Pádraig Brady wrote: > Subject: [PATCH] truncate: support sizes relative to an existing file > > * doc/coreutils.texi (truncate invocation): Mention that --reference > bases the --size rather than just setting it. > * src/truncate.c (usage): Likewise. Also remove the clause > describing --size and --reference as being mutually exclusive. > (do_truncate): Add an extra parameter to hold the size > of a referenced file, and use it if positive. > (main): Pass the size of a referenced file to do_truncate(). > * tests/misc/truncate-parameters: Adjust for the new combinations. > * NEWS: Mention the change > Suggested by Richard W.M. Jones
Nice. Thanks! Not new with this change, but what about --ref=non-regular-file ? Perhaps truncate should refuse to use st_size info from a non-regular file. Here's a pathological example: $ echo abcdefgh > bar $ strace -e ftruncate ./truncate --ref=/dev/tty bar ftruncate(3, 0) = 0 $ wc -c bar 0 bar It's obvious that such an example is not likely in practice, but since currently truncate's --ref uses stat, it would follow a symlink, too. For a directory you'd get unportable and probably surprising results. Using such a reference size deserves at least a warning.
