PERLDIAG(1)

NAME
perldiag - various Perl diagnostics

DESCRIPTION
These messages are classified as follows (listed in increasing order of desperation):

    (W) A warning (optional).
    (D) A deprecation (optional).
    (S) A severe warning (mandatory).
    (F) A fatal error (trappable).
    (P) An internal error you should never see (trappable).
    (X) A very fatal error (non-trappable).
Optional warnings are enabled by using the -w switch. Warnings may be captured by setting $^Q to a reference to a routine that will be called on each warning instead of printing it. See the perlvar manpage. Trappable errors may be trapped using the eval operator. See the eval entry in the perlfunc manpage.

Some of these messages are generic. Spots that vary are denoted with a %s, just as in a printf format. Note that some message start with a %s! The symbols "%-?@ sort before the letters, while [ and \ sort after. (F) Lexically scoped variables aren't in a package, so it doesn't make sense to try to declare one with a package qualifier on the front. Use local() if you want to localize a package variable. (F) The "no" keyword is recognized and executed at compile time, and returns no useful value. See the perlmod manpage. (F) The "use" keyword is recognized and executed at compile time, and returns no useful value. See the perlmod manpage. (F) You can't pack a string by supplying a checksum, since the checksumming process loses information, and you can't go the other way. See the unpack entry in the perlfunc manpage. (W) You've run afoul of the rule that says that any list operator followed by parentheses turns into a function, with all the list operators arguments found inside the parens. See the section on Terms and List Operators (Leftward) in the perlop manpage. (F) The argument to delete() or exists() must be a hash element, such as

    $foo{$bar}
    $ref->[12]->{"susie"}
(F) A required (or used) file must return a true value to indicate that it compiled correctly and ran its initialization code correctly. It's traditional to end such a file with a "1;", though any true value would do. See the require entry in the perlfunc manpage. (S) The Perl lexer knows whether to expect a term or an operator. If it sees what it knows to be a term when it was expecting to see an operator, it gives you this warning. Usually it indicates that an operator or delimiter was omitted, such as a semicolon. (F) The final summary message when a perl -c fails. (F) The parser has given up trying to parse the program after 10 errors. Further error messages would likely be uninformative. (W) The pattern you've specified would be an infinite loop if the regular expression engine didn't specifically check for that. See the perlre manpage. (S) The symbol in question was declared but somehow went out of scope before it could possibly have been used. (F) The final summary message when a perl -c succeeds. (F) The script would have to be opened by the C preprocessor by name, which provides a race condition that breaks security. (F) Perl can't peek at the stdio buffer of filehandles when it doesn't know about your kind of stdio. You'll have to use a filename instead. (F) You started a regular expression with a quantifier. Backslash it if you meant it literally. See the perlre manpage. (F) You had a pack template that specified an absolution position outside the string being unpacked. See the pack entry in the perlfunc manpage. (W) You tried to do an accept on a closed socket. Did you forget to check the return value of your socket() call? See the accept entry in the perlfunc manpage. (F) You can't allocate more than 64K on an MSDOS machine. (F) msgsnd() requires a string at least as long as sizeof(long). (W)(S) You said something that may not be interpreted the way you thought. Normally it's pretty easy to disambiguate it by supplying a missing quote, operator, paren pair or declaration. (F) The setuid emulator requires that the arguments Perl was invoked with match the arguments specified on the #! line. (W) The indicated string was fed as an argument to an operator that expected a numeric value instead. If you're fortunate the message will identify which operator was so unfortunate. (D) Really old Perl let you omit the @ on array names in some spots. This is now heavily deprecated. (P) The malloc package that comes with Perl had an internal failure. (P) A general assertion failed. The file in question must be examined. (F) If you assign to a conditional operator, the 2nd and 3rd arguments must either both be scalars or both be lists. Otherwise Perl won't know which context to supply to the right side. (P) All SV objects are supposed to be allocated from arenas that will be garbage collected on exit. An SV was discovered to be outside any of those arenas. (W) Mortalized values are supposed to be freed by the free_tmps() routine. This indicates that something else is freeing the SV before the free_tmps() routine gets a chance, which means that the free_tmps() routine will be freeing an unreferenced scalar when it does try to free it. (P) The reference counts got screwed up on symbol aliases. (W) Perl went to decrement the reference count of a scalar to see if it would go to 0, and discovered that it had already gone to 0 earlier, and should have been freed, and in fact, probably was freed. This could indicate that SvREFCNT_dec() was called too many times, or that SvREFCNT_inc() was called too few times, or that the SV was mortalized when it shouldn't have been, or that memory has been corrupted. (F) You passed a buffer of the wrong size to one of msgctl(), semctl() or shmctl(). In C parlance, the correct sized are, respectively, sizeof(struct msqid_ds *), sizeof(struct semid_ds *) and sizeof(struct shmid_ds *). (P) One of the internal hash routines was passed a null HV pointer. (F) A symbol was passed to something wanting a filehandle, but the symbol has no filehandle associated with it. Perhaps you didn't do an open(), or did it in another package. (S) An internal routine called free() on something that had never been malloc()ed in the first place. (F) You started to name a symbol by using a package prefix, and then didn't finish the symbol. In particular, you can't interpolate outside of quotes, so

