scp host key verification failed when executed by php

Question

I'm trying to use scp to copy files. I use the command shell_exec of PHP to execute this command:

scp -i/home/raul/nueva_clave -q -v /home/raul/www/CA/app/tmp/ImagenWeb [email protected]:/home/TA-adm/images/IMG_3846.JPG 2>&1

The server address is 127.0.0.1 because I'm still developing the script. I'll change it later.

I'm using scp instead of ssh2_scp_send of PHP because I don't want to write the password of the server in my proyect. Instead og that I'd like to use a public key. But when I execute in PHP this is the result:

Executing: program /usr/bin/ssh host 127.0.0.1, user TA-adm, command scp -v -t -- /home/TA-adm/images/IMG_3846.JPG
OpenSSH_5.9p1 Debian-5ubuntu1, OpenSSL 1.0.1 14 Mar 2012
debug1: Reading configuration data /etc/ssh/ssh_config
debug1: /etc/ssh/ssh_config line 19: Applying options for *
debug1: Connecting to 127.0.0.1 [127.0.0.1] port 22.
debug1: Connection established.
debug1: SELinux support disabled
Could not create directory '/nonexistent/.ssh'.
debug1: identity file /home/raul/nueva_clave type 1
debug1: Checking blacklist file /usr/share/ssh/blacklist.RSA-2048
debug1: Checking blacklist file /etc/ssh/blacklist.RSA-2048
debug1: identity file /home/raul/nueva_clave-cert type -1
debug1: Remote protocol version 2.0, remote software version OpenSSH_5.9p1 Debian-5ubuntu1
debug1: match: OpenSSH_5.9p1 Debian-5ubuntu1 pat OpenSSH*
debug1: Enabling compatibility mode for protocol 2.0
debug1: Local version string SSH-2.0-OpenSSH_5.9p1 Debian-5ubuntu1
debug1: SSH2_MSG_KEXINIT sent
debug1: SSH2_MSG_KEXINIT received
debug1: kex: server->client aes128-ctr hmac-md5 none
debug1: kex: client->server aes128-ctr hmac-md5 none
debug1: sending SSH2_MSG_KEX_ECDH_INIT
debug1: expecting SSH2_MSG_KEX_ECDH_REPLY
debug1: Server host key: ECDSA 2d:71:67:30:89:c0:1a:64:41:b5:07:8f:6d:c5:9f:13
debug1: read_passphrase: can't open /dev/tty: No such device or address
Host key verification failed.
lost connection

If I execute this command with my user in the terminal I have no problems. I suppose that the problem is that the user nobody is executing the scp. I'm using Ubuntu.

Answer 1

(Answered by the OP in a question edit. Moved here. See Question with no answers, but issue solved in the comments (or extended in chat) )

The OP wrote:

It's SOLVED. I've used the options:

-o UserKnownHostsFile=/dev/null -o StrictHostKeyChecking=no

so the scp command doesn't try to insert the host in the file known_host file of the user nobody (scp can't create the file because the user nobody has no home neither ~/.ssh).