This manual page is part of the POSIX Programmer's Manual. The Linux
implementation of this interface may differ (consult the
corresponding Linux manual page for details of Linux behavior), or
the interface may not be implemented on Linux.
These functions shall retrieve information about network services.
This information is considered to be stored in a database that can be
accessed sequentially or randomly. The implementation of this
database is unspecified.
The setservent() function shall open a connection to the database,
and set the next entry to the first entry. If the stayopen argument
is non-zero, the net database shall not be closed after each call to
the getservent() function (either directly, or indirectly through one
of the other getserv*() functions), and the implementation may
maintain an open file descriptor for the database.
The getservent() function shall read the next entry of the database,
opening and closing a connection to the database as necessary.
The getservbyname() function shall search the database from the
beginning and find the first entry for which the service name
specified by name matches the s_name member and the protocol name
specified by proto matches the s_proto member, opening and closing a
connection to the database as necessary. If proto is a null pointer,
any value of the s_proto member shall be matched.
The getservbyport() function shall search the database from the
beginning and find the first entry for which the port specified by
port matches the s_port member and the protocol name specified by
proto matches the s_proto member, opening and closing a connection to
the database as necessary. If proto is a null pointer, any value of
the s_proto member shall be matched. The port argument shall be a
value obtained by converting a uint16_t in network byte order to int.
The getservbyname(), getservbyport(), and getservent() functions
shall each return a pointer to a servent structure, the members of
which shall contain the fields of an entry in the network services
The endservent() function shall close the database, releasing any
open file descriptor.
These functions need not be thread-safe.
Upon successful completion, getservbyname(), getservbyport(), and
getservent() return a pointer to a servent structure if the requested
entry was found, and a null pointer if the end of the database was
reached or the requested entry was not found. Otherwise, a null
pointer is returned.
The application shall not modify the structure to which the return
value points, nor any storage areas pointed to by pointers within the
structure. The returned pointer, and pointers within the structure,
might be invalidated or the structure or the storage areas might be
overwritten by a subsequent call to getservbyname(), getservbyport(),
Portions of this text are reprinted and reproduced in electronic form
from IEEE Std 1003.1, 2013 Edition, Standard for Information
Technology -- Portable Operating System Interface (POSIX), The Open
Group Base Specifications Issue 7, Copyright (C) 2013 by the
Institute of Electrical and Electronics Engineers, Inc and The Open
Group. (This is POSIX.1-2008 with the 2013 Technical Corrigendum 1
applied.) In the event of any discrepancy between this version and
the original IEEE and The Open Group Standard, the original IEEE and
The Open Group Standard is the referee document. The original
Standard can be obtained online at http://www.unix.org/online.html .
Any typographical or formatting errors that appear in this page are
most likely to have been introduced during the conversion of the
source files to man page format. To report such errors, see
IEEE/The Open Group 2013 ENDSERVENT(3P)