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Please explain this command?

 
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Top Forums UNIX for Dummies Questions & Answers Please explain this command?
# 1  
Old 01-03-2013
Please explain this command?
Hi,

I saw this. But I don't know why we need this?

Code:
 
ls mydir > foo.txt    ##   I know what this will do, it will take the results and write to the file called foo.txt
 
ls mydir > foo.txt 2>&1  ##   Don't know why we need 2>&1

Thanks.
# 2  
Old 01-03-2013
In case the ls command output some error message, it will go in foo.txt too with the "2>&1" redirection.
# 3  
Old 01-03-2013
There are three standard POSIX file descriptors:-
Code:
0	Standard input (stdin)
1	Standard output (stdout)
2	Standard error (stderr)

So 2>&1 means redirect stderr to stdout.
 
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