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+( Any)1 224(executed commands.)1 839 2 720 2508 t
+10 CW f
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+10 I f
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+( the braces:)2 454( Without)1 378(will wait an hour in the background, then print a message.)10 2319 3 720 3374 t
+9 CW f
+(sleep 3600;echo 'Time''s up!'&)3 1620 1 1008 3544 t
+10 R f
+(this would lock up the terminal for an hour, then print the message in the background!)15 3440 1 720 3724 t
+10 B f
+( flow \320)2 333(12. Control)1 508 2 720 3964 t
+10 CW f
+(for)1586 3964 w
+10 R f
+(A command may be executed once for each member of a list by typing, for example:)15 3387 1 720 4120 t
+9 CW f
+(for\(i in printf scanf putchar\) look $i /usr/td/lib/dw.dat)7 3078 1 1008 4290 t
+10 R f
+(This looks for each of the words)6 1292 1 720 4470 t
+10 CW f
+(printf)2037 4470 w
+10 R f
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+(scanf)2447 4470 w
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+9 CW f
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+(command)1527 4990 w
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+( example:)1 391( For)1 189(also provides a general if-statement.)4 1444 3 850 5686 t
+9 CW f
+(if\(cyntax *.c\) cc -g -o cmd *.c)6 1674 1 1008 5856 t
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+(cyntax)2018 6036 w
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+( `if not' statement provides a)5 1226(. An)1 211 2 3603 6036 t
+( example:)1 391( For)1 189(two-tailed conditional.)1 905 3 720 6156 t
+9 CW f
+(for\(i\){)1008 6326 w
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+(if not cp $i /tmp)4 918 1 1224 6546 t
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+%%EndPage: 4 4
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+5 pagesetup
+10 R f
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+10 I f
+(Rc)720 996 w
+10 R f
+('s while statement looks like this:)5 1342 1 825 996 t
+9 CW f
+(while\(newer subr.c subr.o\) sleep 5)4 1836 1 1008 1166 t
+10 R f
+(This waits until)2 623 1 720 1346 t
+10 CW f
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+10 CW f
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+(\(presumably because the C compiler finished with it.\))7 2147 1 2695 1346 t
+10 B f
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+10 CW f
+(switch)1586 1586 w
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+(for filename matching, except that)4 1372 1 720 2872 t
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+( to the next case \(or the end of the switch\) are)11 1864(If any pattern matches, the commands following that case up)9 2456 2 720 3028 t
+( example,)1 388( For)1 189(executed, and execution of the switch is complete.)7 2010 3 720 3148 t
+9 CW f
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+(case 2)1 324 1 1008 3648 t
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+( other number elicits a usage message.)6 1533( Any)1 222(is appended to the second.)4 1051 3 720 4388 t
+(The built-in)1 475 1 720 4544 t
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+( sets)1 181( It)1 118(string and a list of patterns.)5 1123 3 720 4664 t
+10 CW f
+($status)2173 4664 w
+10 R f
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+(The following example processes option arguments for the)7 2349 1 720 4784 t
+10 I f
+(man)3094 4784 w
+10 R f
+(\(1\) command:)1 563 1 3266 4784 t
+9 CW f
+(opt=\(\))1008 4954 w
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+%%EndPage: 5 5
+%%Page: 6 6
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+mark
+6 pagesetup
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+10 R f
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+9 CW f
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+(name)1170 1166 w
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+(name)2550 1346 w
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+( to)1 106(ment list will assigned)3 910 2 720 1466 t
+10 CW f
+($*)1764 1466 w
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+(and)1912 1466 w
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+( value of)2 355(. The)1 233 2 3288 1466 t
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+($*)3904 1466 w
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+(will be restored on com-)4 988 1 4052 1466 t
+( example:)1 391(pletion. For)1 492 2 720 1586 t
+9 CW f
+(fn g {)2 324 1 1008 1756 t
+(gre -e $1 *.[hcyl])3 972 1 1224 1866 t
+(})1008 1976 w