    $var = 'myvar';
    $sym = mypack::$var;
is not the same as

    $var = 'myvar';
    $sym = "mypack::$var";
(P) An internal request asked to add an array entry to something that wasn't a symbol table entry. (P) An internal request asked to add a filehandle entry to something that wasn't a symbol table entry. (P) An internal request asked to add a hash entry to something that wasn't a symbol table entry. (F) An untrapped exception was raised while executing a BEGIN subroutine. Compilation stops immediately and the interpreter is exited. (W) You tried to do a bind on a closed socket. Did you forget to check the return value of your socket() call? See the bind entry in the perlfunc manpage. (F) A subroutine invoked from an external package via perl_call_sv() exited by calling exit. (F) A "last" statement was executed to break out of the current block, except that there's this itty bitty problem called there isn't a current block. Note that an "if" or "else" block doesn't count as a "loopish" block. You can usually double the curlies to get the same effect though, since the inner curlies will be considered a block that loops once. See the last entry in the perlfunc manpage. (F) A "next" statement was executed to reiterate the current block, but there isn't a current block. Note that an "if" or "else" block doesn't count as a "loopish" block. You can usually double the curlies to get the same effect though, since the inner curlies will be considered a block that loops once. See the last entry in the perlfunc manpage. (F) A "redo" statement was executed to restart the current block, but there isn't a current block. Note that an "if" or "else" block doesn't count as a "loopish" block. You can usually double the curlies to get the same effect though, since the inner curlies will be considered a block that loops once. See the last entry in the perlfunc manpage. (F) Only hard references may be blessed. This is how Perl "enforces" encapsulation of objects. See the perlobj manpage. (S) A warning intended for while running within the debugger, indicating the line number specified wasn't the location of a statement that could be stopped at. (F) You called a method correctly, and it correctly indicated a package functioning as a class, but that package doesn't have ANYTHING defined in it, let alone methods. See the perlobj manpage. (F) A method call must know what package it's supposed to run in. It ordinarily finds this out from the object reference you supply, but you didn't supply an object reference in this case. A reference isn't an object reference until it has been blessed. See the perlobj manpage. (F) You used the syntax of a method call, but the slot filled by the object reference or package name contains an expression that returns neither an object reference nor a package name. (Perhaps it's null?) Something like this will reproduce the error:

    $BADREF = undef;
    process $BADREF 1,2,3;
    $BADREF->process(1,2,3);
(F) You called perl -x/foo/bar, but /foo/bar is not a directory that you can chdir to, possibly because it doesn't exist. (F) Certain types of SVs, in particular real symbol table entries (type GLOB), can't be forced to stop being what they are. So you can't say things like:

    *foo += 1;
You CAN say

    $foo = *foo;
    $foo += 1;
but then $foo no longer contains a glob. (F) Certain types of SVs, in particular real symbol table entries (type GLOB), can't be forced to stop being what they are. (F) Certain types of SVs, in particular real symbol table entries (type GLOB), can't be forced to stop being what they are. (P) An error peculiar to VMS. The process is suffering from exhausted quotas or other plumbing problems. (F) Only scalar, array and hash variables may be declared as lexical variables. They must have ordinary identifiers as names. (S) The creation of the new file failed for the indicated reason. (F) You're on a system such as MSDOS that gets confused if you try reading from a deleted (but still opened) file. You have to say -i.bak, or some such. (S) There isn't enough room in the filename to make a backup name for the file. (S) You tried to use the -i switch on a special file, such as a file in /dev, or a FIFO. The file was ignored. (P) The setegid() call failed for some reason in the setuid emulator of suidperl. (P) The setuid emulator of suidperl failed for some reason. (F) This typically means that ordinary perl tried to exec suidperl to do setuid emulation, but couldn't exec it. It looks for a name of the form sperl5.000 in the same directory that the perl executable resides under the name perl5.000, typically /usr/local/bin on Unix machines. If the file is there, check the execute permissions. If it isn't, ask your sysadmin why he and/or she removed it. (F) This machine doesn't have either waitpid() or wait4(), so only waitpid() without flags is emulated. (F) Minima must be less than or equal to maxima. If you really want your regexp to match something 0 times, just put {0}. See the perlre manpage. (F) The #! line specifies a switch that doesn't make sense at this point. For example, it'd be kind of silly to put a -x on the #! line. (W) An system(), exec() or piped open call could not execute the named program for the indicated reason. Typical reasons include: the permissions were wrong on the file, the file wasn't found in $ENV{PATH}, the executable in question was compiled for another architecture, or the #! line in a script points to an interpreter that can't be run for similar reasons. (Or maybe your system doesn't support #! at all.) (F) Perl was trying to execute the indicated program for you because that's what the #! line said. If that's not what you wanted, you may need to mention "perl" on the #! line somewhere. (F) You used the -S switch, but the script to execute could not be found in the PATH, or at least not with the correct permissions. (F) You said to goto a label that isn't mentioned anywhere that it's possible for us to go to. See the goto entry in the perlfunc manpage. (F) Perl strings can stretch over multiple lines. This message means that the closing delimiter was omitted. Since bracketed quotes count nesting levels, the following is missing its final parenthesis:

