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PROLOG | NAME | SYNOPSIS | DESCRIPTION | RETURN VALUE | ERRORS | EXAMPLES | APPLICATION USAGE | RATIONALE | FUTURE DIRECTIONS | SEE ALSO | COPYRIGHT |
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ENDSERVENT(3P) POSIX Programmer's Manual ENDSERVENT(3P)
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.
endservent, getservbyname, getservbyport, getservent, setservent —
network services database functions
#include <netdb.h>
void endservent(void);
struct servent *getservbyname(const char *name, const char *proto);
struct servent *getservbyport(int port, const char *proto);
struct servent *getservent(void);
void setservent(int stayopen);
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
database.
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(), or getservent(). The returned
pointer, and pointers within the structure, might also be
invalidated if the calling thread is terminated.
No errors are defined.
The following sections are informative.
None.
The port argument of getservbyport() need not be compatible with
the port values of all address families.
None.
None.
endhostent(3p), endprotoent(3p), htonl(3p), inet_addr(3p)
The Base Definitions volume of POSIX.1‐2017, netdb.h(0p)
Portions of this text are reprinted and reproduced in electronic
form from IEEE Std 1003.1-2017, Standard for Information
Technology -- Portable Operating System Interface (POSIX), The
Open Group Base Specifications Issue 7, 2018 Edition, Copyright
(C) 2018 by the Institute of Electrical and Electronics Engineers,
Inc and The Open Group. 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.opengroup.org/unix/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
https://www.kernel.org/doc/man-pages/reporting_bugs.html .
IEEE/The Open Group 2017 ENDSERVENT(3P)
Pages that refer to this page: netdb.h(0p), endhostent(3p), freeaddrinfo(3p), getnameinfo(3p), getservbyname(3p), htonl(3p), setservent(3p)
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HTML rendering created 2025-09-06 by Michael Kerrisk, author of The Linux Programming Interface. For details of in-depth Linux/UNIX system programming training courses that I teach, look here. Hosting by jambit GmbH. |
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