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+(defines)720 2156 w
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+(pattern)2487 2156 w
+10 R f
+(in all program source files in the current directory.)8 2015 1 2801 2156 t
+(Function definitions are deleted by writing)5 1707 1 720 2312 t
+9 CW f
+(fn)1008 2482 w
+9 I f
+(name)1170 2482 w
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+(with no function body.)3 911 1 720 2662 t
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+10 R f
+( very little about what)4 897(Up to now we've said)4 892 2 720 3058 t
+10 I f
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+10 R f
+( the command name)3 822( If)1 121(does to execute a simple command.)5 1445 3 2652 3058 t
+(is the name of a function defined using)7 1570 1 720 3178 t
+10 CW f
+(fn)2317 3178 w
+10 R f
+( if it is the name of a built-)8 1082( Otherwise,)1 487(, the function is executed.)4 1034 3 2437 3178 t
+(in command, the built-in is executed directly by)7 1964 1 720 3298 t
+10 I f
+(rc)2716 3298 w
+10 R f
+( if the name contains a)5 936(. Otherwise,)1 517 2 2799 3298 t
+10 CW f
+(/)4284 3298 w
+10 R f
+(, it is taken to be)5 696 1 4344 3298 t
+(the name of a binary program and is executed using)9 2155 1 720 3418 t
+10 I f
+(exec)2910 3418 w
+10 R f
+( the name contains no)4 907(\(2\). If)1 267 2 3086 3418 t
+10 CW f
+(/)4294 3418 w
+10 R f
+(, then directories)2 686 1 4354 3418 t
+(mentioned in the variable)3 1018 1 720 3538 t
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+($path)1763 3538 w
+10 R f
+(are searched until an executable file is found.)7 1806 1 2088 3538 t
+10 B f
+( commands)1 486(18. Built-in)1 504 2 720 3778 t
+10 R f
+( executed internally by)3 924(Several commands are)2 909 2 720 3934 t
+10 I f
+(rc)2582 3934 w
+10 R f
+(because they are difficult or impossible to implement oth-)8 2346 1 2694 3934 t
+(erwise.)720 4054 w
+10 CW f
+(. [-i])1 360 1 720 4210 t
+10 I f
+(file ...)1 228 1 1140 4210 t
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+(Execute commands from)2 1008 1 970 4330 t
+10 I f
+(file)2008 4330 w
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+(.)2136 4330 w
+10 CW f
+($*)2216 4330 w
+10 R f
+( reminder of the argument list follow-)6 1545(is set for the duration to the)6 1129 2 2366 4330 t
+(ing)970 4450 w
+10 I f
+(file)1125 4450 w
+10 R f
+(.)1253 4450 w
+10 CW f
+($path)1330 4450 w
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+10 I f
+(file)2490 4450 w
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+(. Option)1 354 1 2618 4450 t
+10 CW f
+(-i)2998 4450 w
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+(indicates interactive input)2 1034 1 3144 4450 t
+10 S f
+(-)4204 4450 w
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+(a prompt \(found in)3 755 1 4285 4450 t
+10 CW f
+($prompt)970 4570 w
+10 R f
+(\) is printed before each command is read.)7 1651 1 1390 4570 t
+10 CW f
+(builtin)720 4726 w
+10 I f
+(command ...)1 488 1 1200 4726 t
+10 R f
+(Execute)970 4846 w
+10 I f
+(command)1316 4846 w
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+(as usual except that any function named)6 1597 1 1729 4846 t
+10 I f
+(command)3351 4846 w
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+( example,)1 388( For)1 189(is ignored.)1 422 3 3764 4846 t
+9 CW f
+(fn cd{)1 324 1 1258 5016 t
+(builtin cd $* && pwd)4 1080 1 1474 5126 t
+(})1258 5236 w
+10 R f
+(defines a replacement for the)4 1177 1 970 5416 t
+10 CW f
+(cd)2177 5416 w
+10 R f
+(built-in \(see below\) that announces the full name of the new direc-)11 2713 1 2327 5416 t
+(tory.)970 5536 w
+10 CW f
+(cd [)1 240 1 720 5692 t
+10 I f
+(dir)960 5692 w
+10 CW f
+(])1077 5692 w
+10 R f
+(Change the current directory to)4 1255 1 970 5812 t
+10 I f
+(dir)2252 5812 w
+10 R f
+( default argument is)3 802(. The)1 232 2 2369 5812 t
+10 CW f
+($home)3430 5812 w
+10 R f
+(.)3730 5812 w
+10 CW f
+($cdpath)3808 5812 w
+10 R f
+(is a list of places in)5 784 1 4256 5812 t
+(which to search for)3 767 1 970 5932 t
+10 I f
+(dir)1762 5932 w
+10 R f
+(.)1879 5932 w
+10 CW f
+(eval [)1 360 1 720 6088 t
+10 I f
+(arg ...)1 239 1 1080 6088 t
+10 CW f
+(])1319 6088 w
+10 R f
+(The arguments are catenated separated by spaces into a string, read as input to)13 3159 1 970 6208 t
+10 I f
+(rc)4158 6208 w
+10 R f
+( For)1 193(, and executed.)2 606 2 4241 6208 t
+(example,)970 6328 w
+9 CW f
+(x='$y')1258 6498 w
+(y=Doody)1258 6608 w
+(eval echo Howdy, $x)3 1026 1 1258 6718 t
+10 R f
+(would echo)1 463 1 970 6898 t
+9 CW f
+(Howdy, Doody)1 648 1 1258 7068 t
