Errata

The comma at the end of the line

"Sat" => "Saturday",

should be deleted. It's not really wrong, but it looks bad.

The line that reads:

$val ||= "2"; #Set $val to 2 if it isn't already set.

is misleading because it will also set $val to 2 if $val is already set to 0.
It should read:

$val ||= "2"; #Set $val to 2 if it isn't already set or set to 0.

($file) = <blurch*>; # list context
should be
(@file) = <blurch*>; # list context

Second to last entry in table is (?...), should be (?=...)

The example for finding duplicate words will not work for single character
words.

For example:

"The example has a a mistake in it and won't catch this line."
"Nor this 1 1."

The offending fragment is line 8 of the example--it picks up only words of 2
or more characters:

(wS+) # find wordish chunk

Either of these work:

(wS*) # find wordish chunk
(S+) # find wordish chunk

(77, 90, and index (and elsewhere?):
There's no documentation for the range operator ... (as distinct from ..).
It's in the online documentation for Perl 5.005 and it's mentioned in
"Perl Cookbook" recipe 6.8.

"There is also a logical xor operator that has no exact counterpart in C or
perl, ...."

If "xor" is in the perl language, there _is_ an exact counterpart, isn't there?

In the paragraph beginning "You might think it odd," the word "foreach's"
should be changed to "for's".

This example reads

($aref, $bref) = func(@c, @d);
print "@$aref has more than @$bref
";
...

However, if @c has the same number of elements as @d, then the text of the
print statement will be incorrect. Instead, it could read

print "@$aref has at least as many as @$bref
";

There is a program listed:

1) sub try (&$) {
2) my($try,$catch) = @_;
3) eval { &$try };
4) if ($@) {
5) local $_ = $@;
6) &$catch;
7) }
8) }
9) sub catch (&) { @_ }
10)
11) try {
12) die "phooey";
13) } catch {
14) /phooey/ and print "unphooey
";
15) };

If you run this program, you'll receive an run-time error something like this:

=====
Undefined subroutine &main::1 called at ./test.pl line 8.
=====

This is because of the prototype on subroutine "try".

Line 1) The prototype (&$) forces the second parameter to be in scalar context.

Line 9) "catch" returns the array of its parameters, @_. That array is then
passed to try in scalar context. When an array is passed in scalar context, it
returns the number of elements on the array.

Line 2) So then the variable $catch in the subroutine "try" actually does not
contain a subroutine reference but a scalar "1".

Line 6) When &$catch is called, perl treats this as a symbolic reference to a
subroutine named 1. Since there is no subroutine in the main namespace named
1, perl dies with an error.

This can be fixed in a number of ways. (TMTOWTDI :) ) Two of the ways that
will keep from changing the main executable program are:

==========
*) Change Line 1:

Line 1) sub try (&@) {

+++) This will cause perl to pass the array returned by catch in list context.
Passing an array in list context will maintain all of the elements, so the
original subroutine reference is actually passed correctly to try.
==========

OR (really this should be an AND/OR, but I think OR is more appropriate here)

==========
*) Change Line 9:

Line 9) sub catch (&) { $_[0] }

+++ By returning a scalar, nothing is lost when the scalar returned by catch
is passed in scalar context to subroutine try. The function reference actually
gets passed and the program runs.
==========

Personally I like the former change better than the latter. If it were me, I
would make the first change and then make a special note saying that if that
second parameter were a scalar then the program would have a run-time error.
(And then point out why)

I feel that this is an important correction as it can confuse the reader who
is new to perl prototypes. (Because this error is a GREAT example of how the $
scalar prototype FORCES the second parameter into scalar context)

The current value of the inplace-edit extension. Use undef to disable
inplace editing. (Mnemonic: value of -i switch).

What this doesn't say explicitly is that if you _set_ $^I you _enable_ inplace
editing.

The text as written can be interpreted as meaning that you must use the -i
switch, at which point the value of $^I contains the value of the extension
named with the switch (e.g. -i.bak) and undefing $^I disables inplace editing
at that point. It would be helpful to include text to the effect that you
don't need to use -i _iff_ you set $^I instead.

that are not described in "Perl Functions in Alphabetical Order":

- Flow of program control: continue
- Fetching user and group information: entgrent, endhotsnt, endnetent,
endpwent, setgrent, setpwent
- Fetching network information: endproent, endservent, sethostent,
setnetent, setprotoent, setservent

eval "$$arrayname{$key} = 1";

This doesnt work! If $arrayname isnt a hash(which it shouldnt be), Perl
expands that to:

eval "$ = 1";

Which perl does not like at all. A bit of experimenting proves the correct
syntax to be:

eval "$$arrayname{$key} = 1";

Effectively keeping perl from expanding "arrayname" as a hash.

