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32 .\" @(#)xstr.1 8.2 (Berkeley) 12/30/93
33 .\" $FreeBSD: src/usr.bin/xstr/xstr.1,v 1.4.2.4 2002/06/21 15:30:26 charnier Exp $
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41 .Nd "extract strings from C programs to implement shared strings"
51 utility maintains a file
53 into which strings in component parts of a large program are hashed.
54 These strings are replaced with references to this common area.
55 This serves to implement shared constant strings, most useful if they
61 Read from the standard input.
63 Extract the strings from the C source
68 string references by expressions of the form (&xstr[number])
70 An appropriate declaration of
72 is prepended to the file.
73 The resulting C text is placed in the file
76 The strings from this file are placed in the
78 data base if they are not there already.
79 Repeated strings and strings which are suffixes of existing strings
80 do not cause changes to the data base.
85 After all components of a large program have been compiled a file
89 space can be created by a command of the form
90 .Bd -literal -offset indent
96 should then be compiled and loaded with the rest
98 If possible, the array can be made read-only (shared) saving
99 space and swap overhead.
103 utility can also be used on a single file.
105 .Bd -literal -offset indent
113 as before, without using or affecting any
115 file in the same directory.
117 It may be useful to run
119 after the C preprocessor if any macro definitions yield strings
120 or if there is conditional code which contains strings
121 which may not, in fact, be needed.
122 An appropriate command sequence for running
124 after the C preprocessor is:
126 .Bd -literal -offset indent -compact
127 cc \-E name.c | xstr \-c \-
134 utility does not touch the file
136 unless new items are added, thus
140 unless truly necessary.
142 .Bl -tag -width /tmp/xsxx* -compact
148 C source for definition of array `xstr'
150 Temp file when `xstr name' doesn't touch
161 If a string is a suffix of another string in the data base,
162 but the shorter string is seen first by
164 both strings will be placed in the data base, when just
165 placing the longer one there will do.