redirection from/to stdin or stdout [dash].

(cd /source/directory && tar cf - . ) | (cd /dest/directory && tar xpvf -)
# Move entire file tree from one directory to another
# [courtesy Alan Cox <a.cox@swansea.ac.uk>, with a minor change]

# 1) cd /source/directory    Source directory, where the files to be moved are.
# 2) &&                     "And-list": if the 'cd' operation successful, then execute the next command.
# 3) tar cf - .              The 'c' option 'tar' archiving command creates a new archive,
#                            the 'f' (file) option, followed by '-' designates the target file as stdout,
#                            and do it in current directory tree ('.').
# 4) |                       Piped to...
# 5) ( ... )                 a subshell
# 6) cd /dest/directory      Change to the destination directory.
# 7) &&                     "And-list", as above
# 8) tar xpvf -              Unarchive ('x'), preserve ownership and file permissions ('p'),
#                            and send verbose messages to stdout ('v'),
#                            reading data from stdin ('f' followed by '-').
#
#                            Note that 'x' is a command, and 'p', 'v', 'f' are options.
# Whew!



# More elegant than, but equivalent to:
#   cd source/directory
#   tar cf - . | (cd ../dest/directory; tar xpvf -)
#
# cp -a /source/directory /dest/directory     also has same effect.