(UNIX only) CHAT allows two users to enter into a dialog in which they can type messages back and forth to each other; this is similar to PTCHAT.LIT under PolyTRACK. While in the dialog, their previous instance of A-Shell is put into the background, and automatically restored to the foreground when the dialog is over.

CHAT <target name>

Target name may be either the job name or the login user name of the person you want to chat with; you can use the SYSTAT command to help you determine this information.) The target user will then get a pop-up message on his screen asking him if he wants to engage you in dialog. If not, or if he does not respond within fifteen seconds, the dialog does not take place. While this is happening, the originating user will have been returned to the dot prompt and can go on running another program. If the target user does engage, at that point, a similar phenomenon will happen with the originating user. (A pop-up dialog appears on the screen, suspending the previous process.) Once the dialog begins, it continues until either user exits by hitting the Escape key. At that point, the dialog is closed on both screens and both users go back to the process that was previously running.

Note that because of UNIX security rules, it is impossible for one user to send signals to another unless the first user has superuser privileges, or unless they are both sharing the same effective user ID. Refer to File Ownership and Privileges for instructions on achieving this.