14.5. Answer "Yes" or "No" Forever with yes
Some commands -- like rm -i, find -ok, and so on -- ask users to answer a "do it or not?" question from the keyboard. For example, you might have a file-deleting program or alias named del that asks before deleting each file:
% del * Remove file1? y Remove file2? y ...
If you answer y, then the file will be deleted.
What if you want to run a command that will ask you 200 questions and you want to answer y to all of them, but you don't want to type all those y s from the keyboard? Pipe the output of yes to the command; it will answer y for you:
% yes | del * Remove file1? Remove file2? ...
If you want to answer n to all the questions, you can do:
% yes n | del *
NOTE: Not all Unix commands read their standard input for answers to prompts. If a command opens your terminal (/dev/tty (Section 36.15)) directly to read your answer, yes won't work. Try expect (Section 28.18) instead.
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