perldiag.1

视频监控网络部分的协议ddns,的模块的实现代码,请大家大胆指正.

(F) Subroutines meant to be used in lvalue context should be declared as
such, see \*(L"Lvalue subroutines\*(R" in perlsub.
.IP "Can't msgrcv to read-only var" 4
.IX Item "Can't msgrcv to read-only var"
(F) The target of a msgrcv must be modifiable to be used as a receive
buffer.
.ie n .IP "Can't ""next"" outside a loop block" 4
.el .IP "Can't ``next'' outside a loop block" 4
.IX Item "Can't next outside a loop block"
(F) A \*(L"next\*(R" statement was executed to reiterate the current block, but
there isn't a current block.  Note that an \*(L"if\*(R" or \*(L"else\*(R" block doesn't
count as a \*(L"loopish\*(R" block, as doesn't a block given to \fIsort()\fR, \fImap()\fR or
\&\fIgrep()\fR.  You can usually double the curlies to get the same effect
though, because the inner curlies will be considered a block that loops
once.  See \*(L"next\*(R" in perlfunc.
.ie n .IP "Can't open %s:\fR \f(CW%s" 4
.el .IP "Can't open \f(CW%s:\fR \f(CW%s\fR" 4
.IX Item "Can't open %s: %s"
(S inplace) The implicit opening of a file through use of the \f(CW\*(C`<>\*(C'\fR
filehandle, either implicitly under the \f(CW\*(C`\-n\*(C'\fR or \f(CW\*(C`\-p\*(C'\fR command-line
switches, or explicitly, failed for the indicated reason.  Usually this
is because you don't have read permission for a file which you named on
the command line.
.IP "Can't open a reference" 4
.IX Item "Can't open a reference"
(W io) You tried to open a scalar reference for reading or writing,
using the 3\-arg \fIopen()\fR syntax :
.Sp
.Vb 1
\&    open FH, \*(Aq>\*(Aq, $ref;
.Ve
.Sp
but your version of perl is compiled without perlio, and this form of
open is not supported.
.IP "Can't open bidirectional pipe" 4
.IX Item "Can't open bidirectional pipe"
(W pipe) You tried to say \f(CW\*(C`open(CMD, "|cmd|")\*(C'\fR, which is not supported.
You can try any of several modules in the Perl library to do this, such
as IPC::Open2.  Alternately, direct the pipe's output to a file using
\&\*(L">\*(R", and then read it in under a different file handle.
.ie n .IP "Can't open error file %s as stderr" 4
.el .IP "Can't open error file \f(CW%s\fR as stderr" 4
.IX Item "Can't open error file %s as stderr"
(F) An error peculiar to \s-1VMS\s0.  Perl does its own command line
redirection, and couldn't open the file specified after '2>' or '2>>' on
the command line for writing.
.ie n .IP "Can't open input file %s as stdin" 4
.el .IP "Can't open input file \f(CW%s\fR as stdin" 4
.IX Item "Can't open input file %s as stdin"
(F) An error peculiar to \s-1VMS\s0.  Perl does its own command line
redirection, and couldn't open the file specified after '<' on the
command line for reading.
.ie n .IP "Can't open output file %s as stdout" 4
.el .IP "Can't open output file \f(CW%s\fR as stdout" 4
.IX Item "Can't open output file %s as stdout"
(F) An error peculiar to \s-1VMS\s0.  Perl does its own command line
redirection, and couldn't open the file specified after '>' or '>>' on
the command line for writing.
.ie n .IP "Can't open output pipe (name: %s)" 4
.el .IP "Can't open output pipe (name: \f(CW%s\fR)" 4
.IX Item "Can't open output pipe (name: %s)"
(P) An error peculiar to \s-1VMS\s0.  Perl does its own command line
redirection, and couldn't open the pipe into which to send data destined
for stdout.
.IP "Can't open perl script%s" 4
.IX Item "Can't open perl script%s"
(F) The script you specified can't be opened for the indicated reason.
