bug#21128: Is this a BUG? Please Help Me !

[Pádraig Brady]

tag 21128 notabug
close 21128
stop

On 24/07/15 09:20, liuquan wrote:
> Dear, engineer! 
> 
> I'm writing this E-mail to you since I think I've found something wrong in 
> Ubuntu!
> 
> My Operating System here is Ubuntu Kylin 14.04.
> 
> I find a question about command 'paste' in command line.
> 
> Support there is a file called "test.txt", and its content is the next 2 
> lines:
> 
> ab
> 
> cd
> 
> If I run the command "paste test.txt", the content of this file will be print 
> at STDOUT. However, when I ran the command "paste test.txt > test.txt" I 
> found that the file "test.txt" became an empty file. Here comes the question, 
> what's going on? Can you help me?

The shell truncated the file before paste could read it.
You need to write to a temp file first. For details see:
http://www.pixelbeat.org/docs/unix_file_replacement.html

thanks,
Pádraig.