XSTR(1) General Commands Manual XSTR(1)
xstr - extract strings from C programs to implement shared strings
xstr -c filename [ -v ] [ -l array ]
xstr [ -l array ]
xstr filename [ -v ] [ -l array ]
xstr maintains a file called 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 con-
stant strings, which are most useful if they are also read-only.
xstr -c filename
extracts the strings from the C source in name, replacing string refer-
ences by expressions of the form &&xstr[number] for some number. An
appropriate declaration of xstr is prepended to the file. The result-
ing 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 suffixes of
existing strings do not cause changes to the data base.
After all components of a large program have been compiled, a file
declaring the common xstr space called xs.c 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) 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 same directory.
It may be useful to run xstr after the C preprocessor if any macro def-
initions yield strings or if there is conditional code which contains
strings which may not, in fact, be needed. xstr reads from the stan-
dard input when the argument `-' is given. An appropriate 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(1) can avoid remaking xs.o unless truly necessary.
-c filename Take C source text from filename.
-v Verbose: display a progress report indicating where new or
duplicate strings were found.
-l array Specify the named array in program references to abstracted
strings. The default array name is xstr.
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 filename 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 would do.
19 April 1989 XSTR(1)