NAME

Esjis - Run-time routines for Sjis.pm

SYNOPSIS

use Esjis;

  Esjis::split(...);
  Esjis::tr(...);
  Esjis::chop(...);
  Esjis::index(...);
  Esjis::rindex(...);
  Esjis::lc(...);
  Esjis::lc_;
  Esjis::lcfirst(...);
  Esjis::lcfirst_;
  Esjis::uc(...);
  Esjis::uc_;
  Esjis::ucfirst(...);
  Esjis::ucfirst_;
  Esjis::fc(...);
  Esjis::fc_;
  Esjis::ignorecase(...);
  Esjis::capture(...);
  Esjis::chr(...);
  Esjis::chr_;
  Esjis::X ...;
  Esjis::X_;
  Esjis::glob(...);
  Esjis::glob_;
  Esjis::lstat(...);
  Esjis::lstat_;
  Esjis::opendir(...);
  Esjis::stat(...);
  Esjis::stat_;
  Esjis::unlink(...);
  Esjis::chdir(...);
  Esjis::do(...);
  Esjis::require(...);
  Esjis::telldir(...);

# "no Esjis;" not supported

ABSTRACT

This module is a run-time routines of the Sjis.pm. Because the Sjis.pm automatically uses this module, you need not use directly.

BUGS AND LIMITATIONS

I have tested and verified this software using the best of my ability. However, a software containing much regular expression is bound to contain some bugs. Thus, if you happen to find a bug that's in Sjis software and not your own program, you can try to reduce it to a minimal test case and then report it to the following author's address. If you have an idea that could make this a more useful tool, please let everyone share it.

HISTORY

This Esjis module first appeared in ActivePerl Build 522 Built under MSWin32 Compiled at Nov 2 1999 09:52:28

AUTHOR

INABA Hitoshi <ina@cpan.org>

This project was originated by INABA Hitoshi. For any questions, use <ina@cpan.org> so we can share this file.

LICENSE AND COPYRIGHT

This module is free software; you can redistribute it and/or modify it under the same terms as Perl itself. See perlartistic.

This program is distributed in the hope that it will be useful, but WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.

EXAMPLES

Split string

@split = Esjis::split(/pattern/,$string,$limit);
@split = Esjis::split(/pattern/,$string);
@split = Esjis::split(/pattern/);
@split = Esjis::split('',$string,$limit);
@split = Esjis::split('',$string);
@split = Esjis::split('');
@split = Esjis::split();
@split = Esjis::split;

This subroutine scans a string given by $string for separators, and splits the
string into a list of substring, returning the resulting list value in list
context or the count of substring in scalar context. Scalar context also causes
split to write its result to @_, but this usage is deprecated. The separators
are determined by repeated pattern matching, using the regular expression given
in /pattern/, so the separators may be of any size and need not be the same
string on every match. (The separators are not ordinarily returned; exceptions
are discussed later in this section.) If the /pattern/ doesn't match the string
at all, Esjis::split returns the original string as a single substring, If it
matches once, you get two substrings, and so on. You may supply regular
expression modifiers to the /pattern/, like /pattern/i, /pattern/x, etc. The
//m modifier is assumed when you split on the pattern /^/.

If $limit is specified and positive, the subroutine splits into no more than that
many fields (though it may split into fewer if it runs out of separators). If
$limit is negative, it is treated as if an arbitrarily large $limit has been
specified If $limit is omitted or zero, trailing null fields are stripped from
the result (which potential users of pop would do wel to remember). If $string
is omitted, the subroutine splits the $_ string. If /pattern/ is also omitted or
is the literal space, " ", the subroutine split on whitespace, /\s+/, after
skipping any leading whitespace.

A /pattern/ of /^/ is secretly treated if it it were /^/m, since it isn't much
use otherwise.

