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[thirdparty/man-pages.git] / man3 / getservent.3

.\" Copyright 1993 David Metcalfe (david@prism.demon.co.uk)
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.\" References consulted:
.\"     Linux libc source code
.\"     Lewine's _POSIX Programmer's Guide_ (O'Reilly & Associates, 1991)
.\"     386BSD man pages
.\" Modified Sat Jul 24 19:19:11 1993 by Rik Faith (faith@cs.unc.edu)
.\" Modified Wed Oct 18 20:23:54 1995 by Martin Schulze <joey@infodrom.north.de>
.\" Modified Mon Apr 22 01:50:54 1996 by Martin Schulze <joey@infodrom.north.de>
.\" 2001-07-25 added a clause about NULL proto (Martin Michlmayr or David N. Welton)
.\"
.TH GETSERVENT 3  2001-07-25 "GNU" "Linux Programmer's Manual"
.SH NAME
getservent, getservbyname, getservbyport, setservent, endservent \-
get service entry
.SH SYNOPSIS
.nf
.B #include <netdb.h>
.sp
.B struct servent *getservent(void);
.sp
.BI "struct servent *getservbyname(const char *" name ", const char *" proto );
.sp
.BI "struct servent *getservbyport(int " port ", const char *" proto );
.sp
.BI "void setservent(int " stayopen );
.sp
.B void endservent(void);
.fi
.SH DESCRIPTION
The
.BR getservent ()
function reads the next line from the file
\fI/etc/services\fP and returns a structure \fIservent\fP containing
the broken out fields from the line.
The \fI/etc/services\fP file
is opened if necessary.
.PP
The
.BR getservbyname ()
function returns a \fIservent\fP structure
for the line from \fI/etc/services\fP that matches the service
\fIname\fP using protocol \fIproto\fP.
If \fIproto\fP is NULL, any protocol will be matched.
.PP
The
.BR getservbyport ()
function returns a \fIservent\fP structure
for the line that matches the port \fIport\fP given in network byte order
using protocol \fIproto\fP.
If \fIproto\fP is NULL, any protocol will be matched.
.PP
The
.BR setservent ()
function opens and rewinds the
\fI/etc/services\fP file.
If \fIstayopen\fP is true (1), then the
file will not be closed between calls to
.BR getservbyname ()
and
.BR getservbyport ().
.PP
The
.BR endservent ()
function closes \fI/etc/services\fP.
.PP
The \fIservent\fP structure is defined in \fI<netdb.h>\fP as follows:
.sp
.RS 4
.nf
struct servent {
    char  *s_name;       /* official service name */
    char **s_aliases;    /* alias list */
    int    s_port;       /* port number */
    char  *s_proto;      /* protocol to use */
}
.fi
.RE
.PP
The members of the \fIservent\fP structure are:
.TP
.I s_name
The official name of the service.
.TP
.I s_aliases
A zero terminated list of alternative names for the service.
.TP
.I s_port
The port number for the service given in network byte order.
.TP
.I s_proto
The name of the protocol to use with this service.
.SH "RETURN VALUE"
The
.BR getservent (),
.BR getservbyname ()
and
.BR getservbyport ()
functions return the \fIservent\fP structure, or a NULL pointer if an
error occurs or the end of the file is reached.
.SH FILES
.TP
.I /etc/services
services database file
.SH "CONFORMING TO"
4.3BSD, POSIX.1-2001.
.SH "SEE ALSO"
.BR getnetent (3),
.BR getprotoent (3),
.BR services (5)