XSTR(1)                 COMMAND REFERENCE                 XSTR(1)



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

SYNOPSIS
     xstr [ -c ] [ - ] [ filename ]

DESCRIPTION
     Xstr maintains a file 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.  The command

               xstr -c filename

     will extract the strings from the C source in filename,
     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 database if they
     are not there already.  Repeated strings and strings which
     are suffices of existing strings do not cause changes to the
     database.

     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 filename

     creates the 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 dash
     argument (-) is given.  An appropriate command sequence for
     running xstr after the C preprocessor is:

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



Printed 10/17/86                                                1

XSTR(1)                 COMMAND REFERENCE                 XSTR(1)



          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
     necessary.

OPTIONS
     -c  Xstr extracts strings from the C source in the given
         file.

     -   Xstr reads from the standard input.

FILES
     strings                  Database of strings.

     x.c                      Massaged C source.

     xs.c                     C source for definition of array
                              xstr.

     /tmp/xs*                 Temporary file when xstr filename
                              doesn't touch strings.

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

SEE ALSO
     cc(1), mv(1).
























Printed 10/17/86                                                2

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de:331,2328;2803,233;
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fi:3276,470;
ca:3746,293;
se:4039,103;
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