[linux] How to change sender name (not email address) when using the linux mail command for autosending mail?

It depends on what sender address you are talking about. The sender address visble in the recipients mailprogramm is extracted from the "From:" Header. which can probably easily be set from your program.

If you are talking about the SMTP envelope sender address, you can pass the -f argument to the sendmail binary. Depending on the server configuration you may not be allowed to do that with the apache user.

from the sendmail manpage :

   -f <address>
                 This  option  sets  the  address  of the envelope sender of a
                 locally-generated message (also known as  the  return  path).
                 The  option  can normally be used only by a trusted user, but
                 untrusted_set_sender can be set to allow untrusted  users  to
                 use it. [...]