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.\"     @(#)xstr.1	8.2 (Berkeley) 12/30/93
.\" $FreeBSD$
.\"
.Dd December 30, 1993
.Dt XSTR 1
.Os
.Sh NAME
.Nm xstr
.Nd "extract strings from C programs to implement shared strings"
.Sh SYNOPSIS
.Nm
.Op Fl cv
.Op Fl
.Op Ar
.Sh DESCRIPTION
The
.Nm
utility maintains a file
.Pa strings
into which strings in component parts of a large program are hashed.
These strings are replaced with references to this common area.
This serves to implement shared constant strings, most useful if they
are also read-only.
.Pp
The following options are available:
.Bl -tag -width indent
.It Fl
Read from the standard input.
.It Fl c
Extract the strings from the C source
.Ar file
or the standard input
.Pq Fl ,
replacing
string references by expressions of the form
.Li (&xstr[number])
for some
.Ar number .
An appropriate declaration of
.Va xstr
is prepended to the file.
The resulting C text is placed in the file
.Pa x.c ,
to then be compiled.
The strings from this file are placed in the
.Pa strings
data base if they are not there already.
Repeated strings and strings which are suffixes of existing strings
do not cause changes to the data base.
.It Fl v
Verbose mode.
.El
.Pp
After all components of a large program have been compiled a file
.Pa xs.c
declaring the common
.Va xstr
space can be created by a command of the form
.Pp
.Dl xstr
.Pp
The file
.Pa xs.c
should then be compiled and loaded with the rest
of the program.
If possible, the array can be made read-only (shared) saving
space and swap overhead.
.Pp
The
.Nm
utility can also be used on a single file.
A command
.Bd -literal -offset indent
xstr name
.Ed
.Pp
creates files
.Pa x.c
and
.Pa xs.c
as before, without using or affecting any
.Pa strings
file in the same directory.
.Pp
It may be useful to run
.Nm
after the C preprocessor if any macro definitions yield strings
or if there is conditional code which contains strings
which may not, in fact, be needed.
An appropriate command sequence for running
.Nm
after the C preprocessor is:
.Pp
.Bd -literal -offset indent -compact
cc -E name.c | xstr -c -
cc -c x.c
mv x.o name.o
.Ed
.Pp
The
.Nm
utility does not touch the file
.Pa strings
unless new items are added, thus
.Xr make 1
can avoid remaking
.Pa xs.o
unless truly necessary.
.Sh FILES
.Bl -tag -width ".Pa /tmp/xs*" -compact
.It Pa strings
data base of strings
.It Pa x.c
massaged C source
.It Pa xs.c
C source for definition of array
.Va xstr
.It Pa /tmp/xs*
temporary file when
.Dq Li "xstr name"
does not touch
.Pa strings
.El
.Sh SEE ALSO
.Xr mkstr 1
.Sh HISTORY
The
.Nm
command appeared in
.Bx 3.0 .
.Sh BUGS
If a string is a suffix of another string in the data base,
but the shorter string is seen first by
.Nm
both strings will be placed in the data base, when just
placing the longer one there will do.