.TH PRECEIVE 2 .SH NAME preceive \- get a message from a port .SH SYNOPSIS .nf .B char *preceive(portid) .B int portid; .fi .SH DESCRIPTION .I Preceive retrieves the next message from the port .I portid, returning a pointer to the message if successful, or SYSERR if .I portid is invalid. (The sender and receiver must agree on a convention for passing the message length.) .PP The calling process is blocked if there are no messages available (and reawakened as soon as a message arrives). The only ways to be released from a port queue are for some other process to send a message to the port with PSEND(2) or for some other process to delete or reset the port with PDELETE(2) or PRESET(2). .SH SEE ALSO pcount(2), pcreate(2), pdelete(2), preset(2), psend(2)