+10 R f
+(since the arguments of)3 901 1 970 7248 t
+10 CW f
+(eval)1896 7248 w
+10 R f
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+cleartomark
+showpage
+saveobj restore
+%%EndPage: 6 6
+%%Page: 7 7
+/saveobj save def
+mark
+7 pagesetup
+10 R f
+(- 7 -)2 166 1 2797 480 t
+9 CW f
+(echo Howdy, $y)2 756 1 1258 830 t
+10 R f
+(after substituting for)2 816 1 970 1010 t
+10 CW f
+($x)1811 1010 w
+10 R f
+(.)1931 1010 w
+10 CW f
+(shift [)1 420 1 720 1166 t
+10 I f
+(n)1140 1166 w
+10 CW f
+(])1190 1166 w
+10 R f
+(Delete the first)2 593 1 970 1286 t
+10 I f
+(n)1588 1286 w
+10 R f
+(\(default 1\) elements of)3 906 1 1663 1286 t
+10 CW f
+($*)2594 1286 w
+10 R f
+(.)2714 1286 w
+10 CW f
+(wait [)1 360 1 720 1442 t
+10 I f
+(pid)1080 1442 w
+10 CW f
+(])1208 1442 w
+10 R f
+( given)1 263(Wait for the process with the)5 1231 2 970 1562 t
+10 I f
+(pid)2505 1562 w
+10 R f
+( no)1 141( If)1 132(to exit.)1 294 3 2674 1562 t
+10 I f
+(pid)3282 1562 w
+10 R f
+(is given, all outstanding processes are)5 1589 1 3451 1562 t
+(waited for.)1 432 1 970 1682 t
+10 CW f
+(whatis)720 1838 w
+10 I f
+(name ...)1 316 1 1140 1838 t
+10 R f
+( each)1 209(Print the value of)3 694 2 970 1958 t
+10 I f
+(name)1900 1958 w
+10 R f
+(in a form suitable for input to)6 1189 1 2143 1958 t
+10 I f
+(rc)3359 1958 w
+10 R f
+( output is an assignment to a vari-)7 1366(. The)1 232 2 3442 1958 t
+(able, the definition of a function, a call to)8 1709 1 970 2078 t
+10 CW f
+(builtin)2711 2078 w
+10 R f
+( the path name of a)5 792(for a built-in command, or)4 1085 2 3163 2078 t
+( example,)1 388( For)1 189(binary program.)1 643 3 970 2198 t
+9 CW f
+(whatis path g cd who)4 1080 1 1258 2368 t
+10 R f
+(might print)1 448 1 970 2548 t
+9 CW f
+(path=\(. /bin /usr/bin\))2 1188 1 1258 2718 t
+(fn g {gre -e $1 *.[hycl]})5 1350 1 1258 2828 t
+(builtin cd)1 540 1 1258 2938 t
+(/bin/who)1258 3048 w
+10 CW f
+(\304)720 3264 w
+10 I f
+(subject pattern ...)2 697 1 840 3264 t
+10 R f
+(The)970 3384 w
+10 I f
+(subject)1150 3384 w
+10 R f
+(is matched against each)3 945 1 1458 3384 t
+10 I f
+(pattern)2428 3384 w
+10 R f
+( a match,)2 365( On)1 172(in turn.)1 289 3 2742 3384 t
+10 CW f
+($status)3594 3384 w
+10 R f
+( Otherwise,)1 486(is set to true.)3 514 2 4040 3384 t
+(it is set to)3 396 1 970 3504 t
+10 CW f
+('no match')1 602 1 1393 3504 t
+10 R f
+( The)1 207( are the same as for filename matching.)7 1582(. Patterns)1 399 3 1995 3504 t
+10 I f
+(patterns)4210 3504 w
+10 R f
+(are not sub-)2 475 1 4565 3504 t
+(jected to filename replacement before the)5 1698 1 970 3624 t
+10 CW f
+(\304)2702 3624 w
+10 R f
+(command is executed, so they need not be enclosed in)9 2244 1 2796 3624 t
+(quotation marks, unless of course, a literal match for)8 2102 1 970 3744 t
+10 CW f
+(* [)1 145 1 3097 3744 t
+10 R f
+(or)3267 3744 w
+10 CW f
+(?)3375 3744 w
+10 R f
+( example)1 363( For)1 189(is required.)1 449 3 3485 3744 t
+9 CW f
+(\304 $1 ?)2 324 1 1258 3914 t
+10 R f
+(matches any single character, whereas)4 1525 1 970 4094 t
+9 CW f
+(\304 $1 '?')2 432 1 1258 4264 t
+10 R f
+(only matches a literal question mark.)5 1476 1 970 4444 t
+10 B f
+( I/O Redirection)2 694(19. Advanced)1 603 2 720 4684 t
+10 I f
+(Rc)720 4840 w
+10 R f
+( of file descriptors other than 0 and 1 \(standard input and output\) by specifying the file)16 3472(allows redirection)1 718 2 850 4840 t
+(descriptor in square brackets)3 1144 1 720 4960 t
+10 CW f
+([ ])1 180 1 1889 4960 t
+10 R f
+(after the)1 329 1 2094 4960 t
+10 CW f
+(<)2448 4960 w
+10 R f
+(or)2533 4960 w
+10 CW f
+(>)2641 4960 w
+10 R f
+( example,)1 388(. For)1 214 2 2701 4960 t
+9 CW f
+(cc junk.c >[2]junk.diag)2 1242 1 1008 5130 t
+10 R f
+(saves the compiler's diagnostics in)4 1393 1 720 5310 t
+10 CW f
+(junk.diag)2138 5310 w
+10 R f
+(.)2678 5310 w
+( replaced by a copy, in the sense of)8 1471(File descriptors may be)3 959 2 720 5466 t
+10 I f
+(dup)3184 5466 w
+10 R f
+(\(2\), of an already-open file by typing, for)7 1706 1 3334 5466 t
+(example)720 5586 w
+9 CW f
+(cc junk.c >[2=1])2 864 1 1008 5756 t
+10 R f
+( in conjunction with other)4 1061( is more useful)3 609( It)1 117(This replaces file descriptor 2 with a copy of file descriptor 1.)11 2533 4 720 5936 t
+(redirections, like this)2 841 1 720 6056 t
+9 CW f
+(cc junk.c >junk.out >[2=1])3 1404 1 1008 6226 t
+10 R f
+( descriptor 1 to)3 629(Redirections are evaluated from left to right, so this redirects file)10 2667 2 720 6406 t
+10 CW f
+(junk.out)4050 6406 w
+10 R f
+(, then points)2 510 1 4530 6406 t
