BSD 2.11 - man page for xstr (bsd section 1)
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xstr - extract strings from C programs to implement shared strings
xstr [ -c ] [ - ] [ file ]
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.
xstr -c name
will extract the strings from the C source in name, replacing string references by expres-
sions 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 com-
piled. 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 com-
mon xstr 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 possi-
ble, the array can be made read-only (shared) saving space and swap overhead.
Xstr can also be used on a single file. A command
creates files x.c and xs.c as before, without using or affecting any strings file in the
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 appropri-
ate 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
Xstr does not touch the file strings unless new items are added, thus make can avoid
remaking xs.o unless truly necessary.
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
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.
3rd Berkeley Distribution May 7, 1986 XSTR(1)
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