man from (Commandes) - from

NAME

from - print names of those who have sent mail

[-c] [-s sender] [-f file] [user]

The utility prints out the mail header lines from the invoker's mailbox.

The following options are available:

-c: Just print a count of messages and exit.
-f file: The supplied file is examined instead of the invoker's mailbox. If the -f option is used, the user argument should not be used. Read from standard input if file name - is given.
-s sender: Only mail from addresses containing the supplied string are printed.

If user is given, the user Ns 's mailbox is examined instead of the invoker's own mailbox. (Privileges are required.)

MAIL: If set, the location of the invoker's mailbox. Otherwise, the default in /var/mail is used.

The command appeared in