+( contrast,)1 366( By)1 167(file descriptor 2 at the same file.)6 1289 3 720 6526 t
+9 CW f
+(cc junk.c >[2=1] >junk.out)3 1404 1 1008 6696 t
+10 R f
+( \(presumably the terminal\), and then directs file)7 2000(Redirects file descriptor 2 to a copy of file descriptor 1)10 2320 2 720 6876 t
+( the first case, standard and diagnostic output will be intermixed in)11 2686( In)1 135( at a file.)3 355(descriptor 1)1 477 4 720 6996 t
+10 CW f
+(junk.out)4400 6996 w
+10 R f
+(. In)1 160 1 4880 6996 t
+(the second, diagnostic output will appear on the terminal, and standard output will be sent to the file.)17 4024 1 720 7116 t
+( For)1 211( using the duplication notation with an empty right-hand side.)9 2664(File descriptors may be closed by)5 1445 3 720 7272 t
+cleartomark
+showpage
+saveobj restore
+%%EndPage: 7 7
+%%Page: 8 8
+/saveobj save def
+mark
+8 pagesetup
+10 R f
+(- 8 -)2 166 1 2797 480 t
+(example,)720 840 w
+9 CW f
+(cc junk.c >[2=])2 810 1 1008 1010 t
+10 R f
+(will discard diagnostics from the compilation.)5 1838 1 720 1190 t
+(Arbitrary file descriptors may be sent through a pipe by typing, for example)12 3031 1 720 1346 t
+9 CW f
+(cc junk.c |[2] grep -v '\303$')5 1458 1 1008 1516 t
+10 R f
+( that the output of)4 779( Note)1 261( the C compiler's output.)4 1065(This deletes those ever-so-annoying blank lines from)6 2215 4 720 1696 t
+10 CW f
+(grep)720 1816 w
+10 R f
+(still appears on file descriptor 1.)5 1287 1 985 1816 t
+( a pipe to some file descriptor other than zero.)9 1871(Very occasionally you may wish to connect the input side of)10 2449 2 720 1972 t
+(The notation)1 508 1 720 2092 t
+9 CW f
+(cmd1 |[5=19] cmd2)2 918 1 1008 2262 t
+10 R f
+(creates a pipeline with)3 895 1 720 2442 t
+10 CW f
+(cmd1)1640 2442 w
+10 R f
+('s file descriptor 5 connected through a pipe to)8 1863 1 1880 2442 t
+10 CW f
+(cmd2)3768 2442 w
+10 R f
+('s file descriptor 19.)3 804 1 4008 2442 t
+10 B f
+( documents)1 486(20. Here)1 385 2 720 2682 t
+10 I f
+(Rc)720 2838 w
+10 R f
+( to commands, as in this)5 982(procedures may include data, called ``here documents'', to be provided as input)11 3206 2 852 2838 t
+(version of the)2 549 1 720 2958 t
+10 I f
+(tel)1294 2958 w
+10 R f
+(command)1419 2958 w
+9 CW f
+(for\(i\) grep $i <<!)3 972 1 1008 3128 t
+(...)1008 3238 w
+(nls 2T-402 2912)2 810 1 1008 3348 t
+(norman 2C-514 2842)2 972 1 1008 3458 t
+(pjw 2T-502 7214)2 810 1 1008 3568 t
+(...)1008 3678 w
+(!)1008 3788 w
+10 R f
+(A here document is introduced by the redirection symbol)8 2288 1 720 3968 t
+10 CW f
+(<<)3034 3968 w
+10 R f
+( by an arbitrary eof marker \()6 1141(, followed)1 406 2 3154 3968 t
+10 CW f
+(!)4701 3968 w
+10 R f
+(in the)1 227 1 4813 3968 t
+( to a line containing only the eof marker are saved in a tempo-)13 2507( following the command, up)4 1142(example\). Lines)1 671 3 720 4088 t
+(rary file that it connected to the command's standard input when it is run.)13 2935 1 720 4208 t
+10 I f
+(Rc)720 4364 w
+10 R f
+( following)1 414( The)1 205(does variable substitution in here documents.)5 1804 3 850 4364 t
+10 I f
+(subst)3298 4364 w
+10 R f
+(command:)3529 4364 w
+9 CW f
+(ed $3 <<EOF)2 594 1 1008 4534 t
+(g/$1/s//$2/g)1008 4644 w
+(w)1008 4754 w
+(EOF)1008 4864 w
+10 R f
+( of)1 113(changes all occurrences)2 954 2 720 5044 t
+10 CW f
+($1)1817 5044 w
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+10 CW f
+($2)2075 5044 w
+10 R f
+(in file)1 241 1 2225 5044 t
+10 CW f
+($3)2496 5044 w
+10 R f
+( include a literal)3 661(. To)1 191 2 2616 5044 t
+10 CW f
+($)3498 5044 w
+10 R f
+(in a here document, type)4 1004 1 3588 5044 t
+10 CW f
+($$)4622 5044 w
+10 R f
+( the)1 152(. If)1 146 2 4742 5044 t
+(name of a variable is followed immediately by)7 1861 1 720 5164 t
+10 CW f
+(\303)2606 5164 w
+10 R f
+(, the caret is deleted.)4 820 1 2666 5164 t
+( by enclosing the eof marker following)6 1643(Variable substitution can be entirely suppressed)5 1981 2 720 5320 t
+10 CW f
+(<<)4384 5320 w
+10 R f
+(in quotation)1 496 1 4544 5320 t
+(marks.)720 5440 w
+(Here documents may be provided on file descriptors other than 0 by typing, for example)14 3530 1 720 5596 t
+9 CW f
+(cmd <<[4]End)1 648 1 1008 5766 t
+(...)1008 5876 w
+(End)1008 5986 w
+10 B f
+(21. Signals)1 482 1 720 6286 t
+10 I f
+(Rc)720 6442 w
+10 R f
+( function with the name of)5 1067( A)1 124( an interrupt is received from the terminal.)7 1705(scripts normally terminate when)3 1293 4 851 6442 t
+( the usual way, but called when)6 1268(a signal, in lower case, is defined in)7 1449 2 720 6562 t
