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Help with I/O >&-

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Top Forums Shell Programming and Scripting Help with I/O >&-
# 1  
Old 07-29-2008
Help with I/O >&-
Hi,

I am stuck with the following problem. I run it in unix and it seems the output is indeed sent to STDOUT. Can anyone explain to me the logic behind it?

#!/bin/ksh
exec 4>&1
exec 2>&4
exec 1>&2
exec 4>&-

echo Hello
echo More text

Thanks!
# 2  
Old 07-29-2008
Code:
&1 = stdout
&2 = stderr
&- = close std*

# 3  
Old 07-29-2008
Code:
#!/bin/ksh
exec 4>&1  # copies stdout file descriptor to new descriptor 4
exec 2>&4  # copies descriptor 4 to descriptor 2 (stderr)
exec 1>&2  # copies descriptor 2 to descriptor 1 (stdout)
exec 4>&-  # closes descriptor 4

In short, it seems pretty pointless to me, the same result could be achieved by one line, exec 2>&1 (i.e. both stdout and stderr go to the original destination of stdout).
# 4  
Old 07-30-2008
Thank you both! The explaination is very helpful.

Doris
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