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28 .\" @(#)xstr.1 8.2 (Berkeley) 12/30/93
35 .Nd "extract strings from C programs to implement shared strings"
44 utility maintains a file
46 into which strings in component parts of a large program are hashed.
47 These strings are replaced with references to this common area.
48 This serves to implement shared constant strings, most useful if they
51 The following options are available:
52 .Bl -tag -width indent
54 Read from the standard input.
56 Extract the strings from the C source
61 string references by expressions of the form
65 An appropriate declaration of
67 is prepended to the file.
68 The resulting C text is placed in the file
71 The strings from this file are placed in the
73 data base if they are not there already.
74 Repeated strings and strings which are suffixes of existing strings
75 do not cause changes to the data base.
80 After all components of a large program have been compiled a file
84 space can be created by a command of the form
90 should then be compiled and loaded with the rest
92 If possible, the array can be made read-only (shared) saving
93 space and swap overhead.
97 utility can also be used on a single file.
99 .Bd -literal -offset indent
107 as before, without using or affecting any
109 file in the same directory.
111 It may be useful to run
113 after the C preprocessor if any macro definitions yield strings
114 or if there is conditional code which contains strings
115 which may not, in fact, be needed.
116 An appropriate command sequence for running
118 after the C preprocessor is:
120 .Bd -literal -offset indent -compact
121 cc -E name.c | xstr -c -
128 utility does not touch the file
130 unless new items are added, thus
134 unless truly necessary.
136 .Bl -tag -width ".Pa /tmp/xs*" -compact
142 C source for definition of array
158 If a string is a suffix of another string in the data base,
159 but the shorter string is seen first by
161 both strings will be placed in the data base, when just
162 placing the longer one there will do.