A common annoyance among Emacs users is the problem that occurs in some situations involving terminals (as opposed to PCs or workstations). Some operating systems and data communications devices (terminals, modems, networks, etc.) use the characters CTRL-s and CTRL-q to act as "stop" and "go" signs for terminal input and output, to prevent buffer overflow.
Many more modern systems use other means of flow control, such as extra hardware, but others still use the CTRL-s/CTRL-q convention. This is especially likely in situations where there are multiple data communications devices between you and the actual computer (for example, a terminal talking to a modem, talking to another modem, talking to a terminal server, talking to a local area network, talking to a computer, remotely logged in to another computer...).
In general, the more pieces of hardware between you and the computer, the more likely that CTRL-s and CTRL-q are used as flow control characters; this means that those two characters are not accessible to Emacs.
To find out whether the problem affects you, simply invoke Emacs
and type CTRL-s. If you see the
An easy way to get around this problem is to type
To set this up so it works all the time, add this line to your .emacs file:
Remember that you should exit and restart Emacs to make changes to your .emacs file take effect.