mirror of https://github.com/mkerrisk/man-pages
212 lines
4.9 KiB
Groff
212 lines
4.9 KiB
Groff
.\" Copyright 1993 David Metcalfe (david@prism.demon.co.uk)
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.\"
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.\" %%%LICENSE_START(VERBATIM)
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.\" Permission is granted to make and distribute verbatim copies of this
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.\" manual provided the copyright notice and this permission notice are
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.\" preserved on all copies.
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.\"
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.\" Permission is granted to copy and distribute modified versions of this
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.\" manual under the conditions for verbatim copying, provided that the
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.\" entire resulting derived work is distributed under the terms of a
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.\" permission notice identical to this one.
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.\"
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.\" Since the Linux kernel and libraries are constantly changing, this
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.\" manual page may be incorrect or out-of-date. The author(s) assume no
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.\" responsibility for errors or omissions, or for damages resulting from
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.\" the use of the information contained herein. The author(s) may not
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.\" have taken the same level of care in the production of this manual,
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.\" which is licensed free of charge, as they might when working
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.\" professionally.
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.\"
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.\" Formatted or processed versions of this manual, if unaccompanied by
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.\" the source, must acknowledge the copyright and authors of this work.
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.\" %%%LICENSE_END
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.\"
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.\" References consulted:
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.\" Linux libc source code
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.\" Lewine's _POSIX Programmer's Guide_ (O'Reilly & Associates, 1991)
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.\" 386BSD man pages
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.\" Modified Sat Jul 24 19:19:11 1993 by Rik Faith (faith@cs.unc.edu)
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.\" Modified Wed Oct 18 20:23:54 1995 by Martin Schulze <joey@infodrom.north.de>
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.\" Modified Mon Apr 22 01:50:54 1996 by Martin Schulze <joey@infodrom.north.de>
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.\" 2001-07-25 added a clause about NULL proto (Martin Michlmayr or David N. Welton)
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.\"
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.TH GETSERVENT 3 2021-03-22 "GNU" "Linux Programmer's Manual"
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.SH NAME
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getservent, getservbyname, getservbyport, setservent, endservent \-
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get service entry
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.SH SYNOPSIS
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.nf
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.B #include <netdb.h>
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.PP
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.B struct servent *getservent(void);
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.PP
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.BI "struct servent *getservbyname(const char *" name ", const char *" proto );
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.BI "struct servent *getservbyport(int " port ", const char *" proto );
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.PP
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.BI "void setservent(int " stayopen );
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.B void endservent(void);
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.fi
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.SH DESCRIPTION
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The
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.BR getservent ()
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function reads the next entry from the services database (see
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.BR services (5))
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and returns a
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.I servent
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structure containing
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the broken-out fields from the entry.
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A connection is opened to the database if necessary.
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.PP
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The
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.BR getservbyname ()
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function returns a
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.I servent
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structure
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for the entry from the database
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that matches the service
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.I name
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using protocol
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.IR proto .
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If
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.I proto
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is NULL, any protocol will be matched.
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A connection is opened to the database if necessary.
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.PP
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The
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.BR getservbyport ()
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function returns a
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.I servent
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structure
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for the entry from the database
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that matches the port
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.I port
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(given in network byte order)
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using protocol
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.IR proto .
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If
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.I proto
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is NULL, any protocol will be matched.
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A connection is opened to the database if necessary.
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.PP
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The
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.BR setservent ()
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function opens a connection to the database,
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and sets the next entry to the first entry.
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If
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.I stayopen
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is nonzero,
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then the connection to the database
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will not be closed between calls to one of the
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.BR getserv* ()
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functions.
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.PP
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The
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.BR endservent ()
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function closes the connection to the database.
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.PP
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The
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.I servent
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structure is defined in
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.I <netdb.h>
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as follows:
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.PP
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.in +4n
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.EX
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struct servent {
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char *s_name; /* official service name */
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char **s_aliases; /* alias list */
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int s_port; /* port number */
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char *s_proto; /* protocol to use */
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}
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.EE
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.in
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.PP
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The members of the
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.I servent
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structure are:
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.TP
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.I s_name
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The official name of the service.
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.TP
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.I s_aliases
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A NULL-terminated list of alternative names for the service.
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.TP
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.I s_port
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The port number for the service given in network byte order.
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.TP
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.I s_proto
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The name of the protocol to use with this service.
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.SH RETURN VALUE
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The
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.BR getservent (),
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.BR getservbyname (),
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and
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.BR getservbyport ()
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functions return a pointer to a
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statically allocated
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.I servent
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structure, or NULL if an
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error occurs or the end of the file is reached.
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.SH FILES
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.TP
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.I /etc/services
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services database file
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.SH ATTRIBUTES
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For an explanation of the terms used in this section, see
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.BR attributes (7).
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.ad l
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.nh
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.TS
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allbox;
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lb lb lbx
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l l l.
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Interface Attribute Value
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T{
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.BR getservent ()
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T} Thread safety T{
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MT-Unsafe race:servent
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race:serventbuf locale
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T}
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T{
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.BR getservbyname ()
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T} Thread safety T{
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MT-Unsafe race:servbyname
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locale
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T}
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T{
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.BR getservbyport ()
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T} Thread safety T{
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MT-Unsafe race:servbyport
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locale
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T}
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T{
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.BR setservent (),
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.BR endservent ()
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T} Thread safety T{
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MT-Unsafe race:servent
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locale
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T}
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.TE
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.hy
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.ad
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.sp 1
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In the above table,
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.I servent
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in
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.I race:servent
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signifies that if any of the functions
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.BR setservent (),
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.BR getservent (),
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or
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.BR endservent ()
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are used in parallel in different threads of a program,
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then data races could occur.
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.SH CONFORMING TO
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POSIX.1-2001, POSIX.1-2008, 4.3BSD.
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.SH SEE ALSO
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.BR getnetent (3),
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.BR getprotoent (3),
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.BR getservent_r (3),
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.BR services (5)
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