xstr(1) 						      General Commands Manual							   xstr(1)

NAME

       xstr - Extracts strings from C programs to implement shared strings

SYNOPSIS

       xstr [-c] [file | -]

       The xstr command maintains a file called strings into which strings in component parts of a large program are hashed.

OPTIONS

       Extracts strings from the specified file.

DESCRIPTION

       The  strings extracted by xstr are replaced with references to this array. This serves to implement shared constant strings, most useful if
       they are also read-only.

       The following command extracts the strings from the C source in file, replacing string references by expressions of  the  form  (&xstr[num-
       ber]) for some number.  xstr -c file

       The  xstr  command  uses  file as input; the resulting C text is placed in the file x.c to then be compiled. The strings from this file are
       appended to the strings file if they are not there already. Repeated strings and strings that are suffixes of existing strings do not cause
       changes to the file.

       If  a  string  is a suffix of another string in the file, but the shorter string is seen first by xstr, both strings are placed in the file
       strings.

       After all components of a large program are compiled, a file xs.c declaring the common xstr space can be created by a command of  the  fol-
       lowing form: xstr

       Compile and load this xs.c file with the rest of the program.  Some C compilers may, by default, put strings in a read-only text section.

       The xstr command can also be used on a single file.  The following command creates files x.c and xs.c as before, without using or affecting
       a strings file in the same directory.  xstr file

       It may be useful to run xstr after the C preprocessor if any macro definitions yield strings or if there is conditional code that  contains
       strings that may not be needed.	The xstr command reads from its standard input when the argument - (dash) is given. An appropriate command
       sequence for running xstr after the C preprocessor is as follows: cc -E file.c | xstr -c - cc -c x.c mv x.o file.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.

EXAMPLES

       To extract the strings from the C source in the file.c parameter, replacing string references by expressions of the  form  (&xstr[number]),
       enter: xstr -c file

	      An  appropriate declaration of the xstr array is prepended to file.  The resulting C text is placed in the file x.c, to then be com-
	      piled.  To declare the common xstr array space in the xs.c file, enter: xstr

FILES

       File that contains the extracted strings.  Modified C source.  C source for definition of array xstr.  Temporary file when the xstr command
       does not touch strings.

SEE ALSO

       Commands:  mkstr(1)

																	   xstr(1)