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Re: [vox-tech] crontab and scp puzzle
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Re: [vox-tech] crontab and scp puzzle

I know I've used this answer before on this list, and I'm sure it's annoying, but if your solution involves passphraseless ssh keys, you're doing it wrong.

That being said, since cron is a daemon, it is not attached to a controlling terminal. That means that a script that expects to be able to read input from the user is going to fail. You can probably force it to bypass this code with BatchMode.

    ssh -o BatchMode=yes ...

For good measure, you could even set TERM if it's not being set.

    env TERM=dumb ssh -o BatchMode=yes ...

On Wed, Mar 16, 2011 at 9:43 AM, Bruce Wolk <bawolk@ucdavis.edu> wrote:
I need to copy a file from my server to a workstation on a regular
basis.  I have set up passwordless ssh access to the server from my
workstation.  When I execute the following on the workstation, the
command succeeds and the file is copied:

scp -P 33303 bruce@myserver.com:backup/db.sql.gz

But when I put the same command into a cron file on the workstation, the
command fails.  The relevant output from the scp command is:

debug1: Found key in /home/bruce/.ssh/known_hosts:5
debug1: ssh_rsa_verify: signature correct
debug1: SSH2_MSG_NEWKEYS sent
debug1: expecting SSH2_MSG_NEWKEYS
debug1: SSH2_MSG_NEWKEYS received
debug1: Roaming not allowed by server
debug1: SSH2_MSG_SERVICE_ACCEPT received
debug1: Authentications that can continue: publickey
debug1: Next authentication method: publickey
debug1: Offering public key: /home/bruce/.ssh/id_rsa.pub
debug1: Server accepts key: pkalg ssh-rsa blen 279
debug1: PEM_read_PrivateKey failed
debug1: read PEM private key done: type <unknown>
debug1: read_passphrase: can't open /dev/tty: No such device or address
debug1: No more authentication methods to try.
Permission denied (publickey).

I edited the cron file using crontab -e and have verified that it is
excecuting properly as user bruce.

I googled around but found nothing that helps.  Why would the
authentication work with direct execution, but fail with cron execution?
 Does anyone have any ideas?

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