String of any length can be split:

@chars  = Esjis::split(//,  $word);
@fields = Esjis::split(/:/, $line);
@words  = Esjis::split(" ", $paragraph);
@lines  = Esjis::split(/^/, $buffer);

A pattern capable of matching either the null string or something longer than
the null string (for instance, a pattern consisting of any single character
modified by a * or ?) will split the value of $string into separate characters
wherever it matches the null string between characters; nonnull matches will
skip over the matched separator characters in the usual fashion. (In other words,
a pattern won't match in one spot more than once, even if it matched with a zero
width.) For example:

print join(":" => Esjis::split(/ */, "hi there"));

produces the output "h:i:t:h:e:r:e". The space disappers because it matches
as part of the separator. As a trivial case, the null pattern // simply splits
into separate characters, and spaces do not disappear. (For normal pattern
matches, a // pattern would repeat the last successfully matched pattern, but
Esjis::split's pattern is exempt from that wrinkle.)

The $limit parameter splits only part of a string:

my ($login, $passwd, $remainder) = Esjis::split(/:/, $_, 3);

We encourage you to split to lists of names like this to make your code
self-documenting. (For purposes of error checking, note that $remainder would
be undefined if there were fewer than three fields.) When assigning to a list,
if $limit is omitted, Perl supplies a $limit one larger than the number of
variables in the list, to avoid unneccessary work. For the split above, $limit
would have been 4 by default, and $remainder would have received only the third
field, not all the rest of the fields. In time-critical applications, it behooves
you not to split into more fields than you really need. (The trouble with
powerful languages it that they let you be powerfully stupid at times.)

We said earlier that the separators are not returned, but if the /pattern/
contains parentheses, then the substring matched by each pair of parentheses is
included in the resulting list, interspersed with the fields that are ordinarily
returned. Here's a simple example:

Esjis::split(/([-,])/, "1-10,20");

which produces the list value:

(1, "-", 10, ",", 20)

With more parentheses, a field is returned for each pair, even if some pairs
don't match, in which case undefined values are returned in those positions. So
if you say:

Esjis::split(/(-)|(,)/, "1-10,20");

you get the value:

(1, "-", undef, 10, undef, ",", 20)

The /pattern/ argument may be replaced with an expression to specify patterns
that vary at runtime. As with ordinary patterns, to do run-time compilation only
once, use /$variable/o.

As a special case, if the expression is a single space (" "), the subroutine
splits on whitespace just as Esjis::split with no arguments does. Thus,
Esjis::split(" ") can be used to emulate awk's default behavior. In contrast,
Esjis::split(/ /) will give you as many null initial fields as there are
leading spaces. (Other than this special case, if you supply a string instead
of a regular expression, it'll be interpreted as a regular expression anyway.)
You can use this property to remove leading and trailing whitespace from a
string and to collapse intervaning stretches of whitespace into a single
space:

$string = join(" ", Esjis::split(" ", $string));

The following example splits an RFC822 message header into a hash containing
$head{'Date'}, $head{'Subject'}, and so on. It uses the trick of assigning a
list of pairs to a hash, because separators altinate with separated fields, It
users parentheses to return part of each separator as part of the returned list
value. Since the split pattern is guaranteed to return things in pairs by virtue
of containing one set of parentheses, the hash assignment is guaranteed to
receive a list consisting of key/value pairs, where each key is the name of a
header field. (Unfortunately, this technique loses information for multiple lines
with the same key field, such as Received-By lines. Ah well)

$header =~ s/\n\s+/ /g; # Merge continuation lines.
%head = ("FRONTSTUFF", Esjis::split(/^(\S*?):\s*/m, $header));

The following example processes the entries in a Unix passwd(5) file. You could
leave out the chomp, in which case $shell would have a newline on the end of it.

open(PASSWD, "/etc/passwd");
while (<PASSWD>) {
    chomp; # remove trailing newline.
    ($login, $passwd, $uid, $gid, $gcos, $home, $shell) =
        Esjis::split(/:/);
    ...
}

Here's how process each word of each line of each file of input to create a
word-frequency hash.

while (<>) {
    for my $word (Esjis::split()) {
        $count{$word}++;
    }
}

The inverse of Esjis::split is join, except that join can only join with the
same separator between all fields. To break apart a string with fixed-position
fields, use unpack.

Processing long $string (over 32766 octets) requires Perl 5.010001 or later.