    print q(The character '(' starts a side comment.)
(F) A fatal error occurred while trying to fork while opening a pipeline. (S) A warning peculiar to VMS. This arises because of the difference between access checks under VMS and under the Unix model Perl assumes. Under VMS, access checks are done by filename, rather than by bits in the stat buffer, so that ACLs and other protections can be taken into account. Unfortunately, Perl assumes that the stat buffer contains all the necessary information, and passes it, instead of the filespec, to the access checking routine. It will try to retrieve the filespec using the device name and FID present in the stat buffer, but this works only if you haven't made a subsequent call to the CRTL stat() routine, since the device name is overwritten with each call. If this warning appears, the name lookup failed, and the access checking routine gave up and returned FALSE, just to be conservative. (Note: The access checking routine knows about the Perl stat operator and file tests, so you shouldn't ever see this warning in response to a Perl command; it arises only if some internal code takes stat buffers lightly.) (P) An error peculiar to VMS. After creating a mailbox to act as a pipe, Perl can't retrieve its name for later use. (P) An error peculiar to VMS. Perl asked $GETSYI how big you want your mailbox buffers to be, and didn't get an answer. (F) The deeply magical "goto subroutine" call can only replace one subroutine call for another. It can't manufacture one out of whole cloth. In general you should only be calling it out of an AUTOLOAD routine anyway. See the goto entry in the perlfunc manpage. (F) You used local on a variable name that was previous declared as a lexical variable using "my". This is not allowed. If you want to localize a package variable of the same name, qualify it with the package name. (F) You said to do (or require, or use) a file that couldn't be found in any of the libraries mentioned in @INC. Perhaps you need to set the PERL5LIB environment variable to say where the extra library is, or maybe the script needs to add the library name to @INC. Or maybe you just misspelled the name of the file. See the require entry in the perlfunc manpage. (F) You called a method correctly, and it correctly indicated a package functioning as a class, but that package doesn't define that particular method, nor does any of it's base classes. See the perlobj manpage. (W) The @ISA array contained the name of another package that doesn't seem to exist. (F) The mktemp() routine failed for some reason while trying to process a -e switch. Maybe your /tmp partition is full, or clobbered. (F) You aren't allowed to assign to the item indicated, or otherwise try to change it, such as with an autoincrement. (P) The internal routine that does assignment to a substr() was handed a NULL. (F) The target of a msgrcv must be modifiable in order to be used as a receive buffer. (S) An inplace edit couldn't open the original file for the indicated reason. Usually this is because you don't have read permission for the file. (W) You tried to say open(CMD, "|cmd|"), which is not supported. You can try any of several modules in the Perl library to do this, such as "open2.pl". Alternately, direct the pipe's output to a file using ">", and then read it in under a different file handle. (F) An error peculiar to VMS. Perl does its own command line redirection, and couldn't open the file specified after '2>' or '2>>' on the command line for writing. (F) An error peculiar to VMS. Perl does its own command line redirection, and couldn't open the file specified after '<' on the command line for reading. (F) An error peculiar to VMS. Perl does its own command line redirection, and couldn't open the file specified after '>' or '>>' on the command line for writing. (P) An error peculiar to VMS. Perl does its own command line redirection, and couldn't open the pipe into which to send data destined for stdout. (F) The script you specified can't be opened for the indicated reason. (S) The rename done by the -i switch failed for some reason, probably because you don't have write permission to the directory. (P) An error peculiar to VMS. Perl thought stdin was a pipe, and tried to reopen it to accept binary data. Alas, it failed. (P) The setreuid() call failed for some reason in the setuid emulator of suidperl. (F) The return statement was executed in mainline code, that is, where there was no subroutine call to return out of. See the perlsub manpage. (P) For some reason you can't fstat() the script even though you have it open already. Bizarre. (P) The setreuid() call failed for some reason in the setuid emulator of suidperl. (F) Logarithms are only defined on positive real numbers. (F) For ordinary real numbers, you can't take the square root of a negative number. There's a Complex package available for Perl, though, if you really want to do that. (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. (F) You tried to unshift an "unreal" array that can't be unshifted, such as the main Perl stack. (P) The internal sv_upgrade routine adds "members" to an SV, making it into a more specialized kind of SV. The top several SV types are so specialized, however, that they cannot be interconverted. This message indicates that such a conversion was attempted. (P) The undefined SV is the bottom of the totem pole, in the scheme of upgradability. Upgrading to undef indicates an error in the code calling sv_upgrade. (F) Only a simple scalar variable may be used as a loop variable on a foreach. (F) You've mixed up your reference types. You have to dereference a reference of the type needed. You can use the ref() function to test the type of the reference, if need be. (W) 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 only valid as part of a regular expression pattern. Trying to do this in ordinary Perl code produces a value that prints out looking like SCALAR(0xdecaf). Use the $1 form instead. (F) Only hard references are allowed by "strict refs". Symbolic references are disallowed. See the perlref manpage. (F) A value used as either a hard reference or a symbolic reference must be a defined value. This helps to de-lurk some insidious errors. (F) The ${name} construct is for disambiguating identifiers in strings, not in ordinary code. (F) You tried to declare a magical variable as a lexical variable. This is not allowed, because the magic can only be tied to 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. (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 an array reference, or anything else subscriptable. (F) The write routine failed for some reason while trying to process a -e switch. Maybe your /tmp partition is full, or clobbered. (F) You tried to repeat a constant value (often the undefined value) with an assignment operator, which implies modifying the value itself. Perhaps you need to copy the value to a temporary, and repeat that. (F) The create routine failed for some reaon while trying to process a -e switch. Maybe your /tmp partition is full, or clobbered. (W) A novice will sometimes say

    chmod 777, $filename
not realizing that 777 will be interpreted as a decimal number, equivalent to 01411. Octal constants are introduced with a leading 0 in Perl, as in C. (W) You tried to close a filehandle that was never opened. (W) You tried to do a connect on a closed socket. Did you forget to check the return value of your socket() call? See the connect entry in the perlfunc manpage. (P) The malloc package that comes with Perl had an internal failure. (P) The regular expression engine got confused by what the regular expression compiler gave it. (P) The regular expression engine got passed a regexp program without a valid magic number. (W) This subroutine has called itself (directly or indirectly) 100 times than it has returned. This probably indicates an infinite recursion, unless you're writing strange benchmark programs, in which case it indicates something else. (W) You probably said %hash{$key} when you meant $hash{$key} or @hash{@keys}. On the other hand, maybe you just meant %hash and got carried away. (S) This is an educated guess made in conjunction with the message "%s found where operator expected". It often means a subroutine or module name is being referenced that hasn't been declared yet. This may be because of ordering problems in your file, or because of a missing "sub", "package", "require", or "use" statement. If you're referencing something that isn't defined yet, you don't actually have to define the subroutine or package before the current location. You can use an empty "sub foo;" or "package FOO;" to enter a "forward" declaration. (P) The internal handling of magical variables has been cursed. (P) This should have been caught by safemalloc() instead. (S) An internal routine called free() on something that had already been freed. (F) An untrapped exception was raised while executing an END subroutine. The interpreter is immediately exited. (F) An error peculiar to VMS. Since Perl may have to deal with file specifications in either VMS or Unix syntax, it converts them to a single form when it must operate on them directly. Either you've passed an invalid file specification to Perl, or you've found a case the conversion routines don't handle. Drat. (F) The final summary message when a Perl compilation fails. (W) You are exiting an eval by unconventional means, such as a a goto, or a loop control statement. (W) You are exiting a subroutine by unconventional means, such as a a goto, or a loop control statement. (W) You are exiting a substitution by unconventional means, such as a a return, a goto, or a loop control statement. (P) An error peculiar to VMS. Something untoward happened in a VMS system service or RTL routine; Perl's exit status should provide more details. The filename in "at %s" and the line number in "line %d" tell you which section of the Perl source code is distressed. (F) Your machine apparently doesn't implement fcntl(). What is this, a PDP-11 or something? (W) An I/O operation was attempted on a filehandle that was never initialized. You need to do an open() or a socket() call, or call a constructor from the FileHandle package. (W) You tried to write on a read-only filehandle. If you intended it to be a read-write filehandle, you needed to open it with "+<" or "+>" or "+>>" instead of with "<" or nothing. If you only intended to write the file, use ">" or ">>". See the open entry in the perlfunc manpage. (W) You tried to write on a read-only filehandle. If you intended it to be a read-write filehandle, you needed to open it with "+<" or "+>" or "+>>" instead of with "<" or nothing. If you only intended to write the file, use ">" or ">>". See the open entry in the perlfunc manpage. (F) You must now decide whether the final $ in a string was meant to be a literal dollar sign, or was meant to introduce a variable name that happens to be missing. So you have to put either the backslash or the name. (F) You must now decide whether the final @ in a string was meant to be a literal "at" sign, or was meant to introduce a variable name that happens to be missing. So you have to put either the backslash or the name. (W) You redefined a format. To suppress this warning, say

