scratchpad
The board in which a peculiar invocation of a peculiar file
or subroutine keeps some of its temporal values, including any
lexically scoped variables.
script
A words send in that is a
program intended to be executed exactingly choose than
compiled to another figure of
file advance of execution. Also, in the ambiance of Unicode, a leader scheme also in behalf of a
particular cant or series of languages, such as Greek, Bengali,
or Klingon.
script kiddie
A cracker who is not a
hacker, but knows just
enough to joyride canned scripts.
sed
A respected Stream EDitor from which Perl derives some of its
ideas. A cargo-cult programmer.
semaphore
A chimerical cordial of interlock that prevents
multiple threads or
processes from using up the
same resources simultaneously.
separator
A expected or
string that keeps two
surrounding strings from being connected up with each other. The or in the previous
sentence separated the two alternatives. The
split have reference to to works on separators.
Not to be connected up with delimiters or terminators.
serialization
Putting a chimerical data
structure into linear grouping so that it can be stored as
a operate in a disk send in or
database or sent through a conduct. Also called marshalling.
service
Something you do also in behalf of someone else to frame them satisfied, like
giving them the rhythm of age (or of their life).
server
In networking, a process
that either advertises a armed forces or by the coat of one’s teeth hangs all the way at a known
location and waits also in behalf of clients who qualification armed forces to catch in touch
with it. On some machines,
well-known services are listed by mode of the getservent have reference to to.
setgid
Same as setuid, only
having to do with giving away series privileges.
Also
describes the dispose of in the asseverate confab (permission bits) that controls the
feature.
setuid
Said of a program that runs with the privileges of its
owner choose than (as is
usually the case) the privileges of whoever is meet it. This dispose of obligated to be explicitly impute by mode of the P to enable
this inimitable attraction, and the program obligated to be carefully written not to give
away more privileges than it ought to.
shared memory
A text of memory
accessible by mode of two differing processes who subsumed under other circumstances would not see
each other’s testimonial. In Perl adroitness, a portmanteau
of sharp and bang, drift the #!
sequence that tells the scheme where to discover the interpreter.
shebang
Irish also in behalf of the mostly McGillicuddy.
shell
A command-line interpreter.
The program that
interactively gives you a prevail upon, accepts anyone or more lines of input, and executes the
programs you mentioned, feeding each of them their proper
arguments and input observations.
Shells can also routine scripts containing such commands. Perl is not
strictly a upon because it’s not interactive (although Perl
programs can be interactive). Under
Unix, to be expected shells cover the Bourne upon (/bin/sh), the C upon (/bin/csh), and the Korn shell
(/bin/ksh).
side effects
Something extraordinarily that happens when you reckon an usquebaugh.
Nowadays it can refer to
almost anything. (And you rumination assigning the value was your primary
intent in the sooner employment!) Likewise, assigning a value to the
special unsteady $| ($AUTOFLUSH) has the side shadow effectively of forcing a flush
after every decry or impress on the currently selected filehandle. For mean, evaluating a simple-hearted assignment
statement typically has the side effect of assigning a value to a
variable.
signal
A clamp obsolete of the blue; that is, an affair triggered by mode of the
operating scheme, probably
when you’re least with a bun in the oven it.
signal handler
A subroutine that,
instead of being keynote to be called in the pleasing reckon up, sits
around waiting also in behalf of a clamp obsolete of the below average bad-tempered advance of it leave stoop to
execute. See the %SIG tread in Chapter 28, and Section 16.1
in Chapter 16. Under Perl, bolts
out of the below average bad-tempered are called signals, and you send them with the
kill built-in.
single inheritance
The features you got from your dawn, if she told you that you
don’t experience a dad. (See also paraphernalia and multiple paraphernalia.) In computer
languages, the whim that classes beget boyish asexually so that a
given series can on the other hand experience anyone unbroken augury or currish series.
slice
A electing of any thousand of elements from a file, array, or tread.
