Like the TAR
command, CPIO is used to backup or archive files and directories.
The
difference is that tar by default backup file to a tape device and backup all
of a specified directory, whereas cpio by default archive only the files you
tell it to using command line arguments. That’s why it’s always (almost) used
with other command to do backup/archive.
To start
with, backup a directory under /home/acheng/www:
#cd
/home/acheng/www
#find -d . |
cpio -ovF ../wwwbak.cpio
When using
the find
utility with cpio,
it is always a good idea to include either the d or the depth switch. This switch prevented
permissions from interfering with a backup. When using this switch, either put -d right after the word find and before the directory to
search (in this case, “.“),
or put the word -depthafter the
directory to search, like so:
#find . -depth -print | cpio -ov >
backup.cpio
To view the
contents of a cpio archive without
extracting, use:
# cpio -it
< ../wwwbak.cpio
To extract,
use:
#mkdir ../restore;cd
../restore
#cpio -ivd
< ../wwwbak.cpio
Note the d
switch, it tell cpio to create any dir when necessary. otherwise it’ll compain
not being able to find the dir to restore to.
You can also
use -p switch to let cpio emulate what cp can do with a directory or file, that
is to copy them over to a different place.
The benefit
of using cpio instead of cp is that you can fine tune the files/dirs you want
to copy with utilities like FIND and you can reserve a file’s create
time/modified time, plus you can reserve/change a file’s ownership at wish.
Let’s say
you want to backup the www dir to /tmp:
#cd
/home/acheng/www
#find -d . |
cpio -pvd /tmp
Or change the
ownership of all copied files to user alan:
#find -d . |
cpio -pvd -R alan /tmp
To reserve
all original time of these files, use:
#find -d . |
cpio -pvdam -R alan /tmp
** use “man
cpio” for more information and options with cpio