    {
        local $^W = 0;
        eval "format NAME =...";
    }
(F) A format must be terminated by a line with a solitary dot. Perl got to the end of your file without finding such a line. (W) You said

    if ($foo = 123)
when you meant

    if ($foo == 123)
(or something like that). (S) A warning from the GDBM_File extension that a store failed. (F) Your C library apparently doesn't implement gethostent(), probably because if it did, it'd feel morally obligated to return every hostname on the Internet. (W) You tried to get a socket or peer socket name on a closed socket. Did you forget to check the return value of your socket() call? (S) A warning peculiar to VMS. The call to sys$getuai underlying the getpwnam operator returned an invalid UIC. (F) The lexer saw a left angle bracket in a place where it was expecting a term, so it's looking for the corresponding right angle bracket, and not finding it. Chances are you left some needed parentheses out earlier in the line, and you really meant a "less than". (F) You've said "use strict vars", which indicates that all variables must either be lexically scoped (using "my"), or explicitly qualified to say which package the global variable is in (using "::"). (F) Unlike with "next" or "last", you're not allowed to goto an unspecified destination. See the goto entry in the perlfunc manpage. (S) A routine asked for a symbol from a symbol table that ought to have existed already, but for some reason it didn't, and had to be created on an emergency basis to prevent a core dump. (D) Really old Perl let you omit the % on hash names in some spots. This is now heavily deprecated. (W) Typographical errors often show up as unique identifiers. If you had a good reason for having a unique identifier, then just mention it again somehow to suppress the message. (F) You tried to divide a number by 0. Either something was wrong in your logic, or you need to put a conditional in to guard against meaningless input. (F) You tried to divide a number by 0 to get the remainder. Most numbers don't take to this kindly. (F) You used an 8 or 9 in a octal number. (W) You may have tried to use an 8 or 9 in a octal number. Interpretation of the octal number stopped before the 8 or 9. (F) You tried to do something that the tainting mechanism didn't like. The tainting mechanism is turned on when you're running setuid or setgid, or when you specify -T to turn it on explicitly. The tainting mechanism labels all data that's derived directly or indirectly from the user, who is considered to be unworthy of your trust. If any such data is used in a "dangerous" operation, you get this error. See the perlsec manpage for more information. (F) You can't use system(), exec(), or a piped open in a setuid or setgid script if $ENV{PATH} contains a directory that is writable by the world. See the perlsec manpage. (F) You can't use system(), exec(), or a piped open in a setuid or setgid script if $ENV{PATH} is derived from data supplied (or potentially supplied) by the user. The script must set the path to a known value, using trustworthy data. See the perlsec manpage. (S) A warning peculiar to VMS. Perl keeps track of the number of times you've called fork and exec, in order to determine whether the current call to exec should be affect the current script or a subprocess (see the exec entry in the perlvms manpage). Somehow, this count has become scrambled, so Perl is making a guess and treating this exec as a request to terminate the Perl script and execute the specified command. (P) Something went badly wrong in the regular expression parser. (P) Something went badly awry in the regular expression parser. (F) The range specified in a character class had a minimum character greater than the maximum character. See the perlre manpage. (F) Your machine apparently doesn't implement ioctl(), which is pretty strange for a machine that supports C. (P) The regular expression parser is confused. (F) You named a loop to break out of, but you're not currently in a loop of that name, not even if you count where you were called from. See the last entry in the perlfunc manpage. (F) You named a loop to continue, but you're not currently in a loop of that name, not even if you count where you were called from. See the last entry in the perlfunc manpage. (F) You named a loop to restart, but you're not currently in a loop of that name, not even if you count where you were called from. See the last entry in the perlfunc manpage. (W) You tried to do a listen on a closed socket. Did you forget to check the return value of your socket() call? See the listen entry in the perlfunc manpage. (F) It used to be that Perl would try to guess whether you wanted an array interpolated or a literal @. It did this when the string was first used at runtime. Now strings are parsed at compile time, and ambiguous instances of @ must be disambiguated, either by putting a backslash to indicate a literal, or by declaring (or using) the array within the program before the string (lexically). (Someday it will simply assume that an unbackslashed @ interpolates an array.) (F) An attempt was made to specify an entry in an overloading table that doesn't somehow point to a valid method. See the perlovl manpage. (S) An advisory indicating that the previous error may have been caused by a missing delimiter on a string or pattern, because it eventually ended earlier on the current line. (W) An underline in a decimal constant wasn't on a 3-digit boundary. (F) Apparently you've been programming in csh too much. Variables are always mentioned with the $ in Perl, unlike in the shells, where it can vary from one line to the next. (F) While certain functions allow you to specify a filehandle or an "indirect object" before the argument list, this ain't one of them. (S) This is an educated guess made in conjunction with the message "%s found where operator expected". Often the missing operator is a comma. (F) The lexer counted more opening curly brackets (braces) than closing ones. As a general rule, you'll find it's missing near the place you were last editing. (S) This is an educated guess made in conjunction with the message "%s found where operator expected". Don't automatically put a semicolon on the previous line just because you saw this message. (F) You tried, directly or indirectly, to change the value of a constant. You didn't, of course, try "2 = 1", since the compiler catches that. But an easy way to do the same thing is:

    sub mod { $_[0] = 1 }
    mod(2);
Another way is to assign to a substr() that's off the end of the string. (F) You tried to make an array value spring into existence, and the subscript was probably negative, even counting from end of the array backwards. (F) You tried to make a hash value spring into existence, and it couldn't be created for some peculiar reason. (F) Only a bare module name is allowed as the first argument to a "use". (F) You don't have System V message IPC on your system. (W) Multidimensional arrays aren't written like $foo[1,2,3]. They're written like $foo[1][2][3], as in C. (F) You tried to do a read/write/send/recv operation with a buffer length that is less than 0. This is difficult to imagine. (F) You can't quantify a quantifier without intervening parens. So things like ** or +* or ?* are illegal.