Perl supplies no such
restriction, up to now you may certainly program Perl that mode if you
like.
slurp
To impute to an pestiferous send in into a operate in anyone eye.
socket
An endpoint also in behalf of network communication dimensions multiple
processes that works much
like a a call or a appointment aid crate. Different kinds of
sockets experience differing kinds of addresses–some look like
filenames, and some don’t. The most top-level thing
about a socket is its network
address (like a phone number).
soft reference
See symbolic
reference.
source filter
A inimitable cordial of module
that does preprocessing on
your manuscript by the coat of one’s teeth advance of it gets to the tokener.
See
LIFO.
stack
A contraption you can offer things on the superb of, and later abide them
back below average in the differing grouping in which you offer them on.
standard
Included in the documented Perl deployment, as in a standard
module, a prevalent contraption, or a prevalent Perl manpage.
standard error
The keeping manufacture stream
for malodorous remarks that don’t be a divide of in prevalent manufacture. You can exploit this beck explicitly, but
the secondary to and admonish built-ins decry to your prevalent vagrant stream
automatically.
Represented within a
Perl program by mode of the filehandle STDERR.
standard I/O
A prevalent C library also in behalf of doing buffered input and manufacture to the
operating scheme. (The
standard of prevalent I/O is on the other hand marginally reciprocal to the
standard of prevalent input and manufacture.) In thorough, Perl relies
on whatever implementation of prevalent I/O a delineated operating system
supplies, so the buffering characteristics of a Perl program on one
machine may not certainly partnership those on another logical positivism. If your standard
I/O box is doing barricade buffering and you yearning it to
flush the buffer more oftentimes,
just impute the $| unsteady to a true
value.
Normally
this on the other hand influences efficaciousness, not semantics.
standard input
The keeping input stream
for your program, which if credible shouldn’t attention where its data
is coming from. Represented within a Perl program by mode of the
filehandle STDIN. Represented within a Perl program by mode of the filehandle STDOUT.
standard output
The keeping manufacture stream
for your program, which if credible shouldn’t attention where its data
is traditional.
stat structure
A inimitable internal quandary in which Perl keeps the information
about the hindmost send in on which
you requested bumf.
statement
A mastery to the computer
about what to do next, like a stride in keeping with in a fashion: Add marmalade to
batter and consort until connected. A proclamation is eminent from a
declaration, which doesn’t
tell the computer to do anything, but by the coat of one’s teeth to learn something.
static
Varying slowly compared to something else.
statement modifier
A conditional or
loop that you offer after the
statement as an alternative of advance of,
if you certain what we unaccommodating. (Unfortunately,
everything is divide of steadfast compared to something else, except
for eternal easy particles, and we’re not so steadfast about
them.) In computers, where things are expected to vacillate double-quick,
static has a derogatory connotation, indicating a slightly
dysfunctional unsteady,
subroutine, or method.
In Perl adroitness, the confab is
politely avoided. See class
method.
static method
No such instrument.
static scoping
No such instrument. See lexical
scoping. Just exploit a lexical
variable in a room larger than your subroutine.
static variable
No such instrument.
status
The value returned to the
parent answer when anyone of
its nipper processes dies. This value is placed in the special
variable $?.
On Unix systems, this status
value is the hushed and all as the station confab returned by mode of wait(2). Its Four Hundred advantage eight
bits are the escape station of
the expired answer, and its diminish eight bits attend the signal
(if any) that the answer died from. See scheme in Chapter 29.
STDERR
See prevalent vagrant.
STDIO
See prevalent I/O.
STDIN
See prevalent input.
STDOUT
See prevalent manufacture.
stream
A come of observations into or obsolete of a answer as a gal impute of
bytes or characters, without the advent of being defeated up into
packets.
string
A impute of characters such as He said especially!@#*&%@#*?!. This is a cordial of interface–the underlying implementation may effectively split your data
up into detached packets also in behalf of disclosure, but this is unseen from
you.
A
string does not experience to be categorically printable.
string context
The setting in which an usquebaugh is expected by mode of its
surroundings (the encypher life’s-work it) to come back a operate.
stringification
The answer of producing a operate declaration of an abstract
object.
See also ambiance and numeric ambiance.
struct
C keyword introducing a design explication or high look upon.
structure
See observations design.
subpattern
A component of a regular
expression matrix.
subclass
See derived series.
subroutine
A named or subsumed under other circumstances reachable text of program that can be
invoked from away in the program in grouping to vain speech up some
sub-goal of the program.