.Sp
If you're debugging a script that uses #!, and normally relies on the
shell's \f(CW$PATH\fR search, the \-S option causes perl to do that search, so
you don't have to type the path or \f(CW\*(C`\`which $scriptname\`\*(C'\fR.
.IP "Can't read \s-1CRTL\s0 environ" 4
.IX Item "Can't read CRTL environ"
(S) A warning peculiar to \s-1VMS\s0.  Perl tried to read an element of \f(CW%ENV\fR
from the \s-1CRTL\s0's internal environment array and discovered the array was
missing.  You need to figure out where your \s-1CRTL\s0 misplaced its environ
or define \fI\s-1PERL_ENV_TABLES\s0\fR (see perlvms) so that environ is not
searched.
.ie n .IP "Can't ""redo"" outside a loop block" 4
.el .IP "Can't ``redo'' outside a loop block" 4
.IX Item "Can't redo outside a loop block"
(F) A \*(L"redo\*(R" statement was executed to restart the current block, but
there isn't a current block.  Note that an \*(L"if\*(R" or \*(L"else\*(R" block doesn't
count as a \*(L"loopish\*(R" block, as doesn't a block given to \fIsort()\fR, \fImap()\fR
or \fIgrep()\fR.  You can usually double the curlies to get the same effect
though, because the inner curlies will be considered a block that
loops once.  See \*(L"redo\*(R" in perlfunc.
.ie n .IP "Can't remove %s:\fR \f(CW%s, skipping file" 4
.el .IP "Can't remove \f(CW%s:\fR \f(CW%s\fR, skipping file" 4
.IX Item "Can't remove %s: %s, skipping file"
(S inplace) You requested an inplace edit without creating a backup
file.  Perl was unable to remove the original file to replace it with
the modified file.  The file was left unmodified.
.ie n .IP "Can't rename %s\fR to \f(CW%s:\fR \f(CW%s, skipping file" 4
.el .IP "Can't rename \f(CW%s\fR to \f(CW%s:\fR \f(CW%s\fR, skipping file" 4
.IX Item "Can't rename %s to %s: %s, skipping file"
(S inplace) The rename done by the \fB\-i\fR switch failed for some reason,
probably because you don't have write permission to the directory.
.ie n .IP "Can't reopen input pipe (name: %s) in binary mode" 4
.el .IP "Can't reopen input pipe (name: \f(CW%s\fR) in binary mode" 4
.IX Item "Can't reopen input pipe (name: %s) in binary mode"
(P) An error peculiar to \s-1VMS\s0.  Perl thought stdin was a pipe, and tried
to reopen it to accept binary data.  Alas, it failed.
.IP "Can't resolve method `%s' overloading `%s' in package `%s'" 4
.IX Item "Can't resolve method `%s' overloading `%s' in package `%s'"
(F|P) Error resolving overloading specified by a method name (as opposed
to a subroutine reference): no such method callable via the package. If
method name is \f(CW\*(C`???\*(C'\fR, this is an internal error.
.IP "Can't reswap uid and euid" 4
.IX Item "Can't reswap uid and euid"
(P) The \fIsetreuid()\fR call failed for some reason in the setuid emulator of
suidperl.
.ie n .IP "Can't return %s from lvalue subroutine" 4
.el .IP "Can't return \f(CW%s\fR from lvalue subroutine" 4
.IX Item "Can't return %s from lvalue subroutine"
(F) Perl detected an attempt to return illegal lvalues (such as
temporary or readonly values) from a subroutine used as an lvalue.  This
is not allowed.
.IP "Can't return outside a subroutine" 4
.IX Item "Can't return outside a subroutine"
(F) The return statement was executed in mainline code, that is, where
there was no subroutine call to return out of.  See perlsub.
.ie n .IP "Can't return %s to lvalue scalar context" 4
.el .IP "Can't return \f(CW%s\fR to lvalue scalar context" 4
.IX Item "Can't return %s to lvalue scalar context"
(F) You tried to return a complete array or hash from an lvalue subroutine,
but you called the subroutine in a way that made Perl think you meant
to return only one value. You probably meant to write parentheses around
the call to the subroutine, which tell Perl that the call should be in
list context.