Note, however, that the minimal matching quantifiers, *?, +? and ?? appear to be nested quantifiers, but aren't. See the perlre manpage. (F) The setuid emulator requires that scripts have a well-formed #! line even on machines that don't support the #! construct. (F) Certain operations are deemed to be too insecure for a setuid or setgid script to even be allowed to attempt. Generally speaking there will be another way to do what you want that is, if not secure, at least securable. See the perlsec manpage. (F) A setuid script can't be specified by the user. (F) A list operator that has a filehandle or "indirect object" is not allowed to have a comma between that and the following arguments. Otherwise it'd be just another one of the arguments. (F) An error peculiar to VMS. Perl handles its own command line redirection, and found a '|' at the end of the command line, so it doesn't know whither you want to pipe the output from this command. (F) The currently executing code was compiled with the -d switch, but for some reason the perl5db.pl file (or some facsimile thereof) didn't define a routine to be called at the beginning of each statement. Which is odd, because the file should have been required automatically, and should have blown up the require if it didn't parse right. (P) This is counted as an internal error, because every machine should supply dbm nowadays, since Perl comes with SDBM. See the SDBM_File manpage. (F) The currently executing code was compiled with the -d switch, but for some reason the perl5db.pl file (or some facsimile thereof) didn't define a DB::sub routine to be called at the beginning of each ordinary subroutine call. (F) An error peculiar to VMS. Perl handles its own command line redirection, and found a '2>' or a '2>>' on the command line, but can't find the name of the file to which to write data destined for stderr. (F) An error peculiar to VMS. Perl handles its own command line redirection, and found a '<' on the command line, but can't find the name of the file from which to read data for stdin. (F) An error peculiar to VMS. Perl handles its own command line redirection, and found a lone '>' at the end of the command line, so it doesn't know whither you wanted to redirect stdout. (F) An error peculiar to VMS. Perl handles its own command line redirection, and found a '>' or a '>>' on the command line, but can't find the name of the file to which to write data destined for stdout. (F) You called perl -x, but no line was found in the file beginning with #! and containing the word "perl". (F) Configure didn't find anything resembling the setregid() call for your system. (F) Configure didn't find anything resembling the setreuid() call for your system. (F) The argument to -I must follow the -I immediately with no intervening space. (P) An error peculiar to VMS. The internal routine my_pclose() tried to close a pipe which hadn't been opened. This should have been caught earlier as an attempt to close an unopened filehandle. (W) You specified a signal name as a subscript to %SIG that was not recognized. Say kill -l in your shell to see the valid signal names on your system. (F) Perl was trying to evaluate a reference to a code value (that is, a subroutine), but found a reference to something else instead. You can use the ref() function to find out what kind of ref it really was. See also the perlref manpage. (F) I'm not sure how you managed to generate a reference to an anonymous format, but this indicates you did, and that it didn't exist. (F) Perl was trying to evaluate a reference to a "type glob" (that is, a symbol table entry that looks like *foo), but found a reference to something else instead. You can use the ref() function to find out what kind of ref it really was. See the perlref manpage. (F) Perl was trying to evaluate a reference to a hash value, but found a reference to something else instead. You can use the ref() function to find out what kind of ref it really was. See the perlref manpage. (F) The setuid emulator requires that scripts have a well-formed #! line even on machines that don't support the #! construct. The line must mention perl. (F) Perl was trying to evaluate a reference to a scalar value, but found a reference to something else instead. You can use the ref() function to find out what kind of ref it really was. See the perlref manpage. (F) Perl was trying to evaluate a reference to a code value (that is, a subroutine), but found a reference to something else instead. You can use the ref() function to find out what kind of ref it really was. See also the perlref manpage. (F) An attempt was made to specify an entry in an overloading table that doesn't somehow point to a valid subroutine. See the perlovl manpage. (F) Perl was trying to evaluate a reference to an array value, but found a reference to something else instead. You can use the ref() function to find out what kind of ref it really was. See the perlref manpage. (F) The function requires more arguments than you specified. (W) A format specified more picture fields than the next line supplied. See the perlform manpage. (F) You can't require the null filename, especially since on many machines that means the current directory! See the require entry in the perlfunc manpage. (P) Some internal routine called run() with a null opcode pointer. (P) An attempt was made to realloc NULL. (P) The internal pattern matching routines blew it bigtime. (P) The internal pattern matching routines are out of their gourd. (S) You specified an odd number of elements to a hash list, which is odd, since hash lists come in key/value pairs. (S) An internal warning that the grammar is screwed up. (S) An internal warning that the grammar is screwed up. (F) An attempt was made to use an entry in an overloading table that somehow no longer points to a valid method. See the perlovl manpage. (S) You used a variable or subroutine call where the parser was expecting an operator. The parser has assumed you really meant to use an operator, but this is highly likely to be incorrect. For example, if you say "*foo *foo" it will be interpreted as if you said "*foo * 'foo'". (F) The yacc parser wanted to grow its stack so it could continue parsing, but realloc() wouldn't give it more memory, virtual or otherwise. (X) The malloc() function returned 0, indicating there was insufficient remaining memory (or virtual memory) to satisfy the request. (W) A single call to write() produced more lines than can fit on a page. See the perlform manpage. (P) Failed an internal consistency check trying to compile a grep. (P) Failed an internal consistency check trying to compile a split. (P) The savestack was requested to restore more localized values than there are in the savestack. (P) We popped the context stack to an eval context, and then discovered it wasn't an eval context. (P) The internal pp_match() routine was called with invalid operational data. (P) Something terrible went wrong in setting up for the split. (P) The internal pp_subst() routine was called with invalid operational data. (P) The internal do_trans() routine was called with invalid operational data. (P) We popped the context stack to a context with the specified label, and then discovered it wasn't a context we know how to do a goto in. (P) The lexer got into a bad state at a case modifier. (P) The lexer got into a bad state parsing a string with brackets. (P) We popped the context stack to a block context, and then discovered it wasn't a block context. (P) A writable lexical variable became readonly somehow within the scope. (P) The savestack probably got out of sync. At least, there was an invalid enum on the top of it. (P) Something requested a negative number of bytes of malloc. (P) The compiler is screwed up with respect to the map() function. (P) One of the internal array routines was passed a null AV pointer. (P) The compiler got confused about which scratch pad it was allocating and freeing temporaries and lexicals from. (P) The compiler got confused about which scratch pad it was allocating and freeing temporaries and lexicals from. (P) An invalid scratch pad offset was detected internally. (P) The compiler got confused about which scratch pad it was allocating and freeing temporaries and lexicals from. (P) An invalid scratch pad offset was detected internally. (P) The compiler got confused about which scratch pad it was allocating and freeing temporaries and lexicals from. (P) An invalid scratch pad offset was detected internally. (P) The foreach iterator got called in a non-loop context frame. (P) Something requested a negative number of bytes of realloc. (P) Some internal routine requested a goto (or something like it), and didn't supply the destination. (P) We popped the context stack to a subroutine or eval context, and then discovered it wasn't a subroutine or eval context. (P) scan_num() got called on something that wasn't a number. (P) The sv_insert() routine was told to remove more string than there was string. (P) The compiler attempted to do a goto, or something weird like that. (P) The lexer got into a bad state while processing a case modifier. (W) You said something like