Transliteration

$tr = Esjis::tr($variable,$bind_operator,$searchlist,$replacementlist,$modifier);
$tr = Esjis::tr($variable,$bind_operator,$searchlist,$replacementlist);

This is the transliteration (sometimes erroneously called translation) operator,
which is like the y/// operator in the Unix sed program, only better, in
everybody's humble opinion.

This subroutine scans a ShiftJIS string character by character and replaces all
occurrences of the characters found in $searchlist with the corresponding character
in $replacementlist. It returns the number of characters replaced or deleted.
If no ShiftJIS string is specified via =~ operator, the $_ variable is translated.
$modifier are:

---------------------------------------------------------------------------
Modifier   Meaning
---------------------------------------------------------------------------
c          Complement $searchlist.
d          Delete found but unreplaced characters.
s          Squash duplicate replaced characters.
r          Return transliteration and leave the original string untouched.
---------------------------------------------------------------------------

To use with a read-only value without raising an exception, use the /r modifier.

print Esjis::tr('bookkeeper','=~','boep','peob','r'); # prints 'peekkoobor'

Chop string

$chop = Esjis::chop(@list);
$chop = Esjis::chop();
$chop = Esjis::chop;

This subroutine chops off the last character of a string variable and returns the
character chopped. The Esjis::chop subroutine is used primary to remove the newline
from the end of an input recoed, and it is more efficient than using a
substitution. If that's all you're doing, then it would be safer to use chomp,
since Esjis::chop always shortens the string no matter what's there, and chomp
is more selective. If no argument is given, the subroutine chops the $_ variable.

You cannot Esjis::chop a literal, only a variable. If you Esjis::chop a list of
variables, each string in the list is chopped:

@lines = `cat myfile`;
Esjis::chop(@lines);

You can Esjis::chop anything that is an lvalue, including an assignment:

Esjis::chop($cwd = `pwd`);
Esjis::chop($answer = <STDIN>);

This is different from:

$answer = Esjis::chop($tmp = <STDIN>); # WRONG

which puts a newline into $answer because Esjis::chop returns the character
chopped, not the remaining string (which is in $tmp). One way to get the result
intended here is with substr:

$answer = substr <STDIN>, 0, -1;

But this is more commonly written as:

Esjis::chop($answer = <STDIN>);

In the most general case, Esjis::chop can be expressed using substr:

$last_code = Esjis::chop($var);
$last_code = substr($var, -1, 1, ""); # same thing

Once you understand this equivalence, you can use it to do bigger chops. To
Esjis::chop more than one character, use substr as an lvalue, assigning a null
string. The following removes the last five characters of $caravan:

substr($caravan, -5) = '';

The negative subscript causes substr to count from the end of the string instead
of the beginning. To save the removed characters, you could use the four-argument
form of substr, creating something of a quintuple Esjis::chop;

$tail = substr($caravan, -5, 5, '');

This is all dangerous business dealing with characters instead of graphemes. Perl
doesn't really have a grapheme mode, so you have to deal with them yourself.

Index string

$byte_pos = Esjis::index($string,$substr,$byte_offset);
$byte_pos = Esjis::index($string,$substr);

This subroutine searches for one string within another. It returns the byte position
of the first occurrence of $substring in $string. The $byte_offset, if specified,
says how many bytes from the start to skip before beginning to look. Positions are
based at 0. If the substring is not found, the subroutine returns one less than the
base, ordinarily -1. To work your way through a string, you might say:

$byte_pos = -1;
while (($byte_pos = Esjis::index($string, $lookfor, $byte_pos)) > -1) {
    print "Found at $byte_pos\n";
    $byte_pos++;
}

Reverse index string

$byte_pos = Esjis::rindex($string,$substr,$byte_offset);
$byte_pos = Esjis::rindex($string,$substr);

This subroutine works just like Esjis::index except that it returns the byte
position of the last occurrence of $substring in $string (a reverse Esjis::index).
The subroutine returns -1 if $substring is not found. $byte_offset, if specified,
is the rightmost byte position that may be returned. To work your way through a
string backward, say:

$byte_pos = length($string);
while (($byte_pos = Sjis::rindex($string, $lookfor, $byte_pos)) >= 0) {
    print "Found at $byte_pos\n";
    $byte_pos--;
}

Lower case string

$lc = Esjis::lc($string);
$lc = Esjis::lc_;

This subroutine returns a lowercased version of ShiftJIS $string (or $_, if
$string is omitted). This is the internal subroutine implementing the \L escape
in double-quoted strings.

