+ /*
+ ** .pp
+ ** This specifies the operating system name for the \fTUser-Agent:\fP header field. If
+ ** this is \fIunset\fP, it will be set to the operating system name that \fTuname(2)\fP
+ ** returns. If \fTuname(2)\fP fails, ``UNIX'' will be used.
+ ** .pp
+ ** It may, for example, look as: ``\fTMadmutt 1.5.9i (Linux)\fP''.
+ */
+ string_t operating_system = madmutt_init_os();
+