xref: /titanic_52/usr/src/cmd/oawk/README (revision cc7a88b54b4969574f03e1a1225bb13be487f5db)
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22#ident	"%Z%%M%	%I%	%E% SMI"
23CHANGES as of July 12:
24
251. \ddd allowed in regular expressions.
26
272. exit <expression> causes the expression to
28to be the status return upon completion.
29
303. a new builtin called "getline" causes the next
31input line to be read immediately.  Fields, NR, etc.,
32are all set, but you are left at exactly the same place
33in the awk program.  Getline returns 0 for end of file;
341 for a normal record.
35
36
37CHANGES SINCE MEMO:
38Update to TM of Sept 1, 1978:
39
401. A new form of for loop
41	for (i in array)
42		statement
43is now available. It provides a way to walk
44along the members of an array, most usefully
45for associative arrays with non-numeric subscripts.
46Elements are accessed in an unpredictable order,
47so don't count on anything.
48Futhermore, havoc ensues if elements are created
49during this operation, or if the index variable
50is fiddled.
51
522. index(s1, s2) returns the position in s1
53where s2 first occurs, or 0 if it doesn't.
54
553. Multi-line records are now supported more
56conveniently. If the record separator is null
57	RS = ""
58then a blank line terminates a record, and newline
59is a default field separator, along with
60blank and tab.
61
624. The syntax of split has been changed.
63	n = split(str, arrayname, sep)
64splits the string str into the array using
65the separator sep (a single character).
66If no sep field is given, FS is used instead.
67The elements are array[1] ... array[n]; n
68is the function value.
69
705. some minor bugs have been fixed.
71
72IMPLEMENTATION NOTES:
73
74Things to watch out for when trying to make awk:
75
761. The yacc -d business creates a new file y.tab.h
77with the yacc #defines in it. this is compared to
78awk.h on each successive compile, and major recompilation
79is done only if the files differ. (This permits editing
80the grammar file without causing everything in sight
81to be recompiled, so long as the definitions don't
82change.)
83
842. The program proc.c is compiled into proc, which
85is used to create proctab.c. proctab.c is the
86table of function pointers used by run to actually
87execute things. Don't try to load proc.c with the
88other .c files; it also contains a "main()".
89
903. Awk uses structure assignment. Be sure your
91version of the C compiler has it.
92
934. The loader flag -lm is used to fetch the standard
94math library on the Research system. It is more likely
95that you will want to use -lS on yours.
96run.c also includes "math.h", which contains sensible
97definitions for log(), sqrt(), etc. If you don't have this
98include file, comment the line out, and all will be well
99anyway.
100
1015. The basic sequence of events (in case make doesn't
102seem to do the job) is
103	yacc -d awk.g.y
104	cc -O -c y.tab.c
105	mv y.tab.o awk.g.o
106	lex awk.lx.l
107	cc -O -c lex.yy.c
108	mv lex.yy.o awk.lx.o
109	cc -O -c b.c
110	cc -O -c main.c
111	e - <tokenscript
112	cc -O -c token.c
113	cc -O -c tran.c
114	cc -O -c lib.c
115	cc -O -c run.c
116	cc -O -c parse.c
117	cc -O -c proc.c
118	cc -o proc proc.c token.o
119	proc >proctab.c
120	cc -O -c proctab.c
121	cc -i -O awk.g.o awk.lx.o b.o main.o token.o tran.o lib.o run.o parse.o proctab.o -lm
122