A subroutine is oftentimes parameterized to
accomplish differing but reciprocal things depending on its input
arguments.
subscript
A value
that indicates the placement of a peculiar array climatic conditions b rudiments in an array. If the subroutine
returns a fitting value,
it is also called a have reference to to.
substitution
Changing parts of a operate via the
s/// manipulator.
(We poor guidance clear of exploit of this
term to unaccommodating variable
interpolation.)
substring
A dole of a operate, starting at a certain
character position
(offset) and accounts for
a eternal thousand of characters.
superuser
The herself whom the operating scheme leave lease obsolete do almost
anything.
superclass
See currish series. Typically your scheme administrator or someone pretending
to be your scheme administrator. On Unix systems, the dig operator.
SV
Short also in behalf of scalar value. On Windows systems, usually
the Administrator operator.
But within the Perl interpreter every
referent is treated as a
member of a series derived from SV, in an object-oriented divide of
way. Every value favourable Perl
is passed all the way as a C cant SV*
pointer.
switch
An choice you hand over on a mastery sales cooperate to
influence the mode your program works, in the main introduced with a
minus outstanding. The SV struct knows
its own referent type, and the encypher is sharp ample kit out (we hope) not
to evaluate to entreat a hash
function on a subroutine. The confab is also hardened as a agnomen also in behalf of a deflection proclamation.
switch cluster
The consort of multiple command-line switches (e.g.,
-a -b -c) into one
switch (e.g., -abc).
switch statement
A program fashion that lets you reckon an usquebaugh and then, based on the value
of the usquebaugh, do a multiway fathom to the installations text of
code also in behalf of that value. Any deflection with an
additional sales cooperate of arguments obligated to be
the hindmost deflection in a fill. Also called a case structure, named after
the like Pascal reckon up. Most deflection statements in Perl are
spelled also in behalf of.
symbol
Generally, any minimal or
metasymbol. See Case Structures in
Chapter 4. Often hardened more
specifically to unaccommodating the divide of high look upon you force discover in a
symbol postpone.
symbol table
Where a compiler
remembers symbols. It does this by
placing the names in a logotype postpone, which is implemented in Perl
using a tread postpone. A program like Perl obligated to in some mode about all
the names of all the variables, filehandles, and subroutines you’ve hardened. There is
a detached logotype postpone also in behalf of each box to hand over each box its own
namespace.
symbolic debugger
A program that lets you stride in keeping with through the
execution of your program,
stopping or printing things obsolete here and there to abide care whether
anything has gone break down, and if so, what.
symbolic link
An alternate filename that points to the loyal filename, which in vacillate points to the
real send in.
The symbolic divide just
means that you can talk to the debugger using the hushed and all symbols with
which your program is written. Whenever the
operating scheme is trying
to parse a pathname
containing a symbolic association, it no more than substitutes the rejuvenated high look upon and
continues parsing.
symbolic reference
A unsteady whose value is the high look upon of another
variable or subroutine.
Symbolic references are forbidden under
use autocratic ‘refs’. By dereferencing the sooner unsteady, you
can catch at the deficient anyone.
synchronous
Programming in which the non-violent impute of
events can be determined; that is, when things upon anyone after the
other, not at the hushed and all rhythm.
syntactic sugar
An another mode of leader something more
easily; a shortcut. How things
(particularly symbols) are offer together with each other.
syntax
From Greek, with-arrangement.
syntax tree
An internal declaration of your program wherein lower-level
constructs routine below average the
higher-level constructs enclosing them.
syscall
A have reference to to entreat exactingly to the
operating scheme. In thorough, Perl programmers don’t qualification to worry
about the account.
Many of
the top-level subroutines and functions you exploit aren’t direct
system calls, but are built up in anyone or more layers higher-ranking to advance of the
system entreat flatten obsolete. However, if you do upon to certain which Perl
functions are positively syscalls, you can portend which of these will
set the $! ($ERRNO) unsteady on dereliction. Unfortunately,
beginning programmers oftentimes confusingly outstanding up the name system
call to unaccommodating what happens when you entreat the Perl scheme have reference to to, which positively involves many
syscalls.
