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.Dd January 12, 1994
.Dt GETSERVENT 3
.Os
.Sh NAME
.Nm getservent ,
.Nm getservbyport ,
.Nm getservbyname ,
.Nm setservent ,
.Nm endservent
.Nd get service entry
.Sh SYNOPSIS
.Fd #include <netdb.h>
.Ft struct servent *
.Fn getservent "void"
.Ft struct servent *
.Fn getservbyname "char *name" "char *proto"
.Ft struct servent *
.Fn getservbyport "int port" "char *proto"
.Ft void
.Fn setservent "int stayopen"
.Ft void
.Fn endservent "void"
.Sh DESCRIPTION
The
.Fn getservent ,
.Fn getservbyname ,
and
.Fn getservbyport
functions each return a pointer to an object with the following structure
containing the broken-out fields of a line in the network services database,
.Pa /etc/services .
.Bd -literal -offset indent
struct  servent {
        char    *s_name;        /* official name of service */
        char    **s_aliases;    /* alias list */
        int     s_port;         /* port service resides at */
        char    *s_proto;       /* protocol to use */
};
.Ed
.Pp
The members of this structure are:
.Bl -tag -width s_aliases
.It Fa s_name
The official name of the service.
.It Fa s_aliases
A zero-terminated list of alternate names for the service.
.It Fa s_port
The port number at which the service resides.
Port numbers are returned in network byte order.
.It Fa s_proto
The name of the protocol to use when contacting the service.
.El
.Pp
The
.Fn getservent
function reads the next line of the file, opening the file if necessary.
.Pp
The
.Fn setservent
function opens and rewinds the file.
If the
.Fa stayopen
flag is non-zero,
the net database will not be closed after each call to
.Fn getservbyname
or
.Fn getservbyport .
.Pp
The
.Fn endservent
function closes the file.
.Pp
The
.Fn getservbyname
and
.Fn getservbyport
functions sequentially search from the beginning of the file until a
matching protocol name or port number (specified in network byte order)
is found, or until
.Dv EOF
is encountered.
If a protocol name is also supplied (non-null),
searches must also match the protocol.
.Sh FILES
.Bl -tag -width /etc/services -compact
.It Pa /etc/services
.El
.Sh DIAGNOSTICS
Null pointer (0) returned on
.Dv EOF
or error.
.Sh SEE ALSO
.Xr getprotoent 3 ,
.Xr services 5
.Sh HISTORY
The
.Fn getservent ,
.Fn getservbyport ,
.Fn getservbyname ,
.Fn setservent ,
and
.Fn endservent
functions appeared in
.Bx 4.2 .
.Sh BUGS
These functions use static data storage; if the data is needed for future use,
it should be copied before any subsequent calls overwrite it.
Expecting port numbers to fit in a 32-bit quantity is probably naive.