XSTR(1,C)                   AIX Commands Reference                    XSTR(1,C)



-------------------------------------------------------------------------------
xstr



PURPOSE

Maintains a file "strings".

SYNTAX


        +--------+   +--------+
xstr ---| +----+ |---|        |---|
        +-| -c |-+   +- file -+
         ^| -  ||
         |+----+|
         +------+


Note:  This command does not have MBCS support.

DESCRIPTION

The xstr command 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 name extracts 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.

The xstr command 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:



Processed November 8, 1990         XSTR(1,C)                                  1

XSTR(1,C)                   AIX Commands Reference                    XSTR(1,C)




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

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

Note:  If a string is a suffix of another string in the data base but the
       shorter string is seen first by the xstr command, both strings are
       placed in the data base, when just placing the longer one there is
       sufficient.

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.

RELATED INFORMATION

See the following command:  "mkstr."
































Processed November 8, 1990         XSTR(1,C)                                  2