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Message-ID: <54FA731B.8050800@pobox.com>
Date: Fri, 06 Mar 2015 22:40:11 -0500
From: Andrew Janke <janke@pobox.com>
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Subject: FAQ title bar answer using chpwd()
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Hi, ZSH workers,

I have a question about an answer in the ZSH FAQ. Is this the right list 
to ask about it?

http://zsh.sourceforge.net/FAQ/zshfaq03.html#l23

Answer 3.6 suggests using chpwd() to emit terminal control sequences to 
update the title bar for Apple's Terminal.app. This probably isn't the 
right place to do it, because cd's can happen inside functions, 
pipelines, and so on whose output is going to be captured for use 
elsewhere. The terminal control sequences will contaminate the captured 
output instead of going to the terminal.

There's at least one place in the wild where this causes an issue, with 
Android development scripts: 
https://github.com/robbyrussell/oh-my-zsh/issues/3524

The prompt or other known user-interaction output points are probably 
the only safe place to emit terminal control sequences like this. So 
precmd() is probably a better choice than chpwd() for this. It seems 
like chpwd() should probably not be used to do anything that emits to 
stdout, in case it's being captured.

Should the FAQ answer be updated to reflect this?

Cheers,
Andrew