Copying local SSH key to remote host if it doesn't exist already
Just use a variable, like this:
KEY=$(cat ~/.ssh/id_rsa.pub) ssh -p <port> <user>@<hostname> "if [ -z \"\$(grep \"$KEY\" ~/.ssh/authorized_keys )\" ]; then echo $KEY >> ~/.ssh/authorized_keys; echo key added.; fi;"
Why not just use ssh-copy-id?
NAME
ssh-copy-id -- copy public keys to a remote host
SYNOPSIS
ssh-copy-id [-lv] [-i keyfile] [-o option] [-p port] [user@]hostname
DESCRIPTION
The ssh-copy-id utility copies public keys to a remote host's ~/.ssh/authorized_keys file (creating the file and directory, if required). The following options are available: -i file Copy the public key contained in file. This option can be speci- fied multiple times and can be combined with the -l option. If a private key is specified and a public key is found then the pub- lic key will be used. -l Copy the keys currently held by ssh-agent(1). This is the default if the -i option was not specified. -o ssh-option Pass this option directly to ssh(1). This option can be speci- fied multiple times. -p port Connect to the specified port on the remote host instead of the default. -v Pass -v to ssh(1). The remaining arguments are a list of remote hosts to connect to, each one optionally qualified by a user name.
EXIT STATUS
The ssh-copy-id utility exits 0 on success, and >0 if an error occurs.
EXAMPLES
To send a specific key to multiple hosts: $ ssh-copy-id -i /path/to/keyfile.pub user@host1 user@host2 user@host3
Old question maybe, but you can also execute:
ssh -q -o "BatchMode=yes" user@hostname exit
Which if ssh-copy-id already happend will succeed and return 0. If not return an error.