+10 I f
+(rc)3464 6562 w
+10 R f
+( of inter-)2 353( Signals)1 347(receives the signal.)2 766 3 3574 6562 t
+(est are:)1 285 1 720 6682 t
+10 CW f
+(sighup)720 6838 w
+10 R f
+( controlling teletype has disconnected from)5 1728(Hangup. The)1 546 2 970 6958 t
+10 I f
+(rc)3269 6958 w
+10 R f
+(.)3352 6958 w
+10 CW f
+(sigint)720 7114 w
+10 R f
+(The interrupt character \(usually ASCII del\) was typed on the controlling terminal.)11 3272 1 970 7234 t
+cleartomark
+showpage
+saveobj restore
+%%EndPage: 8 8
+%%Page: 9 9
+/saveobj save def
+mark
+9 pagesetup
+10 R f
+(- 9 -)2 166 1 2797 480 t
+10 CW f
+(sigquit)720 840 w
+10 R f
+(The quit character \(usually ASCII fs, ctrl-\\\) was typed on the controlling terminal.)12 3278 1 970 960 t
+10 CW f
+(sigterm)720 1116 w
+10 R f
+(This signal is normally sent by)5 1231 1 970 1236 t
+10 I f
+(kill)2226 1236 w
+10 R f
+(\(1\).)2354 1236 w
+10 CW f
+(sigexit)720 1392 w
+10 R f
+(An artificial signal sent when)4 1176 1 970 1512 t
+10 I f
+(rc)2171 1512 w
+10 R f
+(is about to exit.)3 617 1 2279 1512 t
+(As an example,)2 618 1 720 1668 t
+9 CW f
+(fn sigint{)1 540 1 1008 1838 t
+(rm /tmp/junk)1 648 1 1224 1948 t
+(exit)1224 2058 w
+(})1008 2168 w
+10 R f
+(sets a trap for the keyboard interrupt that removes a temporary file before exiting.)13 3259 1 720 2348 t
+( routine is set to)4 651(Signals will be ignored if the signal)6 1434 2 720 2504 t
+10 CW f
+({})2833 2504 w
+10 R f
+( revert to their default behavior when their)7 1714(. Signals)1 373 2 2953 2504 t
+(handlers' definitions are deleted.)3 1308 1 720 2624 t
+10 B f
+(22. Environment)1 742 1 720 2864 t
+10 R f
+( Plan 9, the environ-)4 817( On)1 173( is a list of name-value pairs made available to executing binaries.)11 2645(The environment)1 685 4 720 3020 t
+( in a file system named)5 929(ment is stored)2 565 2 720 3140 t
+10 CW f
+(#e)2240 3140 w
+10 R f
+(, normally mounted on)3 914 1 2360 3140 t
+10 CW f
+(/env)3300 3140 w
+10 R f
+( value of each variable is stored)6 1269(. The)1 231 2 3540 3140 t
+( is not quite as horrendous as it sounds,)8 1577( \(This)1 262(in a separate file, with components terminated by ASCII nuls.)9 2481 3 720 3260 t
+( contents of)2 482( The)1 213( access is involved.\))3 828(the file system is maintained entirely in core, so no disk or network)12 2797 4 720 3380 t
+10 CW f
+(/env)720 3500 w
+10 R f
+(are shared on a per-process group basis)6 1579 1 987 3500 t
+10 S f
+(-)2593 3500 w
+10 R f
+( process group is created it effectively attaches)7 1885(when a new)2 480 2 2675 3500 t
+10 CW f
+(/env)720 3620 w
+10 R f
+( consequence of this organization is that)6 1603( A)1 122(to a new file system initialized with a copy of the old one.)12 2329 3 986 3620 t
+(commands can change environment entries and see the changes reflected in)10 3014 1 720 3740 t
+10 I f
+(rc)3759 3740 w
+10 R f
+(.)3842 3740 w
+( in the environment, although this could easily)7 1939(There is not currently a way on Plan 9 to place functions)11 2381 2 720 3896 t
+(done by mounting another instance of)5 1537 1 720 4016 t
+10 CW f
+(#e)2287 4016 w
+10 R f
+( can be)2 290( problem is that currently there)5 1259( The)1 210(on another directory.)2 844 4 2437 4016 t
+(only one instance of)3 807 1 720 4136 t
+10 CW f
+(#e)1552 4136 w
+10 R f
+(per process group.)2 734 1 1697 4136 t
+10 B f
+( Variables)1 436(23. Local)1 414 2 720 4376 t
+10 R f
+( assignment followed by a com-)5 1289( An)1 174( the duration of a single command.)6 1402(It is often useful to set a variable for)8 1455 4 720 4532 t
+( example)1 363( For)1 189(mand has this effect.)3 826 3 720 4652 t
+9 CW f
+(a=global)1008 4822 w
+(a=local echo $a)2 810 1 1008 4932 t
+(echo $a)1 378 1 1008 5042 t
+10 R f
+(will print)1 370 1 720 5222 t
+9 CW f
+(local)1008 5392 w
+(global)1008 5502 w
+10 R f
+(This works even for compound commands, like)6 1906 1 720 5682 t
+9 CW f
+(f=/fairly/long/file/name {)1 1404 1 1008 5852 t
+({ wc $f; spell $f; diff $f.old $f } |)9 1998 1 1224 5962 t
+(pr -h 'Facts about '$f | lp -ddp)7 1728 1 1332 6072 t
+(})1008 6182 w
+10 B f
+( \320)1 125(24. Examples)1 592 2 720 6482 t
+10 I f
+(cd, pwd)1 311 1 1462 6482 t
+10 R f
+(Here is a pair of functions that provide enhanced versions of the standard)12 2933 1 720 6638 t
+10 CW f
+(cd)3679 6638 w
+10 R f
+(and)3825 6638 w
+10 CW f
+(pwd)3996 6638 w
+10 R f
+(commands. \(Thanks)1 837 1 4203 6638 t
+(to Rob Pike for these.\))4 902 1 720 6758 t
+cleartomark
+showpage
+saveobj restore
+%%EndPage: 9 9
+%%Page: 10 10
+/saveobj save def
+mark
+10 pagesetup
