Obtain the server certificate for offlineimap. Takes server as first argument, optional second argument for port.

get-certificate-signature.sh

!/bin/bash

## The first argument is the server
## the second [optional] argument is the port, default is 993. 

server=$1
port=${2:-993}
SSL_CERT_DIR=""

openssl s_client -connect $server:$port </dev/null 2>/dev/null | openssl x509 -fingerprint -noout -text -in /dev/stdin | grep "^SHA1 Fingerprint=" | awk -F"=" '{split($2,a," ");gsub(/"/, "", a[1]);print a[1]}' | sed 's/://g' | xclip

echo "The certificate signature is now on the clipboard."