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Our experts answer your technical questions.
Backup Chokes

I use a DDS4 tape drive on a Compaq Alpha (Red Hat 7.1) to back up several filesystems on other Linux workstations (PCs with Red Hat 7.0 and 7.1). I've set up ssh so DSA authentication allows me to run a simple backup script at night via cron, without being prompted for a password. I use tar (gtar version 1.13.17) and dd (GNU fileutils 4.0x) to store the files on tape. Somewhere down the tar/dd combination I get the message:

select: Bad file descriptor

The backup script then stops tar/dd-ing and proceeds normally with the rest of the instructions. What am I missing?

—Martin Olivera,

This error has shown up as a result of a bug in early versions of OpenSSH. The first thing to try is to upgrade ssh on all the systems to the latest stable version.

—Don Marti,


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