.ie n .IP "Can't stat script ""%s""" 4
.el .IP "Can't stat script ``%s''" 4
.IX Item "Can't stat script %s"
(P) For some reason you can't \fIfstat()\fR the script even though you have it
open already.  Bizarre.
.IP "Can't swap uid and euid" 4
.IX Item "Can't swap uid and euid"
(P) The \fIsetreuid()\fR call failed for some reason in the setuid emulator of
suidperl.
.ie n .IP "Can't take log of %g" 4
.el .IP "Can't take log of \f(CW%g\fR" 4
.IX Item "Can't take log of %g"
(F) For ordinary real numbers, you can't take the logarithm of a
negative number or zero. There's a Math::Complex package that comes
standard with Perl, though, if you really want to do that for the
negative numbers.
.ie n .IP "Can't take sqrt of %g" 4
.el .IP "Can't take sqrt of \f(CW%g\fR" 4
.IX Item "Can't take sqrt of %g"
(F) For ordinary real numbers, you can't take the square root of a
negative number.  There's a Math::Complex package that comes standard
with Perl, though, if you really want to do that.
.IP "Can't undef active subroutine" 4
.IX Item "Can't undef active subroutine"
(F) You can't undefine a routine that's currently running.  You can,
however, redefine it while it's running, and you can even undef the
redefined subroutine while the old routine is running.  Go figure.
.IP "Can't unshift" 4
.IX Item "Can't unshift"
(F) You tried to unshift an \*(L"unreal\*(R" array that can't be unshifted, such
as the main Perl stack.
.ie n .IP "Can't upgrade %s\fR (%d) to \f(CW%d" 4
.el .IP "Can't upgrade \f(CW%s\fR (%d) to \f(CW%d\fR" 4
.IX Item "Can't upgrade %s (%d) to %d"
(P) The internal sv_upgrade routine adds \*(L"members\*(R" to an \s-1SV\s0, making it
into a more specialized kind of \s-1SV\s0.  The top several \s-1SV\s0 types are so
specialized, however, that they cannot be interconverted.  This message
indicates that such a conversion was attempted.
.IP "Can't use anonymous symbol table for method lookup" 4
.IX Item "Can't use anonymous symbol table for method lookup"
(F) The internal routine that does method lookup was handed a symbol
table that doesn't have a name.  Symbol tables can become anonymous
for example by undefining stashes: \f(CW\*(C`undef %Some::Package::\*(C'\fR.
.ie n .IP "Can't use an undefined value as %s reference" 4
.el .IP "Can't use an undefined value as \f(CW%s\fR reference" 4
.IX Item "Can't use an undefined value as %s reference"
(F) A value used as either a hard reference or a symbolic reference must
be a defined value.  This helps to delurk some insidious errors.
.ie n .IP "Can't use bareword (""%s"") as %s ref while ""strict refs"" in use" 4
.el .IP "Can't use bareword (``%s'') as \f(CW%s\fR ref while ``strict refs'' in use" 4
.IX Item "Can't use bareword (%s) as %s ref while strict refs in use"
(F) Only hard references are allowed by \*(L"strict refs\*(R".  Symbolic
references are disallowed.  See perlref.
.IP "Can't use %! because Errno.pm is not available" 4
.IX Item "Can't use %! because Errno.pm is not available"
(F) The first time the %! hash is used, perl automatically loads the
Errno.pm module. The Errno module is expected to tie the %! hash to
provide symbolic names for \f(CW$!\fR errno values.
.ie n .IP "Can't use both '<' and '>' after type '%c' in %s" 4
.el .IP "Can't use both '<' and '>' after type '%c' in \f(CW%s\fR" 4
.IX Item "Can't use both '<' and '>' after type '%c' in %s"
(F) A type cannot be forced to have both big-endian and little-endian
byte-order at the same time, so this combination of modifiers is not
allowed.  See \*(L"pack\*(R" in perlfunc.