In the sample fcntl call, &F_SETFL should be &F_SETFD.

Also, the preceding statement that "Perl always sets the close-on-exec flag
for file descriptors above 2" appears to be incorrect for version 5.004_04.
Using this bit of code:

pipe PARENT_READER, CHILD_WRITER;
fcntl CHILD_WRITER, &F_SETFD, 1;
($pid = fork) >= 0 or die "fork: $!";
if($pid == 0) {
close PARENT_READER;
exec @ARGV or do { print CHILD_WRITER " "; exit 1; }
}
close CHILD_WRITER;
(read PARENT_READER, $childError, 1 > 0) and exit 1;

The parent process blocks on the read if the fcntl call is removed (i.e.
CHILD_WRITER appears to remain open in the exec'ed process).

in the first addition:

join
$_ =join':',($login,$passwd,etc);

second addition:

$_ =join':',$login,$passwd,etc;

The first one works; the latter does not.

open(FOO, "|tr '[a-z]' '[A-Z]'");
open(FOO, "|-") or exec 'tr', '[a-z]', '[A-Z]';

open(FOO, "cat -n file |");
open(FOO, "-|") or exec 'cat', '-n', 'file';

does not match the code on the WebMaster CD-ROM. In particular the following,
"or" in line 2 and line 4 should be "||".

The syntax description was "corrected", and though the change certainly makes
the syntax clearer, it now renders the description's comparison to
print/sprintf incorrect (where does the format go?).

the code:

@args = ("command", "arg1", "arg2");
system(@args) == 0
or die "system @args failed: $?"

is not terminated with a semicolon.

For example, the following computes the same number as the System V sum
program:

undef $/;
$checksum = unpack ("%32C*", <>) % 32767;

For the System V systems that I have access to, the modulus should be 65535.
This is also the same number as produced by the berkeley 'cksum -o 2'.

foreach $i ( 0 .. $#{ $HoL{$family} ) {

should be

foreach $i ( 0 .. $#{ $HoL{$family} } ) {

# print the whole thing
foreach $family ( keys %TV ) {
print "the $family";
print " is on during @{ $TV{$family}{nights} }
";
print "its members are:
";
for $who ( @{ $TV{$family}{members} } ) {
print " $who->{name} ($who->{role}), age $who->{age}
";
}
- --> print "it turns out that $TV{$family}{lead} has ";
print scalar ( @{ $TV{$family}{kids} } ), " kids named ";
print join (", ", map { $_->{name} } @{ $TV{$family}{kids} } );
print "
";
print "
";
}

It gave me this error with Perl 5.005_3:

Use of uninitialized value at ./p275 line 68.

I was able to correct it via changing the line to a for loop as follows:

# print the whole thing
foreach $family ( keys %TV ) {
print "the $family";
print " is on during @{ $TV{$family}{nights} }
";
print "its members are:
";
for $who ( @{ $TV{$family}{members} } ) {
print " $who->{name} ($who->{role}), age $who->{age}
";
}
- --> for $who ( @{ $TV{$family}{members} } ) {
- --> if ( $who->{role} eq "lead" ) {
- --> print "it turns out that $who->{name} has ";
- --> last;
- --> }
- --> }
- --> #print "it turns out that $TV{$family}{'lead'} has ";
print scalar ( @{ $TV{$family}{kids} } ), " kids named ";
print join (", ", map { $_->{name} } @{ $TV{$family}{kids} } );
print "
";
print "
";
}

print CLIENT "Hello there, $name ....

It should read

print Client "Hello there, $name ....

The non-forking server contains a call to REAPER on the SIG{CHLD} handle, even
though that code is not in the non-forking version, and that version never
spawns any children.

compile on its own. The authors mention this after the code, but I missed it
the first time. The example should either be more vague (don't have the
shebang which suggests that the code is complete) or more explicit. Also, the
$paddr variable is not declared.

The value of $path in the example should have a "/" at the end. Should read:

$path eq '/virgil/aeneid/',

line reads:

chdired to $File::Find::dir when find() is called.

It should read:

chdired to $File::Find::dir when wanted() is called.

are not described elsewhere.

This is in the second edition:

$opt_foo = 'blech'

should be

$foo = 'blech'

"$keyword{$_}" should be "$keywords{$_}".