You can use the Esjis::fc subroutine for case-insensitive comparisons via Sjis
software.

Lower case first character of string

$lcfirst = Esjis::lcfirst($string);
$lcfirst = Esjis::lcfirst_;

This subroutine returns a version of ShiftJIS $string with the first character
lowercased (or $_, if $string is omitted). This is the internal subroutine
implementing the \l escape in double-quoted strings.

Upper case string

$uc = Esjis::uc($string);
$uc = Esjis::uc_;

This subroutine returns an uppercased version of ShiftJIS $string (or $_, if
$string is omitted). This is the internal subroutine implementing the \U escape
in interpolated strings. For titlecase, use Esjis::ucfirst instead.

You can use the Esjis::fc subroutine for case-insensitive comparisons via Sjis
software.

Upper case first character of string

$ucfirst = Esjis::ucfirst($string);
$ucfirst = Esjis::ucfirst_;

This subroutine returns a version of ShiftJIS $string with the first character
titlecased and other characters left alone (or $_, if $string is omitted).
Titlecase is "Camel" for an initial capital that has (or expects to have)
lowercase characters following it, not uppercase ones. Exsamples are the first
letter of a sentence, of a person's name, of a newspaper headline, or of most
words in a title. Characters with no titlecase mapping return the uppercase
mapping instead. This is the internal subroutine implementing the \u escape in
double-quoted strings.

To capitalize a string by mapping its first character to titlecase and the rest
to lowercase, use:

$titlecase = Esjis::ucfirst(substr($word,0,1)) . Esjis::lc(substr($word,1));

or

$string =~ s/(\w)(\w*)/\u$1\L$2/g;

Do not use:

$do_not_use = Esjis::ucfirst(Esjis::lc($word));

or "\u\L$word", because that can produce a different and incorrect answer with
certain characters. The titlecase of something that's been lowercased doesn't
always produce the same thing titlecasing the original produces.

Because titlecasing only makes sense at the start of a string that's followed
by lowercase characters, we can't think of any reason you might want to titlecase
every character in a string.

See also P.287 A Case of Mistaken Identity
in Chapter 6: Unicode
of ISBN 978-0-596-00492-7 Programming Perl 4th Edition.

Fold case string

P.860 fc
in Chapter 27: Functions
of ISBN 978-0-596-00492-7 Programming Perl 4th Edition.

$fc = Esjis::fc($string);
$fc = Esjis::fc_;

New to Sjis software, this subroutine returns the full Unicode-like casefold of
ShiftJIS $string (or $_, if omitted). This is the internal subroutine implementing
the \F escape in double-quoted strings.

Just as title-case is based on uppercase but different, foldcase is based on
lowercase but different. In ASCII there is a one-to-one mapping between only
two cases, but in other encoding there is a one-to-many mapping and between three
cases. Because that's too many combinations to check manually each time, a fourth
casemap called foldcase was invented as a common intermediary for the other three.
It is not a case itself, but it is a casemap.

To compare whether two strings are the same without regard to case, do this:

Esjis::fc($a) eq Esjis::fc($b)

The reliable way to compare string case-insensitively was with the /i pattern
modifier, because Sjis software has always used casefolding semantics for
case-insensitive pattern matches. Knowing this, you can emulate equality
comparisons like this:

sub fc_eq ($$) {
    my($a,$b) = @_;
    return $a =~ /\A\Q$b\E\z/i;
}

Make ignore case string

@ignorecase = Esjis::ignorecase(@string);

This subroutine is internal use to m/ /i, s/ / /i, split / /i, and qr/ /i.

Make capture number

$capturenumber = Esjis::capture($string);

This subroutine is internal use to m/ /, s/ / /, split / /, and qr/ /.

Make character

$chr = Esjis::chr($code);
$chr = Esjis::chr_;

This subroutine returns a programmer-visible character, character represented by
that $code in the character set. For example, Esjis::chr(65) is "A" in either
ASCII or ShiftJIS, not Unicode. For the reverse of Esjis::chr, use Sjis::ord.

