Path: utzoo!mnetor!uunet!husc6!think!ames!pasteur!ucbvax!decwrl!labrea!denali!karish From: karish@denali.stanford.edu (karish) Newsgroups: comp.unix.questions Subject: Re: cpio Message-ID: <72@denali.domain> Date: 7 May 88 15:04:44 GMT References: <625@mccc.UUCP> Reply-To: karish@denali.stanford.edu (Chuck Karish) Distribution: na Organization: Mindcraft, Inc. Lines: 29 Keywords: diskette, tape Summary: cpio will write a second file on the medium In article <625@mccc.UUCP> pjh@mccc.UUCP (Peter J. Holsberg) writes: > >Do cpio and ctccpio always overwrite anything that is already on the >diskette or tape? If so, is there any 'copy' program that does not? >Thanks. cpio only overwrites what's on a tape if you tell it to. If you use a no-rewind tape special device, and space to the end of the previous file first, you can write a second file onto the tape after the first one. On BSD systems, the `mt' utility lets you reposition the tape. The comparable AIX command is `tctl'. I don't know whether this is a standard SysV command. Of course, you have to remember that there are two files on the tape when you extract data. It's harder to do this on diskettes. Piping cpio to dd might do the trick, if you specify one of the `skip' options to dd. The tar command will append to an archive, if you use the 'r' flag. This is usable for incremental backups. The disadvantage is that it's impossible to extract earlier versions of files from the archive; the tape is read in order, and later versions overwrite earlier ones on extraction. Chuck Karish ARPA: karish@denali.stanford.edu BITNET: karish%denali@forsythe.stanford.edu UUCP: {decvax,hplabs!hpda}!mindcrf!karish paper: 1825 California St. #5 Mountain View, CA 94041