This [Unix]-ish command is used to communicate information from a script
level program to a terminal device. It allows one to read and modify the
various device attributes.


Tcl developers often make use of it on [Linux] or other Unix systems when
they want to collect data from user input without requiring the user to
press Return first.

It's also useful for prompting for passwords:

======
proc getpassword {{prompt "Password: "}} {
    puts -nonewline $prompt
    flush stdout
    # disable echoing
    exec stty -echo
    catch { gets stdin } password options
    exec stty echo
    return -options $options $password
}
======

''Gotcha! On some versions of Solaris (at least) you need to pass the descriptor that you want to modify on `stdin` to the subprocess. On Linux, you don't need to: it defaults to the terminal that is the controlling TTY. Because of this difference, you are recommended to invoke `stty` like this:''
======
exec stty {*}$whateverArguments <@stdin
======
======
# Alternatively...
exec stty {*}$whateverArguments </dev/tty
======

----
The [Expect] extension includes an '''stty''' command that takes much the same sort of parameters as the unix utility command.

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**See also**
   * [Expect]
   * [Echo-free password entry]
   * [Reading a single character from the keyboard using Tcl]
<<categories>> Command | Expect | Device Control | Unix