xref: /freebsd/usr.bin/xstr/xstr.1 (revision 282a3889ebf826db9839be296ff1dd903f6d6d6e)
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32.\"     @(#)xstr.1	8.2 (Berkeley) 12/30/93
33.\" $FreeBSD$
34.\"
35.Dd December 30, 1993
36.Dt XSTR 1
37.Os
38.Sh NAME
39.Nm xstr
40.Nd "extract strings from C programs to implement shared strings"
41.Sh SYNOPSIS
42.Nm
43.Op Fl cv
44.Op Fl
45.Op Ar
46.Sh DESCRIPTION
47The
48.Nm
49utility maintains a file
50.Pa strings
51into which strings in component parts of a large program are hashed.
52These strings are replaced with references to this common area.
53This serves to implement shared constant strings, most useful if they
54are also read-only.
55.Pp
56The following options are available:
57.Bl -tag -width indent
58.It Fl
59Read from the standard input.
60.It Fl c
61Extract the strings from the C source
62.Ar file
63or the standard input
64.Pq Fl ,
65replacing
66string references by expressions of the form (&xstr[number])
67for some number.
68An appropriate declaration of
69.Nm
70is prepended to the file.
71The resulting C text is placed in the file
72.Pa x.c ,
73to then be compiled.
74The strings from this file are placed in the
75.Pa strings
76data base if they are not there already.
77Repeated strings and strings which are suffixes of existing strings
78do not cause changes to the data base.
79.It Fl v
80Verbose mode.
81.El
82.Pp
83After all components of a large program have been compiled a file
84.Pa xs.c
85declaring the common
86.Nm
87space can be created by a command of the form
88.Bd -literal -offset indent
89xstr
90.Ed
91.Pp
92The file
93.Pa xs.c
94should then be compiled and loaded with the rest
95of the program.
96If possible, the array can be made read-only (shared) saving
97space and swap overhead.
98.Pp
99The
100.Nm
101utility can also be used on a single file.
102A command
103.Bd -literal -offset indent
104xstr name
105.Ed
106.Pp
107creates files
108.Pa x.c
109and
110.Pa xs.c
111as before, without using or affecting any
112.Pa strings
113file in the same directory.
114.Pp
115It may be useful to run
116.Nm
117after the C preprocessor if any macro definitions yield strings
118or if there is conditional code which contains strings
119which may not, in fact, be needed.
120An appropriate command sequence for running
121.Nm
122after the C preprocessor is:
123.Pp
124.Bd -literal -offset indent -compact
125cc \-E name.c | xstr \-c \-
126cc \-c x.c
127mv x.o name.o
128.Ed
129.Pp
130The
131.Nm
132utility does not touch the file
133.Pa strings
134unless new items are added, thus
135.Xr make 1
136can avoid remaking
137.Pa xs.o
138unless truly necessary.
139.Sh FILES
140.Bl -tag -width /tmp/xsxx* -compact
141.It Pa strings
142data base of strings
143.It Pa x.c
144massaged C source
145.It Pa xs.c
146C source for definition of array `xstr'
147.It Pa /tmp/xs*
148temp file when `xstr name' does not touch
149.Pa strings
150.El
151.Sh SEE ALSO
152.Xr mkstr 1
153.Sh HISTORY
154The
155.Nm
156command appeared in
157.Bx 3.0 .
158.Sh BUGS
159If a string is a suffix of another string in the data base,
160but the shorter string is seen first by
161.Nm
162both strings will be placed in the data base, when just
163placing the longer one there will do.
164