mail

Local notifications via mail spool (typically for system messages or scripts). It provides simple email interface for users on the same system.

Check Mail

mail

It lists the mail by reading your spool file in /var/mail/<username>.

Useful mail commands at the & promt

  • 8 - Read a specific message number; 1-n.
  • d - Delete the current message | current read message
  • q - Quit and save your read mail; moves read messages out of your inbox
  • n - Reads the next message
  • p - Print the current message; re-read the mail
  • h - Show the message headers list.

Send Mail to Another User

echo "This is body when using this command" | mail -s "Subject" iamyaash
echo "Backup completed successfully." | mail -s "Backup Status" adminuser

df -h | mail -s "Disk Usage Report:" iamyaash

You can also use just mail username, then type a subject and body, finishing it with CTRL+D.

wall

Display a message to all the currently logged in users. It’s mostly used for quick system-wide announcements and only root or users with elevated privileges can broadcast.

Broadcast a message

Single line message:

wall "This system will reboot in 8 minutes."

Multi-line message:

wall
<type your message>
(Press CTRL+D to send & exit)

write

It sends real-time messages to another user who is currently logged-in on the same system. Both uses must be logged in, since it’s a real-time messaging tool it won’t store the message for reading it later. In simple terms, it’s not persistent like mail.

Can estalish communication only when the two users are online at the same time.

Find who is logged in

who # to see who is currently logged-in
w # see wee what they are doing

Send a message

write iamyaash

Throw an error, when the user who is sending the message don’t have elevated privileges:

iamyaash@pi5:~ $ write hugo-pages pts/1 
write: effective gid does not match group of /dev/pts/0

Make sure to use sudo, when lacking privileges:

# sender
iamyaash@pi5:~ $ sudo write hugo-pages pts/1 
this is testing!

# receiver
hugo-pages@pi5:~ $ 
Message from iamyaash@pi5 (as root) on pts/2 at 00:22 ...
this is testing!
EOF