# 2.11BSD#431 - /usr/man/cat1/xstr.0

    XSTR(1)             UNIX Programmer's Manual		  XSTR(1)

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

    SYNOPSIS
         xstr [ -c ] [ - ] [ file ]

    DESCRIPTION
         Xstr maintains a file strings into which strings in com-
         ponent 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.

         The command

    	  xstr -c name

         will extract the strings from the C source in name, replac-
         ing 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.  Repeated strings and strings which
         are suffices of existing strings do not cause changes to the
         data base.

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

    	  xstr

         This xs.c file 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.

         Xstr 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 definitions yield strings or if there is conditional
         code which contains strings which may not, in fact, be
         needed.  Xstr reads from its standard input when the argu-
         ment `-' is given.  An appropriate command sequence for run-
         ning xstr after the C preprocessor is:

    Printed 11/26/99	   May 7, 1986				1

    XSTR(1)             UNIX Programmer's Manual		  XSTR(1)

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

         Xstr does not touch the file strings unless new items are
         added, thus make can avoid remaking xs.o unless truly neces-
         sary.

    FILES
         strings	    Data base of strings
         x.c       Massaged C source
         xs.c      C source for definition of array `xstr'
         /tmp/xs*  Temp file when `xstr name' doesn't touch strings

    SEE ALSO
         mkstr(1)

    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.

    Printed 11/26/99	   May 7, 1986				2

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