Functions and CALL Routines under OpenVMS

TTCONTRL Function: OpenVMS

Modifies the characteristics of a channel that was previously assigned by TTOPEN.

Category:	Terminal-Access
OpenVMS specifics:	All aspects are host-specific

Syntax
Details
Example
See Also

Syntax

TTCONTRL(control-specification,channel)

control-specification: is the control string as described for the TTOPEN function. The syntax for control-specification is the same as for TTOPEN, except that the DEVICE= attribute cannot be changed. The new characteristics take effect on the next I/O operation.
channel: is the channel variable that was returned from the TTOPEN function.

Details

If the TTCONTRL function executes successfully, the return value is 0. Otherwise, the return value is the OpenVMS error code that indicates why it failed.

Example

The following example prompts the user for the password, reads the password (without echoing it to the terminal), and then writes out the password. The last step closes the channel:

length string $ 80;
input='   ';
chan=0;
rc=ttopen("device=tt echo",chan);
rc=ttwrite(chan,"0D0A"X||"Enter password: ");
rc=ttcontrl("noecho",chan);
rc=ttread(chan,input);
rc=ttcontrl("echo",chan);
rc=ttwrite(chan,"0D0A"X||"Password was: "||input);
rc=ttclose(chan);