On Sat, 26 Jun 2004, Cameron Simpson wrote:
On 17:34 25 Jun 2004, Robert P. J. Day <rpjday@xxxxxxxxxxxxxx> wrote: | say i have a directory structure a/b/c/{f1,f2,f3,...}. for access | reasons, i decide to change the permissions on the "c" directory, | perhaps changing the owner/group, and definitely changing the perms to | include "setgid". | later, i get a tarball with contents a/b/c/{something}. i found out | that if i extract that tarball while root, and the effect is to add or | delete files under the "c" directory, the permissions on "c" revert | back to default values. how annoying.
I think you'll find the tarball also has "a/b/c" in it too.
sure, but the attributes of *those* directories don't get changed when i do the extraction.
| apparently, as long as what i'm extracting is already in that | directory (so that the directory entries themselves don't change), i'm | safe. but if the extraction changes the directory contents | themselves, i get the owner/group/perms resetting on "c", which i'd | *really* like to avoid. | | i've perused the tar options, and i don't see anything that says, | "don't mess with existing options on existing directories." is there | a standard approach to handle this?
1: Don't extract as root?
not an option. a single package/tarball might want to put files/dirs in various places, owned by various accounts.
2: Note perms, extract, fix perms.
ouch. that would work, but it would definitely be a bit messy.
3: Extract only the files - avoid the directories.
tempting, but i'm wondering what would happen if the tarball has a directory that doesn't exist yet. it will have to be created, of course, at which point i'd have to take care of setting its original
attributes.
A tar file has entries for the dirs, which is of course where the perms are. Don't as for them:
tar xvf tarfile a/b/c/f1 a/b/c/f2 ...
You could do this algorithmicly by doing a table of contents, sucking out the filenames, then doing the extract.
again, i can't just assume that all of the directories in the tarball already exist on the system. dang. i was really after the hypothetical tar option "do *not* screw with the attributes of existing objects." i don't think i'm going to find it.
rday
