Generate public/private keypair and output to stdout

generate-keypair.sh

#!/bin/bash

BITS=2048

# In one line:
# rm -f temp.key && ssh-keygen -t rsa -b 2048 -f temp.key -N "" -q && ssh-keygen -e -f temp.key -m PKCS8 | tr "\n" " " && echo && cat temp.key | tr "\n" " " && echo

# In multiple lines:
rm -f temp.key
ssh-keygen -t rsa -b $BITS -f temp.key -N "" -q
echo
ssh-keygen -e -f temp.key -m PKCS8 | tr "\n" " "
echo
echo
cat temp.key | tr "\n" " "
echo
echo

Here's a practical example of this for encrypting the ssh key with sops and age in a taskfile:

version: "3"

gen-key:
  desc: Generate encrypted ssh key
  silent: true
  status:
    - test -f ssh.sops.key
  cmds:
    - mkfifo key key.pub
    - defer: rm key key.pub
    - cat key | sops -e /dev/stdin > ssh.sops.key &
    - 'printf "Your public key:\n$(cat key.pub)\n" &'
    - yes | ssh-keygen -t ed25519 -f key > /dev/null