Issue #11638 has been reported by Aleksandar Kostadinov.

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Bug #11638: [doc] misleading IO.write offset description
https://bugs.ruby-lang.org/issues/11638

* Author: Aleksandar Kostadinov
* Status: Open
* Priority: Normal
* Assignee: 
* ruby -v: 
* Backport: 2.0.0: UNKNOWN, 2.1: UNKNOWN, 2.2: UNKNOWN
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"If offset is not given, the file is truncated. Otherwise, it is not truncated."

The above is NOT true when 'a' mode is used. I'd suggest to clarify in documentation that offset is usually 0 if not specified but in 'a' mode it is at end of file or something along these lines.

http://ruby-doc.org/core-2.2.0/IO.html#method-c-write



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