Name: signal

Type: message

Syntax: signal <sigNumber> 

Summary: Sent to the <current card> when another <process> sends a kill signal to the <application>.

Associations: card

Introduced: 1.0

OS: mac,linux

Platforms: desktop,server,web

Security: process

Example:
on signal -- let the user know:
  answer warning "Ack! I've been killed by another application!"
end signal

Parameters:
sigNumber: The number of the Unix kill signal (1 for SIGUSR1, 2 for SIGUSR2) that was sent to the application.

Description:
Handle the <signal> message to perform cleanup before an external <process> causes the <application> to <exit>.

The user can execute the Unix "kill" command to send a kill signal to the application. Other processes can use a Unix system call to send a kill signal.

Only signal 1 (SIGUSR1) and signal 2 (SIGUSR2) are supported. Other signals sent to the application do not cause the <signal> <message> to be sent.

Changes:
Support for the signal message on OS X systems was added in version 2.0.

References: kill (command), application (glossary), current card (glossary), message (glossary), process (glossary), exit (control_st)
