XSTR(1)								       XSTR(1)

NAME    [Toc]    [Back]

     xstr - extract strings from C programs to implement shared	strings

SYNOPSIS    [Toc]    [Back]

     xstr [ -v ] [ [ -c	] [ - ]	[ file ]

DESCRIPTION    [Toc]    [Back]

     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 -v	flag makes xstr	verbose.

     The command

	  xstr -c name

     will extract the strings from the C source	in name, 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.	 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 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
	  mv x.o name.o






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XSTR(1)								       XSTR(1)



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

FILES    [Toc]    [Back]

     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    [Toc]    [Back]

     mkstr(1)

AUTHOR    [Toc]    [Back]

     William Joy

BUGS    [Toc]    [Back]

     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.


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