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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 

.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.