1XSTR(1)                     General Commands Manual                    XSTR(1)
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NAME

6       xstr - extract strings from C programs to implement shared strings
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SYNOPSIS

9       xstr [ -c ] [ - ] [ file ]
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DESCRIPTION

12       Xstr  maintains a file strings into which strings in component parts of
13       a large program are hashed.  These strings are replaced with references
14       to this common area.  This serves to implement shared constant strings,
15       most useful if they are also read-only.
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17       The command
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19            xstr -c name
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21       will extract the strings from the C source in  name,  replacing  string
22       references  by expressions of the form (&xstr[number]) for some number.
23       An appropriate declaration of xstr  is  prepended  to  the  file.   The
24       resulting  C  text is placed in the file x.c, to then be compiled.  The
25       strings from this file are placed in the strings data base if they  are
26       not  there already.  Repeated strings and strings which are suffices of
27       existing strings do not cause changes to the data base.
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29       After all components of a large program have been compiled a file  xs.c
30       declaring the common xstr space can be created by a command of the form
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32            xstr
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34       This  xs.c file should then be compiled and loaded with the rest of the
35       program.  If possible, the array can be made read-only (shared)  saving
36       space and swap overhead.
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38       Xstr can also be used on a single file.  A command
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40            xstr name
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42       creates  files  x.c  and xs.c as before, without using or affecting any
43       strings file in the same directory.
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45       It may be useful to run xstr after the C preprocessor if any macro def‐
46       initions  yield  strings or if there is conditional code which contains
47       strings which may not, in fact, be needed.  Xstr reads from  its  stan‐
48       dard  input  when  the  argument  `-' is given.  An appropriate command
49       sequence for running xstr after the C preprocessor is:
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51            cc -E name.c | xstr -c -
52            cc -c x.c
53            mv x.o name.o
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55       Xstr does not touch the file strings unless new items are  added,  thus
56       make can avoid remaking xs.o unless truly necessary.
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FILES

59       strings        Data base of strings
60       x.c       Massaged C source
61       xs.c      C source for definition of array `xstr'
62       /tmp/xs*  Temp file when `xstr name' doesn't touch strings
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SEE ALSO

65       mkstr(1)
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BUGS

68       If  a  string  is  a suffix of another string in the data base, but the
69       shorter string is seen first by xstr both strings will be placed in the
70       data base, when just placing the longer one there will do.
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743rd Berkeley Distribution         May 7, 1986                          XSTR(1)