+10 R f
+(- 10 -)2 216 1 2772 480 t
+9 CW f
+( default prompt)2 810( #)1 486(ps1='% ')1 432 3 1008 830 t
+( a tab character)3 864( #)1 432(tab=' ')1 486 3 1008 940 t
+(fn pbd{)1 378 1 1008 1050 t
+(/bin/pwd|sed 's;.*/;;')1 1188 1 1116 1160 t
+(})1008 1270 w
+(fn cd{)1 324 1 1008 1380 t
+(builtin cd $1 &&)3 864 1 1116 1490 t
+(switch\($#*\){)1116 1600 w
+(case 0)1 324 1 1116 1710 t
+(dir=$home)1224 1820 w
+(prompt=\($ps1 $tab\))1 972 1 1224 1930 t
+(case *)1 324 1 1116 2040 t
+(switch\($1\))1224 2150 w
+(case /*)1 378 1 1224 2260 t
+(dir=$1)1332 2370 w
+(prompt=\(`{pbd}\303$ps1 $tab\))1 1350 1 1332 2480 t
+(case */* ..*)2 648 1 1224 2590 t
+(dir=\(\))1332 2700 w
+(prompt=\(`{pbd}\303$ps1 $tab\))1 1350 1 1332 2810 t
+(case *)1 324 1 1224 2920 t
+(dir=\(\))1332 3030 w
+(prompt=\($1\303$ps1 $tab\))1 1134 1 1332 3140 t
+(})1224 3250 w
+(})1116 3360 w
+(})1008 3470 w
+(fn pwd{)1 378 1 1008 3580 t
+(if\(\304 $#dir 0\))2 702 1 1116 3690 t
+(dir=`{/bin/pwd})1224 3800 w
+(echo $dir)1 486 1 1116 3910 t
+(})1008 4020 w
+10 R f
+(Function)720 4200 w
+10 CW f
+(pwd)1104 4200 w
+10 R f
+(is a version of the standard)5 1088 1 1312 4200 t
+10 CW f
+(pwd)2428 4200 w
+10 R f
+(that caches its value in variable)5 1270 1 2636 4200 t
+10 CW f
+($dir)3935 4200 w
+10 R f
+(, because the genuine)3 865 1 4175 4200 t
+10 CW f
+(pwd)720 4320 w
+10 R f
+(can be quite slow to execute.)5 1153 1 925 4320 t
+(Function)720 4476 w
+10 CW f
+(pbd)1114 4476 w
+10 R f
+( Function)1 419(is a helper that prints the last component of a directory name.)11 2589 2 1332 4476 t
+10 CW f
+(cd)4378 4476 w
+10 R f
+(calls the)1 344 1 4537 4476 t
+10 CW f
+(cd)4920 4476 w
+10 R f
+( so, it sets)3 404( If)1 119( was successful.)2 646(built-in, and checks that it)4 1057 4 720 4596 t
+10 CW f
+($dir)2974 4596 w
+10 R f
+(and)3242 4596 w
+10 CW f
+($prompt)3414 4596 w
+10 R f
+( prompt will include the)4 973(. The)1 233 2 3834 4596 t
+(last component of the current directory \(except in the home directory, where it will be null\), and)16 3869 1 720 4716 t
+10 CW f
+($dir)4616 4716 w
+10 R f
+(will)4884 4716 w
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+10 CW f
+(\(\))2307 4836 w
+10 R f
+(, so that the)3 461 1 2427 4836 t
+10 CW f
+(pwd)2913 4836 w
+10 R f
+(function will work correctly.)3 1148 1 3118 4836 t
+10 B f
+( \320)1 125(25. Examples)1 592 2 720 5076 t
+10 I f
+(man)1462 5076 w
+10 R f
+(The)720 5232 w
+10 I f
+(man)900 5232 w
+10 R f
+( is called, for example, as)5 1017( It)1 111(command prints pages from of the Programmer's Manual.)7 2324 3 1097 5232 t
+9 CW f
+(man 3 isatty)2 648 1 1008 5402 t
+(man rc)1 324 1 1008 5512 t
+(man -t cat)2 540 1 1008 5622 t
+10 R f
+(In the first case, the page for)6 1192 1 720 5802 t
+10 I f
+(isatty)1946 5802 w
+10 R f
+( second case, the manual page for)6 1403( the)1 156( In)1 142(in section 3 is printed.)4 922 4 2197 5802 t
+10 I f
+(rc)4855 5802 w
+10 R f
+(is)4973 5802 w
+( specified, all sections are searched for the page, and it is found in sec-)14 2871( no manual section is)4 864(printed. Since)1 585 3 720 5922 t
+( the third case, the page for)6 1083( In)1 133(tion 1.)1 256 3 720 6042 t
+10 I f
+(cat)2217 6042 w
+10 R f
+(is typeset \(the)2 555 1 2364 6042 t
+10 CW f
+(-t)2944 6042 w
+10 R f
+(option\).)3089 6042 w
+cleartomark
+showpage
+saveobj restore
+%%EndPage: 10 10
+%%Page: 11 11
+/saveobj save def
+mark
+11 pagesetup
+10 R f
+(- 11 -)2 216 1 2772 480 t
+9 CW f
+(cd /n/bowell/usr/man || {)3 1350 1 1008 830 t
+(echo $0: Manual not on line! >[1=2])6 1890 1 1116 940 t
+(exit 1)1 324 1 1116 1050 t
+(})1008 1160 w
+( default nroff)2 756(NT=n #)1 378 2 1008 1270 t
+(s='*' # section, default try all)5 1728 1 1008 1380 t
+(for\(i\) switch\($i\){)1 972 1 1008 1490 t
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+(NT=t)1116 1710 w
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+(NT=n)1116 1930 w
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+(echo Usage: $0 '[-nt] [section] page ...' >[1=2])7 2592 1 1116 2150 t
+(exit 1)1 324 1 1116 2260 t
+(case [1-9] 10)2 702 1 1008 2370 t
+(s=$i)1116 2480 w
+(case *)1 324 1 1008 2590 t
+(eval 'pages=man'$s/$i'.*')1 1350 1 1116 2700 t
+(for\(page in $pages\){)2 1080 1 1116 2810 t
+(if\(test -f $page\))2 918 1 1224 2920 t
+($NT\303roff -man $page)2 1026 1 1332 3030 t
+(if not)1 324 1 1224 3140 t
+(echo $0: $i not found >[1=2])5 1512 1 1332 3250 t
+(})1116 3360 w
+(})1008 3470 w
+10 R f
+(Note the use of)3 619 1 720 3650 t
+10 CW f
+(eval)1368 3650 w
+10 R f
+( Without)1 382(to make a list of candidate manual pages.)7 1675 2 1637 3650 t
