If you want to attach a file in mutt from command line : echo "Body of email" | mutt -a attach.txt -s "subject" user@gmail.com -a : please provide the full path for attachment.
If you want to attach a file in mutt from command line : echo "Body of email" | mutt -a attach.txt -s "subject" user@gmail.com -a : please provide the full path for attachment.