"What can I do so the characters can't be seen when a user types a password?" is a frequent question. [Tk] applications have a complete and simple answer: use [entry]'s -show option. For a usage example, see [A little login dialog]. A [pure-Tcl] solution is slightly subtler. In a Unix context, the formula is exec stty -echo / echo [[elaborate, including [signal] hygiene ...--which [Expect] handles by itself]] "stty -echo ..." is an error-prone subject. [Don Libes] and [marsd] describe, for example, a long-standing problem that continues to plague Linux 2.4.12 [http://groups.google.com/groups?hl=en&lr=&frame=left&th=5433ad0c03fdc370]. The [Unix Terminal Extension] provides the ability to disable echoing, as well as the ability to read one character at a time from stdin. See [terminal:password:get] for an example. If you don't mind using the Tcl Windows API extension (which only works on Win NT platforms, not Win 98!), the following should do the trick package require twapi set console_handle [twapi::GetStdHandle -10] set oldmode [twapi::GetConsoleMode $console_handle] set newmode [expr {$oldmode & ~4}] ;# Turn off the echo bit twapi::SetConsoleMode $console_handle $newmode gets stdin password ;#...or do whatever... twapi::SetConsoleMode $console_handle $oldmode ;# Restore echo mode The TWAPI extension is available from http://twapi.sf.net