问如何使用更新(首选) ssh键方便地更新authorized_keys文件，并删除不推荐的密钥

EN

# Filename: ssh-update-key

# Instructions:
# Set the two variables below (deprecated_key, preferred_key).
# Invoke using: ssh-update-key account@someserver.com

### Configuration

# Create ~/.ssh/deprecated directory and move your deprecated key (private and pub) into there.  Then set this variable.
deprecated_key=id_rsa

# Set this variable to your preferred key.  Should be located in ~/.ssh
preferred_key=id_ed25519


### Script 

# create symlink, so that ssh-agent will find and load the deprecated key
# (this happens automatically for me on Ubuntu 20.04)
(cd ~/.ssh && 
ln -s deprecated/$deprecated_key . && 
ln -s deprecated/$deprecated_key.pub . 
)

# copy the preferred key to the remote server
ssh-copy-id -i ~/.ssh/$preferred_key "$@"

# now remove symlinks (only if they are symlinks - don't want an accident)
(cd ~/.ssh &&
 [ -L $deprecated_key ] && rm $deprecated_key &&
 [ -L $deprecated_key.pub ] && rm $deprecated_key.pub
)
# ssh-agent does not reliably remove keys if the files are removed.
# kill it to make sure.  For me on Ubuntu 20.04 it respawns automatically.
killall ssh-agent

# Now remove deprecated key from remote authorized_keys file
# the awk regex escapes / characters which would otherwise mess up sed.
ssh "$@" -o PasswordAuthentication=no "sed -i.bak '/$(awk '{gsub(/\//, "\\/"); print $2}' ~/.ssh/deprecated/$deprecated_key.pub)/d' ~/.ssh/authorized_keys"