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authorandreas_kupries <akupries@shaw.ca>2010-03-03 18:30:26 (GMT)
committerandreas_kupries <akupries@shaw.ca>2010-03-03 18:30:26 (GMT)
commit4a7184ccc431e5e65151b8bccee62179269d099e (patch)
treea2b9633a7d406519fff79a51bd1cf6001573f116 /doc/refchan.n
parent618503676d9bd1174c263775d6a2aeef4a838ae1 (diff)
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* doc/refchan.n: Followup to ChangeLog entry 2009-10-07
(generic/tclIORChan.c). Fixed the documentation to explain that errno numbers are operating system dependent, and reworked the associated example.
Diffstat (limited to 'doc/refchan.n')
-rw-r--r--doc/refchan.n17
1 files changed, 12 insertions, 5 deletions
diff --git a/doc/refchan.n b/doc/refchan.n
index b3ad232..4edd7ad 100644
--- a/doc/refchan.n
+++ b/doc/refchan.n
@@ -4,7 +4,7 @@
'\" See the file "license.terms" for information on usage and redistribution
'\" of this file, and for a DISCLAIMER OF ALL WARRANTIES.
'\"
-'\" RCS: @(#) $Id: refchan.n,v 1.18 2010/01/14 18:13:12 dkf Exp $
+'\" RCS: @(#) $Id: refchan.n,v 1.19 2010/03/03 18:30:28 andreas_kupries Exp $
.so man.macros
.TH refchan n 8.5 Tcl "Tcl Built-In Commands"
.BS
@@ -132,8 +132,11 @@ error EAGAIN
.PP
For extensibility any error whose value is a negative integer number
will cause the higher layers to set the C-level variable "\fBerrno\fR"
-to the absolute value of this number, signaling a system error. This
-means that both
+to the absolute value of this number, signaling a system error.
+However, note that the exact mapping between these error numbers and
+their meanings is operating system dependent.
+.PP
+For example, while on Linux both
.PP
.CS
return -code error -11
@@ -143,8 +146,12 @@ and
error -11
.CE
.PP
-are equivalent to the examples above, using the more readable string "EAGAIN".
-No other error value has such a mapping to a symbolic string.
+are equivalent to the examples above, using the more readable string "EAGAIN",
+this is not true for BSD, where the equivalent number is -35.
+.PP
+The symbolic string however is the same across systems, and internally
+translated to the correct number. No other error value has such a mapping
+to a symbolic string.
.PP
If the subcommand throws any other error, the command which caused its
invocation (usually \fBgets\fR, or \fBread\fR) will appear to have