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/dev/null 2>&1 Versus /dev/null 2>1

 
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# 1  
Old 03-07-2011
/dev/null 2>&1 Versus /dev/null 2>1
How are these two different? They both prevent output and error from being displayed. I don't see the use of the "&"
Code:
echo "hello" > /dev/null 2>&1 
 echo "hello" > /dev/null 2>1

# 2  
Old 03-07-2011
The one without the ampersand will write the output of standard error into a file named "1". Probably not what's intended.
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# 3  
Old 03-08-2011
Ah, so the ampersand says that 1 is to be recognized as file descriptor 1.. Usually the ampersand says to run a process separate from the shell, correct? Like: mozilla &
# 4  
Old 03-08-2011
Yes, it's a special syntax for file redirection. &>N to write to a specific file descriptor, or &<N to read from a specific file descriptor, where N is an integer representing a valid file descriptor. Standard input is zero, standard output is 1, standard error is 2, anything else can vary.

To read or write from files, you omit the &.
 
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