Re^3: capturing stderr of a command, invoked via backticks (2>&1)

The "| cat" part is superfluous.

Hmmm, you're right of course. I think I formed the habit from shell-isms like so:
./script 2>&1 > file
In that case, without the |cat STDERR is not redirected to file, but that's probably another of my mis-understandings of the mechanism involved.

-David

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Re^4: capturing stderr of a command, invoked via backticks (order) by tye (Sage) on Sep 08, 2007 at 05:02 UTC
`foo 2>&1 >file` is useful but does something other than WYM (what you mean). Order matters. `2>&1` changes STDERR to go where STDOUT currently is and "redirectives" are processed from left to right. So `foo 2>&1 >file \| bar` sends `foo`'s STDOUT to `file` and `foo`'s STDERR to `bar`'s STDIN. What you want is `foo >file 2>&1` which sends both STDOUT and STDERR to `file` (you have to dup STDERR to match STDOUT after you've redirected STDOUT to the file). - tye	[reply] [d/l] [select]

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Re^4: capturing stderr of a command, invoked via backticks (order)
by tye (Sage) on Sep 08, 2007 at 05:02 UTC

foo 2>&1 >file is useful but does something other than WYM (what you mean). Order matters. 2>&1 changes STDERR to go where STDOUT currently is and "redirectives" are processed from left to right. So foo 2>&1 >file | bar sends foo's STDOUT to file and foo's STDERR to bar's STDIN. What you want is foo >file 2>&1 which sends both STDOUT and STDERR to file (you have to dup STDERR to match STDOUT after you've redirected STDOUT to the file).

- tye

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