$ curl cheat.sh/
# mail
# The command operates on the user's mailbox if no argument is given.
# To send an email the message body is built from standard input.
# More information: <https://manned.org/mail>.

# Send a typed email message. The command-line below continues after pressing Enter key. Input CC email-id (optional) press Enter key. Input message text (can be multiline). Press Ctrl-D key to complete the message text:
mail --subject="subject line" to_user@example.com

# Send an email that contains file content:
mail --subject="$HOSTNAME filename.txt" to_user@example.com < path/to/filename.txt

# Send a `tar.gz` file as an attachment:
tar cvzf - path/to/directory1 path/to/directory2 | uuencode data.tar.gz | mail --subject="subject_line" to_user@example.com

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