78 65 63 28 | 29 20 66 61 6d 69 6c 79 |nd exec(|) family|
|00000d00| 20 66 75 6e 63 74 69 6f | 6e 73 2e 20 20 54 68 69 | functio|ns.  Thi|
|00000d10| 73 20 77 6f 75 6c 64 20 | 6d 61 6b 65 20 69 74 20 |s would |make it |
|00000d20| 65 61 73 79 20 74 6f 20 | 62 72 69 6e 67 0a 65 78 |easy to |bring.ex|
|00000d30| 69 73 74 69 6e 67 20 69 | 6d 70 6c 65 6d 65 6e 74 |isting i|mplement|
|00000d40| 61 74 69 6f 6e 73 20 77 | 69 74 68 20 61 6e 20 65 |ations w|ith an e|
|00000d50| 66 66 69 63 69 65 6e 74 | 20 66 6f 72 6b 28 29 20 |fficient| fork() |
|00000d60| 69 6e 74 6f 20 6c 69 6e | 65 2e 20 20 50 6c 65 61 |into lin|e.  Plea|
|00000d70| 73 65 0a 6c 65 74 27 73 | 20 72 65 73 69 73 74 20 |se.let's| resist |
|00000d80| 74 68 65 20 74 65 6d 70 | 74 61 74 69 6f 6e 20 74 |the temp|tation t|
|00000d90| 6f 20 61 64 64 20 6e 65 | 77 20 66 75 6e 63 74 69 |o add ne|w functi|
|00000da0| 6f 6e 61 6c 69 74 79 20 | 74 6f 20 65 78 65 63 20 |onality |to exec |
|00000db0| 28 66 6f 72 0a 65 78 61 | 6d 70 6c 65 29 20 6f 6e |(for.exa|mple) on|
|00000dc0| 20 74 68 65 20 77 61 79 | 20 70 61 73 74 2e 0a 0a | the way| past...|
|00000dd0| 42 79 20 74 68 65 20 77 | 61 79 2c 20 77 68 61 74 |By the w|ay, what|
|00000de0| 20 6c 69 6e 65 20 28 69 | 66 20 61 6e 79 29 20 61 | line (i|f any) a|
|00000df0| 72 65 20 74 68 65 20 2e | 35 20 28 41 64 61 29 20 |re the .|5 (Ada) |
|00000e00| 66 6f 6c 6b 73 20 74 61 | 6b 69 6e 67 20 6f 6e 20 |folks ta|king on |
|00000e10| 74 68 69 73 0a 69 73 73 | 75 65 3f 20 20 48 6f 77 |this.iss|ue?  How|
|00000e20| 20 64 6f 65 73 20 61 6c | 6c 20 74 68 69 73 20 73 | does al|l this s|
|00000e30| 71 75 61 72 65 20 28 69 | 66 20 61 74 20 61 6c 6c |quare (i|f at all|
|00000e40| 29 20 77 69 74 68 20 41 | 64 61 27 73 20 63 6f 6e |) with A|da's con|
|00000e50| 63 65 70 74 20 6f 66 20 | 61 0a 74 61 73 6b 3f 0a |cept of |a.task?.|
|00000e60| 2d 2d 20 0a 44 6f 6d 69 | 6e 69 63 20 44 75 6e 6c |-- .Domi|nic Dunl|
|00000e70| 6f 70 0a 0a 56 6f 6c 75 | 6d 65 2d 4e 75 6d 62 65 |op..Volu|me-Numbe|
|00000e80| 72 3a 20 56 6f 6c 75 6d | 65 20 32 32 2c 20 4e 75 |r: Volum|e 22, Nu|
|00000e90| 6d 62 65 72 20 36 30 0a | 0a                      |mber 60.|.       |
+--------+-------------------------+-------------------------+--------+--------+