Version: GNU bash, version 4.2.47(1)-release (x86_64-redhat-linux-gnu)
Problem: Manual page does not describe the redirection form "n>&-".
The manual page section "Duplicating File Descriptors" is as follows:
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 evalu‐
ates 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 re‐
direction 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.
However, the last paragraph does not describe the form "n>&-" (which
does close descriptor n). Perhaps that is implied by "similarly", but
it would be better to spell it out:
is used similarly to duplicate output 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
output, a redirection error occurs. If word expands to -,
file descriptor n is closed. If n is not specified, the
standard output (file descriptor 1) is used. 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.
In addition, the word "evaluates" in the first paragraph should be
"expands".
The change to file bash.1 is:
--- /home/worley/temp/b0 2014-05-29 14:56:17.631508858 -0400
+++ /home/worley/temp/b1 2014-05-29 14:59:00.596458326 -0400
@@ -17,7 +17,7 @@
do not specify a file descriptor open for input, a redirection error occurs.
If
.I word
-evaluates to
+expands to
.BR \- ,
file descriptor
.I n
@@ -31,12 +31,24 @@
[\fIn\fP]\fB>&\fP\fIword\fP
.RE
.PP
-is used similarly to duplicate output file descriptors. If
+is used similarly to duplicate output file descriptors.
+If
+.I word
+expands to one or more digits, the file descriptor denoted by
.I n
-is not specified, the standard output (file descriptor 1) is used.
+is made to be a copy of that file descriptor.
If the digits in
.I word
do not specify a file descriptor open for output, a redirection error occurs.
+If
+.I word
+expands to
+.BR \- ,
+file descriptor
+.I n
+is closed. If
+.I n
+is not specified, the standard output (file descriptor 1) is used.
As a special case, if \fIn\fP is omitted, and \fIword\fP does not
expand to one or more digits, the standard output and standard
error are redirected as described previously.
Dale
