GNU: http://www.gnu.org/software/cpio/manual/cpio.html. Ubuntu cpio package.
Was POSIX.1-1988, but it was omitted from POSIX.1-2001. The POSIX 2008 pax utility defines and implements the cpio format however. The file format is very simple.
Copy files between archives. Also the name of a specialized archive format of the program.
Generate a .cpio archive containing files a and b:
printf '0' > /tmp/a
printf '1' > /tmp/b
printf '/tmp/a\n/tmp/b\n' | cpio -o > /tmp/ab.cpio
hd /tmp/ab.cpio
Find selected files and add them to the archive, building and keeping their relative directory structure:
find . -type f | cpio -pvdumB /tmp/find.cpio
Decompress cpio archive:
cpio -i <ab.cpio