File test subroutine Esjis::X

The following all subroutines function when the pathname ends with chr(0x5C) on
MSWin32.

A file test subroutine is a unary function that takes one argument, either a
filename or a filehandle, and tests the associated file to see whether something
is true about it. If the argument is omitted, it tests $_. Unless otherwise
documented, it returns 1 for true and "" for false, or the undefined value if
the file doesn't exist or is otherwise inaccessible. Currently implemented file
test subroutines are listed in:

Available in MSWin32, MacOS, and UNIX-like systems
------------------------------------------------------------------------------
Subroutine and Prototype   Meaning
------------------------------------------------------------------------------
Esjis::r(*), Esjis::r_()   File or directory is readable by this (effective) user or group
Esjis::w(*), Esjis::w_()   File or directory is writable by this (effective) user or group
Esjis::e(*), Esjis::e_()   File or directory name exists
Esjis::x(*), Esjis::x_()   File or directory is executable by this (effective) user or group
Esjis::z(*), Esjis::z_()   File exists and has zero size (always false for directories)
Esjis::f(*), Esjis::f_()   Entry is a plain file
Esjis::d(*), Esjis::d_()   Entry is a directory
------------------------------------------------------------------------------

Available in MacOS and UNIX-like systems
------------------------------------------------------------------------------
Subroutine and Prototype   Meaning
------------------------------------------------------------------------------
Esjis::R(*), Esjis::R_()   File or directory is readable by this real user or group
                           Same as Esjis::r(*), Esjis::r_() on MacOS
Esjis::W(*), Esjis::W_()   File or directory is writable by this real user or group
                           Same as Esjis::w(*), Esjis::w_() on MacOS
Esjis::X(*), Esjis::X_()   File or directory is executable by this real user or group
                           Same as Esjis::x(*), Esjis::x_() on MacOS
Esjis::l(*), Esjis::l_()   Entry is a symbolic link
Esjis::S(*), Esjis::S_()   Entry is a socket
------------------------------------------------------------------------------

Not available in MSWin32 and MacOS
------------------------------------------------------------------------------
Subroutine and Prototype   Meaning
------------------------------------------------------------------------------
Esjis::o(*), Esjis::o_()   File or directory is owned by this (effective) user
Esjis::O(*), Esjis::O_()   File or directory is owned by this real user
Esjis::p(*), Esjis::p_()   Entry is a named pipe (a "fifo")
Esjis::b(*), Esjis::b_()   Entry is a block-special file (like a mountable disk)
Esjis::c(*), Esjis::c_()   Entry is a character-special file (like an I/O device)
Esjis::u(*), Esjis::u_()   File or directory is setuid
Esjis::g(*), Esjis::g_()   File or directory is setgid
Esjis::k(*), Esjis::k_()   File or directory has the sticky bit set
------------------------------------------------------------------------------

The tests -T and -B takes a try at telling whether a file is text or binary.
But people who know a lot about filesystems know that there's no bit (at least
in UNIX-like operating systems) to indicate that a file is a binary or text file
--- so how can Perl tell?
The answer is that Perl cheats. As you might guess, it sometimes guesses wrong.

This incomplete thinking of file test operator -T and -B gave birth to UTF8 flag
of a later period.

The Esjis::T, Esjis::T_, Esjis::B, and Esjis::B_ work as follows. The first block
or so of the file is examined for strange chatracters such as
[\000-\007\013\016-\032\034-\037\377] (that don't look like ShiftJIS). If more
than 10% of the bytes appear to be strange, it's a *maybe* binary file;
otherwise, it's a *maybe* text file. Also, any file containing ASCII NUL(\0) or
\377 in the first block is considered a binary file. If Esjis::T or Esjis::B is
used on a filehandle, the current input (standard I/O or "stdio") buffer is
examined rather than the first block of the file. Both Esjis::T and Esjis::B
return 1 as true on an empty file, or on a file at EOF (end-of-file) when testing
a filehandle. Both Esjis::T and Esjis::B doesn't work when given the special
filehandle consisting of a solitary underline. Because Esjis::T has to read to
do the test, you don't want to use Esjis::T on special files that might hang or
give you other kinds or grief. So on most occasions you'll want to test with a
Esjis::f first, as in:

next unless Esjis::f($file) && Esjis::T($file);

