22.2. Keeping Build Output Consistent
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## 22.2. Keeping Build Output Consistent

One potential drawback to using a derived-file cache is that the output printed by SCons can be inconsistent from invocation to invocation, because any given file may be rebuilt one time and retrieved from the derived-file cache the next time. This can make analyzing build output more difficult, especially for automated scripts that expect consistent output each time.

If, however, you use the `--cache-show` option, SCons will print the command line that it would have executed to build the file, even when it is retrieving the file from the derived-file cache. This keeps the build output consistent across builds:

    % scons -Q
    cc -o hello.o -c hello.c
    cc -o hello hello.o
    % scons -Q -c
    Removed hello.o
    Removed hello
    % scons -Q --cache-show
    cc -o hello.o -c hello.c
    cc -o hello hello.o

The trade-off, of course, is that you no longer know whether or not SCons has retrieved a derived file from cache or has rebuilt it locally.

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