A process executes or "execs" another process on a channel via an irExec(3IRAPI) function. Channels may be irExec'd to permanent or transient processes. Permanent process are typically multi-channel applications run from inittab. Transient processes are exec(2)'d by the irExec function and typically exit(2) when the call, or their portion of it, completes.

Ownership of the channel is relinquished by the current owner with an irExec. Once an irExec function is called, the calling process must stop using the channel_id. As was discussed earlier, AD irExec's channels based on application assignments.

Channel ownership is made available immediately to the irExec'd application. After receiving the IRE_EXEC event, the channel should be initialized immediately via irInit(3IRAPI).

Parameters may be used to allow the child process to run in a context similar to the parent process. Also, the following parameters may be used to allow the parent process to pass data to the child process:

• IRP_EXEC_BUF is a data buffer that is not interpreted by the IRAPI. A parent process sets this buffer and its length through irExec(3IRAPI) arguments. The child application then accesses the data via irGetParamStr(3IRAPI).
• The parameter IRP_REGISTER allows data to be passed similar to IRP_EXEC_BUF; however, there is not a length parameter associated with IRP_REGISTER and parent processes must set explicitly the parameter via irSetParamStr(3IRAPI).

Many IRAPI parameters and parameter values are saved across irExec boundaries. Any resources explicitly allocated by irReserveResource(3IRAPI) are saved across irExec boundaries. Half bridges [irHBridge(3IRAPI)] remain active across irExec boundaries. Echo cancellation [irEcho(3IRAPI)] remains on.

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