mail command of unix - perl

Question

I am using the mail command of unix in a perl script. I specify the 'to', 'cc', 'subject' and 'body' of the mail. I do not specify the from address. Where is the from address picked from? Pls help

Answer 1

There are portable libraries for handling email as daxim and David W mention, but if you want a quick fix, this works under linux if your mail command uses bsd-mailx (as it does on my machine)...
#!/usr/bin/env perl
$BODY = "Hello self";
$RECIPIENT = "destination\#email.local";
$FROM = "mike\#localhost";
$SUBJECT = "some subject here";
$CMD = qq(echo "$BODY" | mail -a "From: $FROM" -s $SUBJECT $RECIPIENT);
exec($CMD);
If you have more questions about the unix mail command, try man mail from your shell prompt.

Answer 2

The mail command on most system nowadays is Heirloom mailx. It claims compatibility with POSIX, so the information I give here should be good for any well-behaving mail command.
The From address is set by:
either the user#domain as returned by the appropriate POSIX system calls (see shell commands whoami and domainname -f for a different way to access them)
or set by the from environment variable
or set by the -r command line option (going to be deprecated?)
Obligatory Clippy: Hi! I see you are trying to send mail from Perl. Did you mean to use Email::Sender/Email::Simple instead?

Answer 3

Don't use the mail command linecommand! Use Net::SMTP.
The mail command may not even be configured on a particular system, and it won't work on Windows. Meanwhile, Net::SMTP is a standard Perl module that should be available on all systems.
Never used it before? Read the documentation and try it out. That's how you learn.