Ubuntu – how to save stderr and stdout to a file in ubuntu

To do that, use one extra file descriptor to switch stderr and stdout:

find /var/log 3>&1 1>&2 2>&3 | tee foo.file

Basically, it works, or at least I think it works, as follows:
The re-directions are evaluated left-to-right.

3>&1 Makes a new file descriptor, 3 a duplicate (copy) of fd 1 (stdout).

1>&2 Make stdout (1) a duplicate of fd 2 (stderr)

2>&3 Make fd 2, a duplicate (copy) of 3, which was previously made a copy of stdout.

So now stderr and stdout are switched.

| tee foo.file tee duplicates file descriptor 1 which was made into stderr.

The first way you invoke the command doesn't create a pty, while the second may or may not. Try telling sshd not to create a pty. In your authorized_keys file:
command="/usr/local/bin/myscript.sh",from="client",no-pty ssh-rsa...

If you want to ssh from the command line when the no-pty option is set in your authorized_keys files you must redirect the STDIN to read from /dev/null or you would get an error saying PTY allocation request failed on channel 0:

$ ssh auto@remoteserver < /dev/null > content.tar.gz

If instead you do the ssh command without a controlling terminal, there's not STDIN available and you can omit the < /dev/null part. So in cron you might do the following without problem:

0 4 * * * ssh auto@remoteserver > content.tar.gz