Available in MSWin32, MacOS, and UNIX-like systems
------------------------------------------------------------------------------
Subroutine and Prototype   Meaning
------------------------------------------------------------------------------
Esjis::T(*), Esjis::T_()   File looks like a "text" file
Esjis::B(*), Esjis::B_()   File looks like a "binary" file
------------------------------------------------------------------------------

File ages for Esjis::M, Esjis::M_, Esjis::A, Esjis::A_, Esjis::C, and Esjis::C_
are returned in days (including fractional days) since the script started running.
This start time is stored in the special variable $^T ($BASETIME). Thus, if the
file changed after the script, you would get a negative time. Note that most time
values (86,399 out of 86,400, on average) are fractional, so testing for equality
with an integer without using the int function is usually futile. Examples:

next unless Esjis::M($file) > 0.5;     # files are older than 12 hours
&newfile if Esjis::M($file) < 0;       # file is newer than process
&mailwarning if int(Esjis::A_) == 90;  # file ($_) was accessed 90 days ago today

Available in MSWin32, MacOS, and UNIX-like systems
------------------------------------------------------------------------------
Subroutine and Prototype   Meaning
------------------------------------------------------------------------------
Esjis::M(*), Esjis::M_()   Modification age (measured in days)
Esjis::A(*), Esjis::A_()   Access age (measured in days)
                           Same as Esjis::M(*), Esjis::M_() on MacOS
Esjis::C(*), Esjis::C_()   Inode-modification age (measured in days)
------------------------------------------------------------------------------

The Esjis::s, and Esjis::s_ returns file size in bytes if succesful, or undef
unless successful.

Available in MSWin32, MacOS, and UNIX-like systems
------------------------------------------------------------------------------
Subroutine and Prototype   Meaning
------------------------------------------------------------------------------
Esjis::s(*), Esjis::s_()   File or directory exists and has nonzero size
                           (the value is the size in bytes)
------------------------------------------------------------------------------

Filename expansion (globbing)

@glob = Esjis::glob($string);
@glob = Esjis::glob_;

This subroutine returns the value of $string with filename expansions the way a
DOS-like shell would expand them, returning the next successive name on each
call. If $string is omitted, $_ is globbed instead. This is the internal
subroutine implementing the <*> and glob operator.
This subroutine function when the pathname ends with chr(0x5C) on MSWin32.

For ease of use, the algorithm matches the DOS-like shell's style of expansion,
not the UNIX-like shell's. An asterisk ("*") matches any sequence of any
character (including none). A question mark ("?") matches any one character or
none. A tilde ("~") expands to a home directory, as in "~/.*rc" for all the
current user's "rc" files, or "~jane/Mail/*" for all of Jane's mail files.

Note that all path components are case-insensitive, and that backslashes and
forward slashes are both accepted, and preserved. You may have to double the
backslashes if you are putting them in literally, due to double-quotish parsing
of the pattern by perl.

The Esjis::glob subroutine grandfathers the use of whitespace to separate multiple
patterns such as <*.c *.h>. If you want to glob filenames that might contain
whitespace, you'll have to use extra quotes around the spacy filename to protect
it. For example, to glob filenames that have an "e" followed by a space followed
by an "f", use either of:

@spacies = <"*e f*">;
@spacies = Esjis::glob('"*e f*"');
@spacies = Esjis::glob(q("*e f*"));

If you had to get a variable through, you could do this:

@spacies = Esjis::glob("'*${var}e f*'");
@spacies = Esjis::glob(qq("*${var}e f*"));

Another way on MSWin32

# relative path
@relpath_file = split(/\n/,`dir /b wildcard\\here*.txt 2>NUL`);

# absolute path
@abspath_file = split(/\n/,`dir /s /b wildcard\\here*.txt 2>NUL`);

# on COMMAND.COM
@relpath_file = split(/\n/,`dir /b wildcard\\here*.txt`);
@abspath_file = split(/\n/,`dir /s /b wildcard\\here*.txt`);

Statistics about link

@lstat = Esjis::lstat($file);
@lstat = Esjis::lstat_;

Like Esjis::stat, returns information on file, except that if file is a symbolic
link, Esjis::lstat returns information about the link; Esjis::stat returns
information about the file pointed to by the link. If symbolic links are
unimplemented on your system, a normal Esjis::stat is done instead. If file is
omitted, returns information on file given in $_. Returns values (especially
device and inode) may be bogus.
This subroutine function when the filename ends with chr(0x5C) on MSWin32.

