yes (Unix)
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yes is a Unix command, which outputs an affirmative response, or a user-defined string of text continuously until killed.
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[edit] Description
By itself, the yes command outputs 'y' or whatever is specified as an argument, followed by a newline, until stopped by the user or otherwise killed; when piped into a command, it will continue until the pipe breaks (i.e., the program completes its execution).
It can also be used to test how well a system handles high loads, as using yes results in 100% processor usage, for systems with a single processor (for a multiprocessor system, a process must be run for each processor). This, for example, can be useful for investigating whether a system's cooling system will be effective when the processor is running at 100%.
[edit] Uses
yes can be used to send an affirmative (or negative; e.g. yes n) response to any command that would otherwise request one, and thereby causing the command to run non-interactively.
This usage may be obsolete today, as most commands that would request response from the user have either a 'force' option (e.g., rm -f) or an 'assume-yes' option (e.g., apt-get -y in Debian).
As an example, the following:
rm -f *.txt
is equivalent to
yes | rm *.txt
Recently, the yes command has received publicity for being a means to test whether or not a user's MacBook is affected by the Intermittent Shutdown Syndrome. By running the yes command twice via Terminal.app under Mac OS X, users were able to max out their computer's CPU, and thus see if the failure was heat related.[1]
[edit] References
- ^ Testing your MacBook for Random Shut Downs. the apple files (2006-08-02). Archived from the original on 2007-02-10. Retrieved on 2008-01-16.
[edit] External links
- Manpage for yes (GNU version)
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