The current version of `sponge(1)` from moreutils always write to TMPDIR for atomic write, even if we point it to stdout.
This will double the wearout of flash storage if target is stdout, e.g:
$ wget .... | sponge | sort | rev > filename.txt
the data will got written to flash storage in twice:
`$TMPDIR/spongeXXXX` and sort/rev'd `filename.txt`.
Since on unrooted device `TMPDIR` is usually not a tmpfs, using sponge in similar cases will result in unnecessary wearout of flash storage when:
- invoke sponge w/o params, or target is stdout
- end of pipeline point to a file in a filesystem different than TMPDIR resides
In case of the length of input data is prior known or splited to less than available memory, we can use `rw` instead.
flos