Open directory handle

$rc = Esjis::opendir(DIR,$dir);

This subroutine opens a directory named $dir for processing by readdir, telldir,
seekdir, rewinddir, and closedir. The subroutine returns true if successful.
Directory handles have their own namespace from filehandles.
This subroutine function when the directory name ends with chr(0x5C) on MSWin32.

Statistics about file

$stat = Esjis::stat(FILEHANDLE);
$stat = Esjis::stat(DIRHANDLE);
$stat = Esjis::stat($expr);
$stat = Esjis::stat_;
@stat = Esjis::stat(FILEHANDLE);
@stat = Esjis::stat(DIRHANDLE);
@stat = Esjis::stat($expr);
@stat = Esjis::stat_;

In scalar context, this subroutine returns a Boolean value that indicates whether
the call succeeded. In list context, it returns a 13-element list giving the
statistics for a file, either the file opened via FILEHANDLE or DIRHANDLE, or
named by $expr. It's typically used as followes:

($dev,$ino,$mode,$nlink,$uid,$gid,$rdev,$size,
    $atime,$mtime,$ctime,$blksize,$blocks) = Esjis::stat($expr);

Not all fields are supported on all filesystem types; unsupported fields return
0. Here are the meanings of the fields:

-------------------------------------------------------------------------
Index  Field      Meaning
-------------------------------------------------------------------------
  0    $dev       Device number of filesystem
                  drive number for MSWin32
                  vRefnum for MacOS
  1    $ino       Inode number
                  zero for MSWin32
                  fileID/dirID for MacOS
  2    $mode      File mode (type and permissions)
  3    $nlink     Nunmer of (hard) links to the file
                  usually one for MSWin32 --- NTFS filesystems may
                  have a value greater than one
                  1 for MacOS
  4    $uid       Numeric user ID of file's owner
                  zero for MSWin32
                  zero for MacOS
  5    $gid       Numeric group ID of file's owner
                  zero for MSWin32
                  zero for MacOS
  6    $rdev      The device identifier (special files only)
                  drive number for MSWin32
                  NULL for MacOS
  7    $size      Total size of file, in bytes
  8    $atime     Last access time since the epoch
                  same as $mtime for MacOS
  9    $mtime     Last modification time since the epoch
                  since 1904-01-01 00:00:00 for MacOS
 10    $ctime     Inode change time (not creation time!) since the epoch
                  creation time instead of inode change time for MSWin32
                  since 1904-01-01 00:00:00 for MacOS
 11    $blksize   Preferred blocksize for file system I/O
                  zero for MSWin32
 12    $blocks    Actual number of blocks allocated
                  zero for MSWin32
                  int(($size + $blksize-1) / $blksize) for MacOS
-------------------------------------------------------------------------

$dev and $ino, token together, uniquely identify a file on the same system.
The $blksize and $blocks are likely defined only on BSD-derived filesystems.
The $blocks field (if defined) is reported in 512-byte blocks. The value of
$blocks * 512 can differ greatly from $size for files containing unallocated
blocks, or "hole", which aren't counted in $blocks.

If Esjis::stat is passed the special filehandle consisting of an underline, no
actual stat(2) is done, but the current contents of the stat structure from
the last Esjis::stat, Esjis::lstat, or Esjis::stat-based file test subroutine
(such as Esjis::r, Esjis::w, and Esjis::x) are returned.

Because the mode contains both the file type and its permissions, you should
mask off the file type portion and printf or sprintf using a "%o" if you want
to see the real permissions:

$mode = (Esjis::stat($expr))[2];
printf "Permissions are %04o\n", $mode & 07777;

If $expr is omitted, returns information on file given in $_.
This subroutine function when the filename ends with chr(0x5C) on MSWin32.