+10 CW f
+(eval)3723 3650 w
+10 R f
+(, the)1 176 1 3963 3650 t
+10 CW f
+(*)4168 3650 w
+10 R f
+(stored in)1 352 1 4258 3650 t
+10 CW f
+($s)4640 3650 w
+10 R f
+(would)4790 3650 w
+( if it weren't, it would be)6 1098(not trigger filename matching \320 it's enclosed in quotation marks, and even)11 3222 2 720 3770 t
+(expanded when assigned to)3 1098 1 720 3890 t
+10 CW f
+($s)1844 3890 w
+10 R f
+( causes its arguments to be re-processed by)7 1728(. Eval)1 259 2 1964 3890 t
+10 I f
+(rc)3977 3890 w
+10 R f
+('s parser and interpreter,)3 980 1 4060 3890 t
+(effectively delaying evaluation of the)4 1491 1 720 4010 t
+10 CW f
+(*)2236 4010 w
+10 R f
+(until the assignment to)3 909 1 2321 4010 t
+10 CW f
+($pages)3255 4010 w
+10 R f
+(.)3615 4010 w
+10 B f
+( \320)1 125(26. Examples)1 592 2 720 4250 t
+10 I f
+(holmdel)1462 4250 w
+10 R f
+(The following)1 575 1 720 4406 t
+10 I f
+(rc)1327 4406 w
+10 R f
+(script plays the deceptively simple game)5 1658 1 1442 4406 t
+10 I f
+(holmdel)3132 4406 w
+10 R f
+(, in which the players alternately name)6 1586 1 3454 4406 t
+(Bell Labs locations, the winner being the first to mention Holmdel.)10 2682 1 720 4526 t
+(This script is worth describing in detail \(rather, it would be if it weren't so silly.\))15 3222 1 720 4682 t
+(Variable)720 4838 w
+10 CW f
+($t)1097 4838 w
+10 R f
+( Including)1 443(is an abbreviation for the name of a temporary file.)9 2115 2 1251 4838 t
+10 CW f
+($pid)3844 4838 w
+10 R f
+(, initialized by)2 595 1 4084 4838 t
+10 I f
+(rc)4714 4838 w
+10 R f
+(to its)1 208 1 4832 4838 t
+( one)1 178(process-id, in the names of temporary files insures that their names won't collide, in case more than)16 4142 2 720 4958 t
+(instance of the script is running at a time.)8 1651 1 720 5078 t
+(Function)720 5234 w
+10 CW f
+(read)1102 5234 w
+10 R f
+( is the name of a variable into which a line gathered from standard input is read.)16 3223('s argument)1 475 2 1342 5234 t
+10 CW f
+($ifs)720 5354 w
+10 R f
+( Thus)1 252(is set to just a newline.)5 921 2 987 5354 t
+10 CW f
+(read)2187 5354 w
+10 R f
+( at spaces, but the terminating newline is)7 1633('s input is not split apart)5 980 2 2427 5354 t
+(deleted.)720 5474 w
+(A handler is set to catch)5 1012 1 720 5630 t
+10 CW f
+(sigint)1767 5630 w
+10 R f
+(,)2127 5630 w
+10 CW f
+(sigquit)2188 5630 w
+10 R f
+(, and)1 205 1 2608 5630 t
+10 CW f
+(sighup,)2849 5630 w
+10 R f
+(and the artificial)2 676 1 3305 5630 t
+10 CW f
+(sigexit)4017 5630 w
+10 R f
+( just)1 181(signal. It)1 386 2 4473 5630 t
+(removes the temporary file and exits.)5 1486 1 720 5750 t
+( file is initialized from a here document containing a list of Bell Labs locations, and the main)17 3730(The temporary)1 590 2 720 5906 t
+(loop starts.)1 439 1 720 6026 t
+( \(in)1 144(First, the program guesses a location)5 1500 2 720 6182 t
+10 CW f
+($lab)2397 6182 w
+10 R f
+(\) using the)2 438 1 2637 6182 t
+10 CW f
+(fortune)3108 6182 w
+10 R f
+(program to pick a random line from)6 1479 1 3561 6182 t
+( prints the location, and if it guessed Holmdel, prints a message and exits.)13 2942( It)1 111(the location list.)2 642 3 720 6302 t
+( the)1 149(Then it uses)2 485 2 720 6458 t
+10 CW f
+(read)1381 6458 w
+10 R f
+(function to get lines from standard input and validity-check them until it gets a legal)14 3392 1 1648 6458 t
+( that the condition part of a)6 1118(name. Note)1 491 2 720 6578 t
+10 CW f
+(while)2360 6578 w
+10 R f
+( the exit status of the)5 855( Only)1 255( compound command.)2 901(can be a)2 338 4 2691 6578 t
+(last command in the sequence is checked.)6 1666 1 720 6698 t
+( it goes back to the top of the loop.)9 1388( Otherwise)1 460(Again, if the result is Holmdel, it prints a message and exits.)11 2415 3 720 6854 t
+cleartomark
+showpage
+saveobj restore
+%%EndPage: 11 11
+%%Page: 12 12
+/saveobj save def
+mark
+12 pagesetup
+10 R f
+(- 12 -)2 216 1 2772 480 t
+9 CW f
+(t=/tmp/holmdel$pid)1008 890 w
+(fn read{)1 432 1 1008 1000 t
+($1=`{awk '{print;exit}'})1 1296 1 1440 1110 t
+(})1008 1220 w
+(ifs=')1008 1330 w
+( just a newline)3 810(' #)1 486 2 1008 1440 t
+(fn sigexit sigint sigquit sighup{)4 1782 1 1008 1550 t
+(rm -f $t)2 432 1 1440 1660 t
+(exit)1440 1770 w
+(})1008 1880 w
+(cat <<'!' >$t)2 702 1 1008 1990 t
+(Allentown)1008 2100 w
+(Atlanta)1008 2210 w
+(Cedar Crest)1 594 1 1008 2320 t
+(Chester)1008 2430 w
+(Columbus)1008 2540 w
+(Elmhurst)1008 2650 w
+(Fullerton)1008 2760 w
+(Holmdel)1008 2870 w
+(Indian Hill)1 594 1 1008 2980 t