    my $foo, $bar = @_;
when you meant

    my ($foo, $bar) = @_;
Remember that "my" and "local" bind closer than comma. (F) The module in question uses features of a version of Perl more recent than the currently running version. How long has it been since you upgraded, anyway? See the require entry in the perlfunc manpage. (F) The setuid emulator in suidperl decided you were up to no good. (W) A warning peculiar to VMS. Waitpid() was asked to wait for a process which isn't a subprocess of the current process. While this is fine from VMS' perspective, it's probably not what you intended. (F) Your C compiler uses POSIX getpgrp(), which takes no argument, unlike the BSD version, which takes a pid. (F) An ioctl() or fcntl() returned more than Perl was bargaining for. Perl guesses a reasonable buffer size, but puts a sentinel byte at the end of the buffer just in case. This sentinel byte got clobbered, and Perl assumes that memory is now corrupted. See the ioctl entry in the perlfunc manpage. (S) The old irregular construct

    open FOO || die;

is now misinterpreted as

    open(FOO || die);
because of the strict regularization of Perl 5's grammar into unary and list operators. (The old open was a little of both.) You must put parens around the filehandle, or use the new "or" operator instead of "||". (W) The filehandle you're printing on got itself closed sometime before now. Check your logic flow. (W) The filehandle you're writing to got itself closed sometime before now. Check your logic flow. (W) The compiler found a bare word where it expected a conditional, which often indicates that an || or && was parsed as part of the last argument of the previous construct, for example:

    open FOO || die;
(W) The filehandle you're reading from got itself closed sometime before now. Check your logic flow. (F) You can't allocate more than 64K on an MSDOS machine. (F) You can't use the -D option unless the code to produce the desired output is compiled into Perl, which entails some overhead, which is why it's currently left out of your copy. (F) More than 100 levels of inheritance were used. Probably indicates an unintended loop in your inheritance hierarchy. (W) The internal sv_replace() function was handed a new SV with a reference count of other than 1. (P) The regular expression engine got confused by what the regular expression compiler gave it. (P) A "can't happen" error, because safemalloc() should have caught it earlier. (F) The current implementation of regular expression uses shorts as address offsets within a string. Unfortunately this means that if the regular expression compiles to longer than 32767, it'll blow up. Usually when you want a regular expression this big, there is a better way to do it with multiple statements. See the perlre manpage. (W) You wrote your assignment operator backwards. The = must always comes last, to avoid ambiguity with subsequent unary operators. (F) Your format contained the ~~ repeat-until-blank sequence, but it produced 200 lines at once, and the 200th line looked exactly like the 199th line. Apparently you didn't arrange for the arguments to exhaust themselves, either by using ^ instead of @ (for scalar variables), or by shifting or popping (for array variables). See the perlform manpage. (W) You've used an array slice (indicated by @) to select a single value of an array. Generally it's better to ask for a scalar value (indicated by $). The difference is that $foo[&bar] always behaves like a scalar, both when assigning to it and when evaluating its argument, while @foo[&bar] behaves like a list when you assign to it, and provides a list context to its subscript, which can do weird things if you're only expecting one subscript.

