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3.10. Automatic Setups for Different Terminals

If you work at several kinds of terminals or terminal emulators, terminal setup can be tough. For instance, my X terminal sends a backspace character when I push the upper-right key, but the same key on another terminal sends a delete character -- I want stty erase (Section 5.8) to set the correct erase character automatically.[7] Maybe you want a full set of calendar programs started when you log in to the terminal at your desk, but not when you make a quick login from somewhere else.

[7]Of course, it is all arbitrary and contingent on your keyboard layout and configuration.

The next seven articles have ideas for changing your login sequence automatically. Some examples are for the C shell and use that shell's switch and if. Examples for Bourne-type shells use case (Section 35.10) and if (Section 35.13). If you use the other type of shell, the idea still applies; just swap the syntax.

  • If you use several kinds of terminals or terminal emulators, try testing the TERM environment variable (Section 3.11). Testing other environment variables (Section 3.14) can identify the frontend system (like a window system) you're using.

  • Test the output of who am i (Section 3.12) to find out about the remote system from which you've logged in.

  • If you log into different kinds of ports -- network, hardwired, and so on -- search for the port type (Section 3.15) in a table like /etc/ttys (in BSD derivatives) or /etc/inittab (in some other variants). Testing the port name (Section 3.13) may also work.

  • In the X Window System, you can test the window size (Section 3.16) and make various settings based on that. Naming windows (Section 3.17) lets you identify a particular window by reading its environment.

  • You can also handle some of these cases using the venerable but obscure tset (Section 5.3) program to select and initialize the correct terminal type. Another program that sets the terminal type is qterm (Section 5.4).

Because your terminal type doesn't change after you've logged in, many of these tests probably belong in your .profile or .login file. Those setup files are read when you first log in to a tty. Other tests, especially ones that involve windows, will probably fit better in a per-shell setup file such as .bashrc or .cshrc. Section 3.3 can help you choose.

--JP and SJC

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