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Re: read -t

From: Eduardo A . Bustamante López
Subject: Re: read -t
Date: Sun, 4 Jan 2015 13:21:41 -0800
User-agent: Mutt/1.5.23 (2014-03-12)

I think the issue here is the inconsistent behavior of read -t <num> when 
delim != '\n'.

read -t 3 -d <not-\n> will *not* leave the input as typeahead.
read -t 3 -d $'\n'    will leave the input as typeahead.

I tried playing with the 'unbuffered_read' variable in builtins/read.def
(forcing it to be 1 even for delim == '\n'), but it seems that the special
behavior for '\n' is further down the code.

Also, this is how ksh93 and zsh behave:

ksh93 behaves consistently (delim == or != to '\n')
| address@hidden ...local/src/bash % /bin/ksh93 -c "false; read -t 3"
| afafafafafafa%
| address@hidden ...local/src/bash % /bin/ksh93 -c "false; read -d d -t 3"
| afafafafafafa%

zsh ignores -t when a custom -d is in effect, does the same thing as bash when
delim == '\n'
| address@hidden ...local/src/bash % /bin/zsh -c "false; read -t 3"     
| afafafafafafafafa%
| address@hidden ...local/src/bash % afafafafafafafafa<RET>
| zsh: command not found: afafafafafafafafa
| address@hidden ...local/src/bash % /bin/zsh -c "false; read -d d -t 3" 
| afafafafafafafa
| d%<had to type d, the timeout was not working>

bash leaves the input in some buffer when delim == '\n' and the timeout is
reached. It consumes the input when delim != '\n'.
| address@hidden ...local/src/bash % /bin/bash -c "false; read -t 3" 
| afafafafafaf%
| address@hidden ...local/src/bash % afafafafafaf<RET>
| zsh: command not found: afafafafafaf
| address@hidden ...local/src/bash % /bin/bash -c "false; read -d d -t 3"
| afafafafafafafaf%
| address@hidden ...local/src/bash %

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