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 use a file-deleting program 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's going to 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 in 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 ( 45.20 ) ) directly to read your answer,
yes
won't work. Try expect ( 9.26 ) instead.
yes
|
yes knows how to say more than just y or n . Article 42.7 shows how to test a terminal with yes . |
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