+(Merrimack Valley)1 864 1 1008 3090 t
+(Morristown)1008 3200 w
+(Piscataway)1008 3310 w
+(Reading)1008 3420 w
+(Short Hills)1 594 1 1008 3530 t
+(South Plainfield)1 864 1 1008 3640 t
+(Summit)1008 3750 w
+(Whippany)1008 3860 w
+(West Long Branch)2 864 1 1008 3970 t
+(!)1008 4080 w
+(while\(true\){)1008 4190 w
+(lab=`{/usr/games/fortune $t})1 1512 1 1170 4300 t
+(echo $lab)1 486 1 1170 4410 t
+(if\(\304 $lab Holmdel\){)2 1026 1 1170 4520 t
+(echo You lose.)2 756 1 1332 4630 t
+(exit)1332 4740 w
+(})1170 4850 w
+(while\(read lab; ! grep -i -s $lab $t\) echo No such location.)11 3240 1 1170 4960 t
+(if\(\304 $lab [hH]olmdel\){)2 1188 1 1170 5070 t
+(echo You win.)2 702 1 1332 5180 t
+(exit)1332 5290 w
+(})1170 5400 w
+(})1008 5510 w
+10 B f
+(27. Discussion)1 626 1 720 5690 t
+10 R f
+(Steve Bourne's)1 622 1 720 5846 t
+10 CW f
+(/bin/sh)1376 5846 w
+10 R f
+( I)1 93( comparison.)1 526(is extremely well-designed; any successor is bound to suffer in)9 2591 3 1830 5846 t
+( things wherever possible, usually by)5 1512(have tried to fix its best-acknowledged shortcomings and to simplify)9 2808 2 720 5966 t
+( I)1 67( Obviously)1 475( when irresistibly tempted have I introduced novel ideas.)8 2330( Only)1 258(omitting unessential features.)2 1190 5 720 6086 t
+(have tinkered extensively with Bourne's syntax, that being where his work was most open to criticism.)15 4109 1 720 6206 t
+(The most important principle in)4 1284 1 720 6362 t
+10 I f
+(rc)2032 6362 w
+10 R f
+( is never scanned more)4 930( Input)1 265('s design is that it's not a macro processor.)8 1730 3 2115 6362 t
+( by the lexical and syntactic analysis code \(except, of course, by the)12 2885(than once)1 401 2 720 6482 t
+10 CW f
+(eval)4046 6482 w
+10 R f
+(command, whose)1 714 1 4326 6482 t
+10 I f
+(raison d'etre)1 519 1 720 6602 t
+10 R f
+(is to break the rule\).)4 801 1 1264 6602 t
+( These)1 298( arguments containing spaces.)3 1228(Bourne shell scripts can often be made to run wild by passing them)12 2794 3 720 6758 t
+(will be split into multiple arguments using)6 1780 1 720 6878 t
+10 CW f
+(IFS)2539 6878 w
+10 R f
+( In)1 146( inopportune times.)2 801(, often as)2 391 3 2719 6878 t
+10 I f
+(rc)4095 6878 w
+10 R f
+(, values of variables,)3 862 1 4178 6878 t
+( have)1 227( Arguments)1 508( when substituted into a command.)5 1464(including command line arguments, are not re-read)6 2121 4 720 6998 t
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+saveobj restore
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+9 CW f
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+(Where Bourne's syntax draws from Algol 68,)6 1917 1 720 5862 t
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+( Even)1 266( something darker: nobody really knows what the Bourne shell's grammar is.)11 3206(sight, but it suggests)3 848 3 720 2842 t
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+( distinguish between parentheses that immediately follow a word with no intervening)11 3614(lexical kludge to)2 706 2 720 3598 t
+( use for)2 319(spaces and those that don't that I would eliminate if there were a reasonable pair of characters to)17 4001 2 720 3718 t
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+10 B f
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+10 R f
+( Plan 9 users have been insistent, incessant sources of good ideas and)12 2825(Rob Pike, Howard Trickey and other)5 1495 2 720 4234 t
+( examples in this document are plagiarized from [Bou78], as are most of)12 2892(criticism. Some)1 653 2 720 4354 t
+10 I f
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+10 R f
+('s good features.)2 662 1 4373 4354 t
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+(29. References)1 639 1 720 4594 t
+10 R f
+( R. Bourne, ``U)3 678(Bou78. S.)1 423 2 720 4822 t
+8 R f
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+10 R f
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+8 R f
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+10 B f
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+(\(6\), pp. 1971-1990 \(July-August 1978\).)4 1579 1 1070 4942 t
+( Reeds, ``)2 409(Ree88. J.)1 394 2 720 5098 t
+10 CW f
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+( Bell)1 205( AT&T)1 334(: the biggest UNIX security loophole,'' 11217-840302-04TM,)6 2558 3 1943 5098 t
+(Laboratories \(1988\).)1 820 1 970 5218 t
+cleartomark
+showpage
+saveobj restore
+%%EndPage: 14 14
+%%Trailer
+done
+%%Pages: 14
+%%DocumentFonts: Courier Times-Bold Times-Italic Times-Roman Symbol
projects / unix-history / commitdiff