xstr(1) 						      General Commands Manual							   xstr(1)

       xstr - extract strings from C program

       xstr [-c] [-] [file]

       The  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

       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 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 space can be created by a command of the form

       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) sav-
       ing space and swap overhead.

       The 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 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.  The command reads from its standard input when the argument `-' is given.  An appropriate com-
       mand sequence for running after the C preprocessor is:
       cc -E name.c | xstr -c -
       cc -c x.c
       mv x.o name.o

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

       -  Reads stdin.

       -c Extracts strings from specified C source (next argument).

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

       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


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