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28 .\" @(#)xstr.1 8.2 (Berkeley) 12/30/93
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36 .Nd "extract strings from C programs to implement shared strings"
45 utility maintains a file
47 into which strings in component parts of a large program are hashed.
48 These strings are replaced with references to this common area.
49 This serves to implement shared constant strings, most useful if they
52 The following options are available:
53 .Bl -tag -width indent
55 Read from the standard input.
57 Extract the strings from the C source
62 string references by expressions of the form
66 An appropriate declaration of
68 is prepended to the file.
69 The resulting C text is placed in the file
72 The strings from this file are placed in the
74 data base if they are not there already.
75 Repeated strings and strings which are suffixes of existing strings
76 do not cause changes to the data base.
81 After all components of a large program have been compiled a file
85 space can be created by a command of the form
91 should then be compiled and loaded with the rest
93 If possible, the array can be made read-only (shared) saving
94 space and swap overhead.
98 utility can also be used on a single file.
100 .Bd -literal -offset indent
108 as before, without using or affecting any
110 file in the same directory.
112 It may be useful to run
114 after the C preprocessor if any macro definitions yield strings
115 or if there is conditional code which contains strings
116 which may not, in fact, be needed.
117 An appropriate command sequence for running
119 after the C preprocessor is:
121 .Bd -literal -offset indent -compact
122 cc -E name.c | xstr -c -
129 utility does not touch the file
131 unless new items are added, thus
135 unless truly necessary.
137 .Bl -tag -width ".Pa /tmp/xs*" -compact
143 C source for definition of array
159 If a string is a suffix of another string in the data base,
160 but the shorter string is seen first by
162 both strings will be placed in the data base, when just
163 placing the longer one there will do.