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From: @(#)getservent.3 8.3 (Berkeley) 1/12/94
$FreeBSD$
.Dd July 9, 1995 .Dt GETSERVENT 3 .Os .Sh NAME .Nm getservent , .Nm getservbyport , .Nm getservbyname , .Nm setservent , .Nm endservent .Nd get service entry .Sh LIBRARY .Lb libc .Sh SYNOPSIS n netdb.h .Ft struct servent * .Fn getservent .Ft struct servent * .Fn getservbyname "const char *name" "const char *proto" .Ft struct servent * .Fn getservbyport "int port" "const char *proto" .Ft void .Fn setservent "int stayopen" .Ft void .Fn endservent void .Sh DESCRIPTION The .Fn getservent , .Fn getservbyname , and .Fn getservbyport functions each return a pointer to an object with the following structure containing the broken-out fields of a line in the network services data base,
a /etc/services . d -literal -offset indent struct servent { char *s_name; /* official name of service */ char **s_aliases; /* alias list */ int s_port; /* port service resides at */ char *s_proto; /* protocol to use */ }; .Ed
p The members of this structure are: l -tag -width s_aliases t Fa s_name The official name of the service. t Fa s_aliases A zero terminated list of alternate names for the service. t Fa s_port The port number at which the service resides. Port numbers are returned in network byte order. t Fa s_proto The name of the protocol to use when contacting the service. .El
p The .Fn getservent function reads the next line of the file, opening the file if necessary.
p The .Fn setservent function opens and rewinds the file. If the .Fa stayopen flag is non-zero, the net data base will not be closed after each call to .Fn getservbyname or .Fn getservbyport .
p The .Fn endservent function closes the file.
p The .Fn getservbyname and .Fn getservbyport functions sequentially search from the beginning of the file until a matching protocol name or port number (which must be specified in network byte order) is found, or until .Dv EOF is encountered. If a protocol name is also supplied (non- .Dv NULL ) , searches must also match the protocol. .Sh FILES l -tag -width /etc/services -compact t Pa /etc/services .El .Sh DIAGNOSTICS Null pointer returned on .Dv EOF or error. .Sh SEE ALSO .Xr getprotoent 3 , .Xr services 5 .Sh HISTORY The .Fn getservent , .Fn getservbyport , .Fn getservbyname , .Fn setservent , and .Fn endservent functions appeared in x 4.2 . .Sh BUGS These functions use a thread-specific data storage; if the data is needed for future use, it should be copied before any subsequent calls overwrite it. Expecting port numbers to fit in a 32 bit quantity is probably naive.