3 ms·

If it's a tape archiver, why is it allowed to write to disk? Check and mate.

Annatar 10y ago
tar isn't allowed or disallowed to write to disk -- f specifies a device, and that device just happens to be a file on a filesystem. Since everything on UNIX is a file, even a tape drive, even a huge 6,000 tape silo with 128 tape drives is multiple files under /dev/rmt/, this does not violate the principle. To put this into perspective for you, you could use the block device /dev/dsk/c0t0d0s2 as a tar file to write a tape archive to: tar cvf /some/path /dev/dsk/c0t0d0s2 The manual page for tar clearly states that tar is for tape archive manipulation: BSDTAR(1) BSD General Commands Manual BSDTAR(1) NAME tar -- manipulate tape archives Tape. Your statement is an indication that what you really need is to read AEleen Frisch's Essential System Administration so that the UNIX concepts would sink in, because if you're making such statements, you're just not there yet.
- GFK_of_xmaspast 10y ago
  I've been using unix since 1992, starting with ultrix, then going to sunos, netbsd, solaris, linux, tru64, osx, and I think aix was in there somewhere too.
  - Annatar 10y ago
    But how much have you really learned? And were you an end user or a system administrator? I work with people who have used UNIX for 20-30 years and still don't understand why configuration packages should automatically (re)start a service upon upgrade, stop the service before removal, and start it upon initial install of the configuration package. 30 years of using all kinds of UNIX operating systems and they haven't learned a thing beyond being an end user. And some of these people are developers. So the length of usage isn't crucial, but how much one has learned about the subject -- with an understanding of concepts and ideas behind it. I used all of those you list -- but as my breadth and usage deepened, I sought to understand the principles and ideas behind UNIX.

tar isn't allowed or disallowed to write to disk -- f specifies a device, and that device just happens to be a file on a filesystem. Since everything on UNIX is a file, even a tape drive, even a huge 6,000 tape silo with 128 tape drives is multiple files under /dev/rmt/, this does not violate the principle. To put this into perspective for you, you could use the block device /dev/dsk/c0t0d0s2 as a tar file to write a tape archive to: tar cvf /some/path /dev/dsk/c0t0d0s2 The manual page for tar clearly states that tar is for tape archive manipulation: BSDTAR(1) BSD General Commands Manual BSDTAR(1) NAME tar -- manipulate tape archives Tape. Your statement is an indication that what you really need is to read AEleen Frisch's Essential System Administration so that the UNIX concepts would sink in, because if you're making such statements, you're just not there yet.

GFK_of_xmaspast 10y ago
I've been using unix since 1992, starting with ultrix, then going to sunos, netbsd, solaris, linux, tru64, osx, and I think aix was in there somewhere too.
- Annatar 10y ago
  But how much have you really learned? And were you an end user or a system administrator? I work with people who have used UNIX for 20-30 years and still don't understand why configuration packages should automatically (re)start a service upon upgrade, stop the service before removal, and start it upon initial install of the configuration package. 30 years of using all kinds of UNIX operating systems and they haven't learned a thing beyond being an end user. And some of these people are developers. So the length of usage isn't crucial, but how much one has learned about the subject -- with an understanding of concepts and ideas behind it. I used all of those you list -- but as my breadth and usage deepened, I sought to understand the principles and ideas behind UNIX.