Configuration Information [Automatically generated, do not change]:
Machine: i486
OS: linux-gnu
Compiler: gcc
Compilation CFLAGS: -DPROGRAM='bash' -DCONF_HOSTTYPE='i486'
-DCONF_OSTYPE='linux-gnu' -DCONF_MACHTYPE='i486-pc-linux-gnu'
-DCONF_VENDOR='pc' -DLOCALEDIR='/usr/share/locale' -DPACKAGE='bash' -DSHELL
-DHAVE_CONFIG_H -I. -I../bash -I../bash/include -I../bash/lib -g -O2 -Wall
uname output: Linux QGZ 3.0.0-1-686-pae #1 SMP Sat Aug 27 16:41:03 UTC 2011
i686 GNU/Linux
Machine Type: i486-pc-linux-gnu
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.
Repeat-By:
$ cat abc.sh
#!/bin/bash
tput lines
echo $(tput lines)
If execute the script with the content above, it is all right like :
$ ./abc.sh
50
50
But if execute the script like this :
$ ./abc.sh 2>/dev/null
We will get :
50
24
I don't know why it is. What is amazing is the number 24.
The number would never change no matter how I resize the console or
other terminals.
It also happens when a line of command in the script like "tput lines |
cat".
I haven't see the source code of BASH. I'm very sorry for having no
good advice about this.
And also sorry for my poor English. @_@