.ie n .IP "Can't use %s for loop variable" 4
.el .IP "Can't use \f(CW%s\fR for loop variable" 4
.IX Item "Can't use %s for loop variable"
(F) Only a simple scalar variable may be used as a loop variable on a
foreach.
.ie n .IP "Can't use global %s in ""%s""" 4
.el .IP "Can't use global \f(CW%s\fR in ``%s''" 4
.IX Item "Can't use global %s in %s"
(F) You tried to declare a magical variable as a lexical variable.  This
is not allowed, because the magic can be tied to only one location
(namely the global variable) and it would be incredibly confusing to
have variables in your program that looked like magical variables but
weren't.
.ie n .IP "Can't use '%c' in a group with different byte-order in %s" 4
.el .IP "Can't use '%c' in a group with different byte-order in \f(CW%s\fR" 4
.IX Item "Can't use '%c' in a group with different byte-order in %s"
(F) You attempted to force a different byte-order on a type
that is already inside a group with a byte-order modifier.
For example you cannot force little-endianness on a type that
is inside a big-endian group.
.ie n .IP "Can't use ""my %s"" in sort comparison" 4
.el .IP "Can't use ``my \f(CW%s\fR'' in sort comparison" 4
.IX Item "Can't use my %s in sort comparison"
(F) The global variables \f(CW$a\fR and \f(CW$b\fR are reserved for sort comparisons.
You mentioned \f(CW$a\fR or \f(CW$b\fR in the same line as the <=> or cmp operator,
and the variable had earlier been declared as a lexical variable.
Either qualify the sort variable with the package name, or rename the
lexical variable.
.ie n .IP "Can't use %s\fR ref as \f(CW%s ref" 4
.el .IP "Can't use \f(CW%s\fR ref as \f(CW%s\fR ref" 4
.IX Item "Can't use %s ref as %s ref"
(F) You've mixed up your reference types.  You have to dereference a
reference of the type needed.  You can use the \fIref()\fR function to
test the type of the reference, if need be.
.ie n .IP "Can't use string (""%s"") as %s ref while ""strict refs"" in use" 4
.el .IP "Can't use string (``%s'') as \f(CW%s\fR ref while ``strict refs'' in use" 4
.IX Item "Can't use string (%s) as %s ref while strict refs in use"
(F) Only hard references are allowed by \*(L"strict refs\*(R".  Symbolic
references are disallowed.  See perlref.
.ie n .IP "Can't use subscript on %s" 4
.el .IP "Can't use subscript on \f(CW%s\fR" 4
.IX Item "Can't use subscript on %s"
(F) The compiler tried to interpret a bracketed expression as a
subscript.  But to the left of the brackets was an expression that
didn't look like a hash or array reference, or anything else subscriptable.
.IP "Can't use \e%c to mean $%c in expression" 4
.IX Item "Can't use %c to mean $%c in expression"
(W syntax) In an ordinary expression, backslash is a unary operator that
creates a reference to its argument.  The use of backslash to indicate a
backreference to a matched substring is valid only as part of a regular
expression pattern.  Trying to do this in ordinary Perl code produces a
value that prints out looking like \s-1\fISCALAR\s0\fR\|(0xdecaf).  Use the \f(CW$1\fR form
instead.
.ie n .IP "Can't use ""when"" outside a topicalizer" 4
.el .IP "Can't use ``when'' outside a topicalizer" 4
.IX Item "Can't use when outside a topicalizer"
(F) You have used a \fIwhen()\fR block that is neither inside a \f(CW\*(C`foreach\*(C'\fR
loop nor a \f(CW\*(C`given\*(C'\fR block. (Note that this error is issued on exit
from the \f(CW\*(C`when\*(C'\fR block, so you won't get the error if the match fails,
or if you use an explicit \f(CW\*(C`continue\*(C'\fR.)
.IP "Can't weaken a nonreference" 4