On Sat, Mar 23, 2013 at 11:57 AM, Jonathan Callen <[email protected]> wrote:
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> On 03/23/2013 01:44 PM, Alec Warner wrote:
>> On Sat, Mar 23, 2013 at 9:26 AM, Michał Górny <[email protected]>
>> wrote:
>>> + # Close the lock file when we are done
>>> with it. + # Prevents deadlock if we aren't
>>> in a subshell. + eval "exec ${lock_fd}>&-"
>>
>> Not following this bit.
>>
>> The bash manpage says N>&DIGIT- redirects fd DIGIT to fd N. N may
>> be unspecified and defaults to 1.
>>
>> It doesn't say what happens if DIGIT is unspecified. Nor does it
>> say it closes any file descriptors.
>>
>
> The relevant section of bash(1) is reproduced below:
>
> Duplicating File Descriptors
> The redirection operator
>
> [n]<&word
>
> is used to duplicate input file descriptors. If word expands to
> one or more digits, the file descriptor denoted by n is made to
> be a copy of that file descriptor. If the digits in word do not
> specify a file descriptor open for input, a redirection error
> occurs. If word evaluates to -, file descriptor n is closed.
> If n is not specified, the standard input (file descriptor 0) is
> used.
>
> The operator
>
> [n]>&word
>
> is used similarly to duplicate output file descriptors. If n is
> not specified, the standard output (file descriptor 1) is used.
> If the digits in word do not specify a file descriptor open for
> output, a redirection error occurs. As a special case, if n is
> omitted, and word does not expand to one or more digits, the
> standard output and standard error are redirected as described
> previously.
>
> While the outcome of n>&- is not specified directly in the man page,
> it is treated exactly as n<&- is.
Ahh, I was reading:
Moving File Descriptors
The redirection operator
[n]<&digit-
moves the file descriptor digit to file descriptor n, or the
standard input (file descriptor 0) if n is not specified. digit is
closed
after being duplicated to n.
Similarly, the redirection operator
[n]>&digit-
moves the file descriptor digit to file descriptor n, or the
standard output (file descriptor 1) if n is not specified.
I see where i went wrong now ;)
>
> - --
> Jonathan Callen
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