On the other hand, if you were actually hoping to treat the array element as a list, you need to look into how references work, since Perl will not magically convert between scalars and lists for you. See the perlref manpage. (F) Oddly, the suidperl program was invoked on a script with its setuid or setgid bit set. This doesn't make much sense. (F) The lexer couldn't find the final delimiter of a // or m{} construct. Remember that bracketing delimiters count nesting level. (W) You tried to use the seek() function on a filehandle that was either never opened or has been closed since. (F) This machine doesn't implement the select() system call. (F) You don't have System V semaphore IPC on your system. (S) The internal newSVsv() routine was called to duplicate a scalar that had previously been marked as free. (W) A nearby syntax error was probably caused by a missing semicolon, or possibly some other missing operator, such as a comma. (W) The filehandle you're sending to got itself closed sometime before now. Check your logic flow. (F) A regular expression comment must be terminated by a closing parenthesis. Embedded parens aren't allowed. See the perlre manpage. (F) A proposed regular expression extension has the character reserved but has not yet been written. See the perlre manpage. (F) You used a regular expression extension that doesn't make sense. See the perlre manpage. (F) You tried to assign to $), and your operating system doesn't support the setegid() system call (or equivalent), or at least Configure didn't think so. (F) You tried to assign to $>, and your operating system doesn't support the seteuid() system call (or equivalent), or at least Configure didn't think so. (F) You tried to assign to $(, and your operating system doesn't support the setrgid() system call (or equivalent), or at least Configure didn't think so. (F) You tried to assign to $<, and your operating system doesn't support the setruid() system call (or equivalent), or at least Configure didn't think so. (F) The setuid emulator won't run a script that is writable by the world, because the world might have written on it already. (F) You don't have System V shared memory IPC on your system. (W) You tried to do a shutdown on a closed socket. Seems a bit superfluous. (W) The signal handler named in %SIG doesn't, in fact, exist. Perhaps you put it into the wrong package? (F) An ancient error message that almost nobody ever runs into anymore. But before sort was a keyword, people sometimes used it as a filehandle. (F) A sort comparison routine must return a number. You probably blew it by not using C<<=> or cmp, or by not using them correctly. See the sort entry in the perlfunc manpage. (F) A sort comparison subroutine may not return a list value with more or less than one element. See the sort entry in the perlfunc manpage. (P) The split was looping infinitely. (Obviously, a split shouldn't iterate more times than there are characters of input, which is what happened.) See the split entry in the perlfunc manpage. (W) You tried to use the stat() function (or an equivalent file test) on a filehandle that was either never opened or has been closed since. (W) You did an exec() with some statement after it other than a die(). This is almost always an error, because exec() never returns unless there was a failure. You probably wanted to use system() instead, which does return. To suppress this warning, put the exec() in a block by itself. (W) You redefined a subroutine. To suppress this warning, say

    {
        local $^W = 0;
        eval "sub name { ... }";
    }
(P) The substitution was looping infinitely. (Obviously, a substitution shouldn't iterate more times than there are characters of input, which is what happened.) See the discussion of substitution in the section on Quote and Quotelike Operators in the perlop manpage. (F) The lexer couldn't find the interior delimiter of a s/// or s{}{} construct. Remember that bracketing delimiters count nesting level. (F) The lexer couldn't find the final delimiter of a s/// or s{}{} construct. Remember that bracketing delimiters count nesting level. (W) You tried to reference a substr() that pointed outside of a string. That is, the absolute value of the offset was larger than the length of the string. See the substr entry in the perlfunc manpage. (F) Your Perl was compiled with -DSETUID_SCRIPTS_ARE_SECURE_NOW, but a version of the setuid emulator somehow got run anyway. (F) Probably means you had a syntax error. Common reasons include:

    A keyword is misspelled.
    A semicolon is missing.
    A comma is missing.
    An opening or closing parenthesis is missing.
    An opening or closing brace is missing.
    A closing quote is missing.
Often there will be another error message associated with the syntax error giving more information. (Sometimes it helps to turn on -w.) The error message itself often tells you where it was in the line when it decided to give up. Sometimes the actual error is several tokens before this, since Perl is good at understanding random input. Occasionally the line number may be misleading, and once in a blue moon the only way to figure out what's triggering the error is to call perl -c repeatedly, chopping away half the program each time to see if the error went away. Sort of the cybernetic version of 20 questions. (F) You tried to do something with a function beginning with "sem", "shm" or "msg". See the semctl entry in the perlfunc manpage, for example. (W) The filehandle you're writing to got itself closed sometime before now. Check your logic flow. (W) You tried to use the tell() function on a filehandle that was either never opened or has been closed since. (W) You tried to invoke a file test operator on a filehandle that isn't open. Check your logic. See also the section on -X in the perlfunc manpage. (F) Assignment to $[ is now strictly circumscribed, and interpreted as a compiler directive. You may only say one of

