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1.1 root 1: .TH DBZ 1 "11 Feb 1992"
2: .BY "C News"
3: .SH NAME
4: dbz \- operate on dbz databases of text
5: .SH SYNOPSIS
6: .B dbz
7: [
8: .BR \- { axmc }
9: ] [
10: .B \-t
11: c
12: ] [
13: .B \-l
14: length
15: ] [
16: .BR \- { qiue }
17: ] [
18: .B \-f
19: old
20: ] [
21: .B \-p
22: parms
23: ] database file ...
24: .SH DESCRIPTION
25: .I Dbz
26: is a shell-level interface to the
27: .IR dbz (3z)
28: database routines for indexed access to a text file.
29: .PP
30: The
31: .I database
32: file must be a text file,
33: one line per database record,
34: with the key the first field on the line.
35: The
36: .B \-t
37: option sets the field-separator character; the default is tab.
38: Setting the separator character to NUL (with
39: .BR "\-t\ ''" )
40: makes the whole line the key.
41: Lines must not exceed 1023 bytes in length including the newline;
42: this limit can be increased with the
43: .B \-l
44: option.
45: The limitations and restrictions of
46: .IR dbz (3z)
47: must also be observed;
48: in particular, it remains the user's responsibility to ensure that
49: no attempt is made to store two entries (whether identical or not)
50: with the same key.
51: .PP
52: In the absence of options,
53: .I dbz
54: creates a
55: .IR dbz (3z)
56: index for the database;
57: the index comprises files
58: .IB database .pag
59: and
60: .IB database .dir
61: in the same directory.
62: Any previous index is silently overwritten.
63: The
64: .BR \-a ,
65: .BR \-x ,
66: .BR \-m ,
67: and
68: .B \-c
69: options specify other operations.
70: .PP
71: With
72: .BR \-a ,
73: .I dbz
74: appends lines from the
75: .IR file (s)
76: (standard input if none)
77: to the database, updating both the
78: text file and the indexes.
79: .PP
80: With
81: .BR \-x ,
82: .I dbz
83: reads keys from the
84: .IR file (s)
85: (standard input if none)
86: and prints (on standard output) the corresponding lines, if any,
87: from the database.
88: The input is in the form of database lines, although only the keys are
89: significant.
90: The
91: .B \-q
92: option makes
93: .B \-x
94: print the input lines whose keys are found instead of the database
95: lines; this is somewhat faster.
96: .PP
97: With
98: .BR \-m ,
99: operation is the same as for
100: .B \-x
101: except that the keys which are \fInot\fR present in the database are printed.
102: .PP
103: With
104: .BR \-c ,
105: .I dbz
106: checks the database for internal consistency.
107: The
108: .B \-q
109: option causes this check to be done more quickly but less thoroughly
110: (each key is looked up in the index, but no check is made to be sure
111: that the index entry points to the right place).
112: .PP
113: The
114: .B \-i
115: option suppresses the use of
116: .IR dbz (3z)'s
117: .I incore
118: facility.
119: This makes accesses slower, but keeps the files current
120: during updating
121: and reduces
122: startup/shutdown overhead.
123: .PP
124: Normally,
125: .I dbz
126: checks whether a key is already in the database before adding it.
127: The
128: .B \-u
129: option suppresses this check, speeding things up at the expense of safety.
130: .PP
131: A new index is normally created with default size,
132: case mapping, and tagging.
133: The default size is right for 90-100,000 records.
134: The default case mapping is right for RFC822 message-ids.
135: See
136: .IR dbz (3z)
137: for what tagging is about.
138: (Note, these defaults can be changed when
139: .IR dbz (3z)
140: is installed.)
141: .PP
142: If the
143: .B \-f
144: option is given,
145: size, case mapping, and tagging
146: are instead initialized based on the
147: database
148: .IR old .
149: This is mostly useful when
150: creating a new generation of an existing database.
151: (See the description of
152: .I dbzagain
153: in
154: .IR dbz (3z)
155: for details.)
156: .PP
157: If the
158: .B \-p
159: option is given, the
160: .I parms
161: string specifies the size, case mapping, and tagging.
162: If
163: .I parms
164: is a single decimal number,
165: that is taken as the expected number of records
166: in the index, with case mapping and tagging defaulted.
167: Alternatively,
168: .I parms
169: can be three fields\(ema decimal number, a case-mapping code character, and a
170: hexadecimal tag mask\(emseparated by white space.
171: The decimal number is, again, the expected number of records;
172: 0 means ``use the default''.
173: See
174: .IR dbz (3z)
175: for possible choices of case-mapping code,
176: but in particular,
177: .B 0
178: means ``no case mapping''.
179: See
180: .IR dbz (3z)
181: for details on tag masks;
182: 0 means ``use the default''.
183: .PP
184: If the
185: .B \-e
186: option is given, the decimal number in
187: .B \-p
188: is taken to be the exact table size, not the expected number of records,
189: and invocation of
190: .I dbzsize
191: (see
192: .IR dbz (3z))
193: to predict a good size for that number of records is suppressed.
194: .PP
195: The
196: .B \&.pag
197: file is normally about 6 bytes per record (based on the estimate given to
198: .B \-p
199: or the previous history of the
200: .B \-f
201: database).
202: The
203: .B \&.dir
204: file is tiny.
205: .SH SEE ALSO
206: dbz(3z)
207: .SH HISTORY
208: Written at U of Toronto by Henry Spencer, for the C News project.
209: See
210: .IR dbz (3z)
211: for the history of the underlying database routines.
212: .SH BUGS
213: There are a number of undocumented options with obscure effects,
214: meant for debugging and regression testing of
215: .IR dbz (3z).
216: .PP
217: Permissions for the index files probably ought to be taken from those
218: of the base file.
219: .PP
220: The line-length limit is a blemish, alleviated only slightly by
221: .BR \-l .
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