Deletes a list of files.

$unlink = Esjis::unlink(@list);
$unlink = Esjis::unlink($file);
$unlink = Esjis::unlink;

Delete a list of files. (Under Unix, it will remove a link to a file, but the
file may still exist if another link references it.) If list is omitted, it
unlinks the file given in $_. The subroutine returns the number of files
successfully deleted.
This subroutine function when the filename ends with chr(0x5C) on MSWin32.

Changes the working directory.

$chdir = Esjis::chdir($dirname);
$chdir = Esjis::chdir;

This subroutine changes the current process's working directory to $dirname, if
possible. If $dirname is omitted, $ENV{'HOME'} is used if set, and $ENV{'LOGDIR'}
otherwise; these are usually the process's home directory. The subroutine returns
true on success, false otherwise (and puts the error code into $!).

chdir("$prefix/lib") || die "Can't cd to $prefix/lib: $!";

This subroutine has limitation on the MSWin32. See also BUGS AND LIMITATIONS.

Do file

$return = Esjis::do($file);

The do FILE form uses the value of FILE as a filename and executes the contents
of the file as a Perl script. Its primary use is (or rather was) to include
subroutines from a Perl subroutine library, so that:

Esjis::do('stat.pl');

is rather like: 

scalar eval `cat stat.pl`;   # `type stat.pl` on Windows

except that Esjis::do is more efficient, more concise, keeps track of the current
filename for error messages, searches all the directories listed in the @INC
array, and updates %INC if the file is found.
It also differs in that code evaluated with Esjis::do FILE can not see lexicals in
the enclosing scope, whereas code in eval FILE does. It's the same, however, in
that it reparses the file every time you call it -- so you might not want to do
this inside a loop unless the filename itself changes at each loop iteration.

If Esjis::do can't read the file, it returns undef and sets $! to the error. If 
Esjis::do can read the file but can't compile it, it returns undef and sets an
error message in $@. If the file is successfully compiled, do returns the value of
the last expression evaluated.

Inclusion of library modules (which have a mandatory .pm suffix) is better done
with the use and require operators, which also Esjis::do error checking and raise
an exception if there's a problem. They also offer other benefits: they avoid
duplicate loading, help with object-oriented programming, and provide hints to the
compiler on function prototypes.

But Esjis::do FILE is still useful for such things as reading program configuration
files. Manual error checking can be done this way:

# read in config files: system first, then user
for $file ("/usr/share/proggie/defaults.rc", "$ENV{HOME}/.someprogrc") {
    unless ($return = Esjis::do($file)) {
        warn "couldn't parse $file: $@" if $@;
        warn "couldn't Esjis::do($file): $!" unless defined $return;
        warn "couldn't run $file"            unless $return;
    }
}

A long-running daemon could periodically examine the timestamp on its configuration
file, and if the file has changed since it was last read in, the daemon could use
Esjis::do to reload that file. This is more tidily accomplished with Esjis::do than
with Esjis::require.

Require file

Esjis::require($file);
Esjis::require();

This subroutine asserts a dependency of some kind on its argument. If an argument is
not supplied, $_ is used.

Esjis::require loads and executes the Perl code found in the separate file whose
name is given by the $file. This is similar to using a Esjis::do on a file, except
that Esjis::require checks to see whether the library file has been loaded already
and raises an exception if any difficulties are encountered. (It can thus be used
to express file dependencies without worrying about duplicate compilation.) Like
its cousins Esjis::do, Esjis::require knows how to search the include path stored
in the @INC array and to update %INC on success.

The file must return true as the last value to indicate successful execution of any
initialization code, so it's customary to end such a file with 1 unless you're sure
it'll return true otherwise.

Current position of the readdir

$telldir = Esjis::telldir(DIRHANDLE);

This subroutine returns the current position of the readdir routines on DIRHANDLE.
This value may be given to seekdir to access a particular location in a directory.
The subroutine has the same caveats about possible directory compaction as the
corresponding system library routine. This subroutine might not be implemented
everywhere that readdir is. Even if it is, no calculation may be done with the
return value. It's just an opaque value, meaningful only to seekdir.