    $[ = 0;
    $[ = 1;
    ...
    local $[ = 0;
    local $[ = 1;
    ...
This is to prevent the problem of one module changing the array base out from under another module inadvertently. See the section on $[ in the perlvar manpage. The function indicated isn't implemented on this architecture, according to the probings of Configure. (F) Configure couldn't find the crypt() function on your machine, probably because your vendor didn't supply it, probably because they think the U.S. Govermnment thinks it's a secret, or at least that they will continue to pretend that it is. And if you quote me on that, I will deny it. (F) It makes no sense to test the current stat buffer for symbolic linkhood if the last stat that wrote to the stat buffer already went past the symlink to get to the real file. Use an actual filename instead. (F) Your version of the C library apparently doesn't do times(). I suspect you're not running on Unix. (F) There has to be at least one argument to syscall() to specify the system call to call, silly dilly. (F) Perl only supports a maximum of 14 args to syscall(). (F) The function requires fewer arguments than you specified. (F) The regular expression ends with an unbackslashed backslash. Backslash it. See the perlre manpage. (F) The lexer couldn't find the interior delimiter of a tr/// or tr[][] construct. (F) The lexer couldn't find the final delimiter of a tr/// or tr[][] construct. (F) Your machine doesn't implement a file truncation mechanism that Configure knows about. (F) This function requires the argument in that position to be of a certain type. Arrays must be @NAME or @{EXPR}. Hashes must be %NAME or %{EXPR}. No implicit dereferencing is allowed--use the {EXPR} forms as an explicit dereference. See the perlref manpage. (W) A umask of 222 is incorrect. It should be 0222, since octal literals always start with 0 in Perl, as in C. (W) The exit code detected an internal inconsistency in how many execution contexts were entered and left. (W) The exit code detected an internal inconsistency in how many values were temporarily localized. (W) The exit code detected an internal inconsistency in how many blocks were entered and left. (W) The exit code detected an internal inconsistency in how many mortal scalars were allocated and freed. (F) The format indicated doesn't seem to exist. Perhaps it's really in another package? See the perlform manpage. (F) The sort comparison routine specified doesn't seem to exist. Perhaps it's in a different package? See the sort entry in the perlfunc manpage. (F) The subroutine indicated hasn't been defined, or if it was, it has since been undefined. (F) The anonymous subroutine you're trying to call hasn't been defined, or if it was, it has since been undefined. (F) The sort comparison routine specified is declared but doesn't seem to have been defined yet. See the sort entry in the perlfunc manpage. (F) The unexec() routine failed for some reason. See your local FSF representative, who probably put it there in the first place. (F) There are no byteswapping functions for a machine with this byte order. (F) Unbackslashed parentheses must always be balanced in regular expressions. If you're a vi user, the % key is valuable for finding the matching paren. See the perlre manpage. (F) The lexer counted more closing curly brackets (braces) than opening ones, so you're probably missing an opening bracket. As a general rule, you'll find the missing one (so to speak) near the place you were last editing. (F) The brackets around a character class must match. If you wish to include a closing bracket in a character class, backslash it or put it first. See the perlre manpage. (W) You used a bare word that might someday be claimed as a reserved word. It's best to put such a word in quotes, or capitalize it somehow, or insert an underbar into it. You might also declare it as a subroutine. (S) A garbage character was found in the input, and ignored, in case it's a weird control character on an EBCDIC machine, or some such. (F) You specified a signal name to the kill() function that was not recognized. Say kill -l in your shell to see the valid signal names on your system. (F) You specified an illegal option to Perl. Don't do that. (If you think you didn't do that, check the #! line to see if it's supplying the bad switch on your behalf.) (W) A file operation was attempted on a filename, and that operation failed, PROBABLY because the filename contained a newline, PROBABLY because you forgot to chop() or chomp() it off. See the chop entry in the perlfunc manpage. (F) Your machine doesn't support opendir() and readdir(). (F) This machines doesn't implement the indicated function, apparently. At least, Configure doesn't think so. (F) Your machine doesn't support the Berkeley socket mechanism, or at least that's what Configure thought. (F) The lexer saw a left angle bracket in a place where it was expecting a term, so it's looking for the corresponding right angle bracket, and not finding it. Chances are you left some needed parentheses out earlier in the line, and you really meant a "less than". (D) This was an ill-advised attempt to emulate a poorly defined awk feature. Use an explicit printf() or sprintf() instead. (D) This variable magically turned on multiline pattern matching, both for you and for any luckless subroutine that you happen to call. You should use the new //m and //s modifiers now to do that without the dangerous action-at-a-distance effects of $*. (F) You attempted to use a feature of printf that is accessible only from C. This usually means there's a better way to do it in Perl. (D) The construct indicated is no longer recommended for use, generally because there's a better way to do it, and also because the old way has bad side effects. (D) It makes a lot of work for the compiler when you clobber a subroutine's argument list, so it's better if you assign the results of a split() explicitly to an array (or list). (W) An undefined value was used as if it were already defined. It was interpreted as a "" or a 0, but maybe it was a mistake. To suppress this warning assign an initial value to your variables. (W) You did something without a side effect in a context that does nothing with the return value, such as a statement that doesn't return a value from a block, or the left side of a scalar comma operator. Very often this points not to stupidity on your part, but a failure of Perl to parse your program the way you thought it would. For example, you'd get this if you mixed up your C precedence with Python precedence and said

    $one, $two = 1, 2;
when you meant to say

    ($one, $two) = (1, 2);
Another common error is to use ordinary parentheses to construct a list reference when you should be using square or curly brackets, for example, if you say

    $array = (1,2);
when you should have said

    $array = [1,2];
The square brackets explicitly turn a list value into a scalar value, while parentheses do not. So when a parenthesized list is evaluated in a scalar context, the comma is treated like C's comma operator, which throws away the left argument, which is not what you want. See the perlref manpage for more on this. (S) The implicit close() done by an open() got an error indication on the close(0. This usually indicates your filesystem ran out of disk space. (S) You wrote a unary operator followed by something that looks like a binary operator that could also have been interpreted as a term or unary operator. For instance, if you know that the rand function has a default argument of 1.0, and you write

    rand + 5;
you may THINK you wrote the same thing as

    rand() + 5;
but in actual fact, you got

    rand(+5);
So put in parens to say what you really mean. (W) The filehandle you're writing to got itself closed sometime before now. Check your logic flow. (F) You had a pack template that specified a relative position before the beginning of the string being unpacked. See the pack entry in the perlfunc manpage. (F) You had a pack template that specified a relative position after the end of the string being unpacked. See the pack entry in the perlfunc manpage. (F) The use of an external subroutine as a sort comparison is not yet supported. (F) The use of an external subroutine as a sort comparison is not yet supported. (F) A filehandle represents an opened file, and when you opened the file it already went past any symlink you are presumably trying to look for. Use a filename instead. (F) And you probably never will, since you probably don't have the sources to your kernel, and your vendor probably doesn't give a rip about what you want. Your best bet is to use the wrapsuid script in the eg directory to put a setuid C wrapper around your script. (W) You assigned a bareword as a signal handler name. Unfortunately, you already have a subroutine of that name declared, which means that Perl 5 will try to call the subroutine when the assignment is executed, which is probably not what you want. (If it IS what you want, put an & in front.) (W) You tried to get or set a socket option on a closed socket. Did you forget to check the return value of your socket() call? See the getsockopt entry in the perlfunc manpage. (W) Outside of patterns, backreferences live on as variables. The use of backslashes is grandfathered on the righthand side of a substitution, but stylistically it's better to use the variable form because other Perl programmers will expect it, and it works better if there are more than 9 backreferences. (F) An error peculiar to VMS. Perl does its own command line redirection, and found that STDIN was a pipe, and that you also tried to redirect STDIN using '<'. Only one STDIN stream to a customer, please. (F) An error peculiar to VMS. Perl does its own command line redirection, and thinks you tried to redirect stdout both to a file and into a pipe to another command. You need to choose one or the other, though nothing's stopping you from piping into a program or Perl script which 'splits' output into two streams, such as

    open(OUT,">$ARGV[0]") or die "Can't write to $ARGV[0]: $!";
    while (<STDIN>) {
        print;
        print OUT;
    }
    close OUT;