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XSTR(1) 		     General Commands Manual			 XSTR(1)

NAME
     xstr -- extract strings from C programs to implement shared strings

SYNOPSIS
     xstr [-cv] [-] [file ...]

DESCRIPTION
     The  xstr	utility maintains a file strings into which strings in component
     parts of a large program are hashed.  These strings are replaced with  ref-
     erences  to  this	common	area.	This serves to implement shared constant
     strings, most useful if they are also read-only.

     The following options are available:

     -	     Read from the standard input.

     -c      Extract the strings from the C source file or  the  standard  input
	     (-),  replacing  string  references  by  expressions  of  the  form
	     (&xstr[number]) for some number.	An  appropriate  declaration  of
	     xstr  is  prepended to the file.  The resulting C text is placed in
	     the file x.c, to then be compiled.  The strings from this file  are
	     placed in the strings data base if they are not there already.  Re-
	     peated  strings  and strings which are suffixes of existing strings
	     do not cause changes to the data base.

     -v      Verbose mode.

     After all components of a large program have been compiled a file xs.c  de-
     claring the common xstr space can be created by a command of the form

	   xstr

     The  file xs.c should then be compiled and loaded with the rest of the pro-
     gram.  If possible, the array can be made read-only (shared)  saving  space
     and swap overhead.

     The xstr utility can also be used on a single file.  A command

	   xstr name

     creates  files  x.c  and  xs.c  as  before,  without using or affecting any
     strings file in the same directory.

     It may be useful to run xstr after the C preprocessor if any macro  defini-
     tions  yield strings or if there is conditional code which contains strings
     which may not, in fact, be needed.  An  appropriate  command  sequence  for
     running xstr after the C preprocessor is:

	   cc -E name.c | xstr -c -
	   cc -c x.c
	   mv x.o name.o

     The  xstr	utility  does  not  touch  the file strings unless new items are
     added, thus make(1) can avoid remaking xs.o unless truly necessary.

FILES
     strings   data base of strings
     x.c       massaged C source
     xs.c      C source for definition of array xstr
     /tmp/xs*  temporary file when "xstr name" does not touch strings

SEE ALSO
     mkstr(1)

HISTORY
     The xstr command appeared in 3.0BSD.

BUGS
     If a string is a suffix of another string in the data base, but the shorter
     string is seen first by xstr both strings will be placed in the data  base,
     when just placing the longer one there will do.

FreeBSD 15.1			December 30, 1993			 XSTR(1)
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