tcflush (BPX1TFH, BPX4TFH) — Flush input or output on a terminal
Function
The tcflush callable service flushes all data that is sent to a device. Depending on the value of the Queue_selector parameter, any data written, but not sent, or any data received, but not read, is discarded.
Requirements
Operation | Environment |
---|---|
Authorization: | Supervisor or problem state, any PSW key |
Dispatchable unit mode: | Task |
Cross memory mode: | PASN = HASN |
AMODE (BPX1TFH): | 31-bit |
AMODE (BPX4TFH): | 64-bit |
ASC mode: | Primary mode |
Interrupt status: | Enabled for interrupts |
Locks: | Unlocked |
Control parameters: | All parameters must be addressable by the caller and in the primary address space. |
Format
|
AMODE 64 callers use BPX4TFH with the same parameters.
Parameters
- File_descriptor
- Supplied parameter
- Type:
- Integer
- Length:
- Fullword
The name of a fullword that contains the file descriptor of the terminal.
- Queue_selector
- Supplied parameter
- Type:
- Integer
- Length:
- Fullword
The name of a fullword that specifies the queues that are to be flushed. The constants are mapped in the BPXYTIOS macro; see BPXYTIOS — Map the termios structure.Constant Description TCIFLUSH Flush data received but not read TCOFLUSH Flush data written but not sent TCIOFLUSH Flush both data received but not read and data written but not sent - Return_value
- Returned parameter
- Type:
- Integer
- Length:
- Fullword
The name of a fullword in which the tcflush service returns 0 if the request is successful, or -1 if it is not successful.
- Return_code
- Returned parameter
- Type:
- Integer
- Length:
- Fullword
The name of a fullword in which the tcflush service stores the return code. The tcflush service returns Return_code only if Return_value is -1. See z/OS UNIX System Services Messages and Codes for a complete list of possible return code values. The tcflush service can return one of the following values in the Return_code parameter:Return_code Explanation EBADF File_descriptor is not a valid open file descriptor. EINTR A signal interrupted the call. EINVAL The Queue_selector specified was incorrect. EIO The process group of the process that is issuing the function is an orphaned, background process group, and the process that is issuing the function is not ignoring or blocking SIGTTOU. ENOTTY The file that is associated with the file descriptor is not a terminal. - Reason_code
- Returned parameter
- Type:
- Integer
- Length:
- Fullword
The name of a fullword in which the tcflush service stores the reason code. The tcflush service returns Reason_code only if Return_value is -1. Reason_code further qualifies the Return_code value. For the reason codes, see z/OS UNIX System Services Messages and Codes.
Usage notes
The following table defines the processing of the SIGTTOU signal when tcflush is called from a background process against a controlling terminal:
SIGTTOU processing | Expected behavior |
---|---|
Default or signal handler | The SIGTTOU signal is generated. |
Ignored or blocked | The SIGTTOU signal is not sent. |
Related services
Characteristics and restrictions
There are no restrictions on the use of the tcflush service.
Examples
For an example using this callable service, see BPX1TFH (tcflush) example.