On Fri, Nov 25, 2011 at 10:27:07PM -0500, Chet Ramey wrote:
>
>On 11/24/11 11:48 AM, QGZ wrote:
>
>> Bash Version: 4.1
>> Patch Level: 5
>> Release Status: release
>>
>>
>>
>> Description:
>> When I use "tput lines" to get the lines of console, it works, and
>> also works in a script.
>> And if execute the command in a script with the command
>> substitution, it works well too.
>> But if execute the script with the redirection "2>/dev/null", it
>> won't work well.
>> I'm not sure whether it is a bug or just my lack of some required
>> knowledge.
>> Please see one example below.
>
>This doesn't have anything to do with bash. tput probably uses the
>standard output as a handle to the terminal. When run in a command
>substitution, stdout is a pipe. You might take a look at what tput
>does using a system call tracer like truss or strace.
>
>Chet
>
Thanks for your suggestion!
I have got what happened there with the help which is similar to yours from
Jonathan Nieder <jrnie...@gmail.com>:
"Tput checks if the standard output (file descriptor 1) and standard error
(file descriptor 2) streams are terminals and communicates with the terminal
using whichever one is a tty."
It's working now when executing in a command substitution in a script like this:
echo $(tput lines 2>/dev/tty)
Thank you!
--QGZ
