Predefined Per-Thread Variables

Always initialized to the default for each new child thread:

Name	Default	Use
<		A synonym for the getline variable.
@		A synonym for the stmtnumber variable.
child	0	Identification number of the last child process spawned.
echoinput	0	Copy the input to stdout as it’s read. (Similar to echoallinput but not inherited to a child thread.)
eofgetline	0	Pseudo-variable to indicate if the last reference to getline encountered an end-of-file condition.
getchar		Read one character from stdin without echoing. If stdin is tied to the keyboard, outboard keys are returned as two-character strings.
getline		Read one line from stdin pseudo-variable. If stdin is tied to the keyboard, keystrokes are echoed as they’re typed.
history	0	Number of statements to remember on the history list; 0 turns off the history mechanism. (If the thread is interactive, history is automatically set to 100.)
ignoreeof	0	If True, don’t exit at EOF on stdin; insist on an exit command.
ignoreerrors	0	Determine whether execution should continue if an error occurs: 0 means the thread exits; 1 (the default for an interactive thread) means exit from loops or procedures and try to read a new command; 2 means ignore all errors.
ignorestatus	1	If True, a non-zero status code from a child process is ignored. Otherwise, it’s an error.
interactive	0	If True, prompt for input.
irqmask	0	Determines whether interrupts are enabled (0), deferred until the mask is cleared again (1) or ignored (2).
scriptname		Name of the C shell script file being executed, if any.
status	0	Exit code of the last child process.
stmtnumber	1	Autoincremented statement number used with the history list and in prompting.
threadid		Thread id of the currently executing thread.

Each new thread is initialized with default on-interrupt processing (a forced exit), and null search and replace strings.