Manpages - getservent.3

getservent, getservbyname, getservbyport, setservent, endservent - get service entry

  #include <netdb.h>

  struct servent *getservent(void);

  struct servent *getservbyname(const char *name, const char *proto);
  struct servent *getservbyport(int port, const char *proto);

  void setservent(int stayopen);
  void endservent(void);

The *getservent*() function reads the next entry from the services database (see *services*(5)) and returns a servent structure containing the broken-out fields from the entry. A connection is opened to the database if necessary.

The *getservbyname*() function returns a servent structure for the entry from the database that matches the service name using protocol proto. If proto is NULL, any protocol will be matched. A connection is opened to the database if necessary.

The *getservbyport*() function returns a servent structure for the entry from the database that matches the port port (given in network byte order) using protocol proto. If proto is NULL, any protocol will be matched. A connection is opened to the database if necessary.

The *setservent*() function opens a connection to the database, and sets the next entry to the first entry. If stayopen is nonzero, then the connection to the database will not be closed between calls to one of the *getserv**() functions.

The *endservent*() function closes the connection to the database.

The servent structure is defined in <netdb.h> as follows:

  struct servent {
      char  *s_name;       /* official service name */
      char **s_aliases;    /* alias list */
      int    s_port;       /* port number */
      char  *s_proto;      /* protocol to use */
  }

The members of the servent structure are:

s_name

The official name of the service.

s_aliases

A NULL-terminated list of alternative names for the service.

s_port

The port number for the service given in network byte order.

s_proto

The name of the protocol to use with this service.

The *getservent*(), *getservbyname*(), and *getservbyport*() functions return a pointer to a statically allocated servent structure, or NULL if an error occurs or the end of the file is reached.

/etc/services

services database file

For an explanation of the terms used in this section, see *attributes*(7).

In the above table, servent in race:servent signifies that if any of the functions *setservent*(), *getservent*(), or *endservent*() are used in parallel in different threads of a program, then data races could occur.

POSIX.1-2001, POSIX.1-2008, 4.3BSD.

*getnetent*(3), *getprotoent*(3), *getservent_r*(3), *services*(5)

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