news@bjm.wimsey.bc.ca (News Login) (12/12/90)
Hi NET, I have this backup which I accidentally wrote a cpio archive over. However the cpio archive is only 20 megabytes and therefore 1/3 of the tape. What I really want to do is get past the cpio archive and just retreive the rest of the tape into a file and I will fix the remaining tar file by hand. My question is (drum roll please) how do get past the EOF marker at the end of the cpio? I've tried dd, cat, evmt (a utility which comes with ESIX [which I'm now running] which is similar to sco xenix's 'tape' utility) which allows me to get to the next eof but not past it. I don't really care how much past the eof I go (.5 to even 1 meg if I have to). I think what I mostly overwrote was the /bin /usr/bin stuff. Any ideas would be much appreciated.
kittlitz@mips2.cr.bull.com (Ned Kittlitz) (12/12/90)
In article <1990Dec12.050414.15575@bjm.wimsey.bc.ca> news@bjm.wimsey.bc.ca (News Login) writes: >Hi NET, > > I have this backup which I accidentally wrote a cpio archive over. >However, the cpio archive is only 20 megabytes and therefore 1/3 of the tape. You don't say so explicitly, but by the process of multiplication, I am going to assume that you are talking about a 60MB 1/4 inch cartridge tape. If so, several ravens which I have at hand quoth "nevermore". From the Archive Viper description of write: "QIC data can only be written over erased tape; therefor, when the Viper drive writes to track zero, the erase head is turned on to condition the entire tape". From the Wangtek OEM manual for 5099ES/5125ES/5150ES streaming 1/4 inch tape cartridge drive: "Tape is erased automatically while writing track zero." ---------- E. N. Kittlitz - consulting at Bull, and nothing more. kittlitz@world.std.com or kittlitz@granite.cr.bull.com
dag@fciva.FRANKLIN.COM (Daniel A. Graifer) (12/14/90)
In article <1990Dec12.050414.15575@bjm.wimsey.bc.ca> news@bjm.wimsey.bc.ca (News Login) writes: > I have this backup which I accidentally wrote a cpio archive over. >However, the cpio archive is only 20 megabytes and therefore 1/3 of the tape. I think what you are asking here is 'How do I read beyond the end of the EOF mark on the tape'. The problem is that, when whichever process you use to read past the first file closes the device, it automatically rewinds. There should be a different device (same major, different minor number) that is explicitly no-rewind-on-close. On my PRIME EXL (386 MultiBusII/SCSI, ATT Unix Sys V 3.1.2), I have: $ l /dev/rct total 0 crw-rw-rw- 2 root sys 1,160 Dec 13 12:19 c0d5 crw-rw-rw- 1 root sys 1,164 Jun 27 10:56 c0d5n crw-rw-rw- 1 root sys 1,165 Feb 18 1989 c0d5w $ Controller 0 (SCSI) device 5 (cartridge tape) no-rewind is the second device here. Once you've that device, use cpio or dd to read to the end of it, then reopen the either the regular or the no-rewind device with dd to suck in the data beyond the EOF mark. Don't forget to rewind the tape after the last read, before you pull it from the drive! Good luck Dan
randyj@bcs800.UUCP (Randy Jarrett) (12/15/90)
In <1990Dec12.050414.15575@bjm.wimsey.bc.ca> news@bjm.wimsey.bc.ca (News Login) writes: >Hi NET, > > I have this backup which I accidentally wrote a cpio archive over. However >the cpio archive is only 20 megabytes and therefore 1/3 of the tape. What I >really want to do is get past the cpio archive and just retreive the rest of >the tape into a file and I will fix the remaining tar file by hand. My >question is (drum roll please) >how do get past the EOF marker at the end of the cpio? I've tried dd, cat, >evmt (a utility which comes with ESIX [which I'm now running] which is similar >to sco xenix's 'tape' utility) which allows me to get to the next eof but >not past >it. I don't really care how much past the eof I go (.5 to even 1 meg if I have >to). I think what I mostly overwrote was the /bin /usr/bin stuff. I have had a similar experence in the recent past. What I was able to do was to read the first portion (your cpio) with the -ivtc option and using the no-rewind device which will leave the tape sitting at the end of the cpio section. You can then continue on however you want to get the rest of the tape. In my case I used cpio with the 'k' option to skip bad sections and start at the next valid header. I don't know that tar has any such options.. Good luck Randy Jarrett WA4MEI | US SNAIL: 2859 Paces Ferry Rd. UUCP ...!emory!bcs800!rsj | Suite 1000 PHONE +1 404 431 1200 | Atlanta, GA 30339