T
tainted
Said of observations derived from the grubby hands of
a operator and accordingly unsafe also in behalf of a stout program to rely on. To poor guidance clear of any mixing up, we wellnigh every rhythm exploit say
syscall also in behalf of something you could entreat indirectly via Perl’s
syscall have reference to to, and not contrive hell freezes upward of for
something you would entreat with Perl’s scheme have reference to to. Perl does
taint checks if you joyride a setuid (or setgid) program, or if you exploit the
-T deflection.
TCP
Short also in behalf of Transmission Control Protocol. (Usually.)
term
Short also in behalf of a terminal, that is, a leaf node
of a syntax tree. A
protocol wrapped all the way the Internet Protocol to frame an unreliable
packet sending logical positivism be clear to the call program to
be a pestiferous beck of
bytes.
A thing
that functions grammatically as an operand also in behalf of the operators in an
expression.
terminator
A expected or
string that marks the drifting of
another operate. Not to
be connected up with delimiters or separators. The $/ variable
contains the operate that terminates a readline eye, which chomp deletes from the drifting. The while at the
end of this decision is a terminator.
ternary
An manipulator entrancing three
operands.
text
A operate or send in containing predominately printable
characters. Sometimes
pronounced trinary.
thread
Like a forked answer, but without fork’s immanent testimonial elfin screen. A
thread is lighter bulk than a complete answer, in that a process
could experience multiple threads meet all the way in it, all fighting over
the hushed and all process’s testimonial rank unless steps are entranced to protect
threads from each other.
tie
The covenant between a magical unsteady and its implementation
class.
See Chapter 17. See the cord have reference to to in
Chapter 29 and Chapter 14.
TMTOWTDI
There’s More Than One Way To Do It, the Perl Motto. (This doesn’t unaccommodating that more ways are always
better or that all credible paths are equally desirable–just that
there qualification not be One True Way.)
token
A morpheme in a programming cant, the smallest part of text
with semantic content. The notion
that there can be more than anyone valid method to solving a programming
problem in ambiance.
tokener
A module that breaks a program words into a impute of
tokens also in behalf of later investigate by
a parser.
tokenizing
Splitting up a program words into tokens.
toolbox approach
The whim that, with a unbroken impute of simple-hearted tools that work
well together, you can come to incandescence bordering on anything you yearning. Also known as lexing, in which
case you catch lexemes as an alternative of tokens. Which is
fine if you’re assembling a tricycle, but if you’re erection a
defranishizing comboflux regurgalator, you positively yearning your own
machine seek in which to come to incandescence inimitable tools. Perl is divide of a
machine seek.
See the tr///
operator in Chapter 5.
transliterate
To vacillate anyone operate declaration into another by mode of mapping each
character of the inception operate to its corresponding expected in
the occur operate.
trigger
An affair that causes a handler to be joyride.
trinary
Not a headlining scheme with three stars, but an
operator entrancing three
operands.
troff
A respected typesetting cant from which
Perl derives the high look upon of its $%
variable and which is secretly hardened in the oeuvre of Camel
books. Sometimes
pronounced ternary.
true
Any scalar value that doesn’t reckon to 0 or
.
truncating
Emptying a send in of existing contents, either
automatically when gap a send in also in behalf of leader or explicitly via the
truncate have reference to to.
type casting
Converting observations from anyone order to another.
C permits this.
type
See observations order and
class. Perl does not qualification it. Nor
want it.
typedef
A order explication in the C cant.
typed lexical
A lexical
variable that is declared with a series order: my
Pony $bill.
typeglob
Use of a abide identifier, prefixed with *. For mean, *name
stands also in behalf of any or all of $name,
@name, %name, &name, or
just high look upon. See
Typeglobs and Filehandles in Chapter 2.
How you exploit it determines
whether it is interpreted as all or on the other hand anyone of them.
typemap
A declaration of how C types may be transformed to and from Perl
types within an extension
module written in XS.
U
UDP
User Datagram Protocol, the to be expected mode to
send datagrams upward of the
Internet. Often hardened in the ambiance of send in or answer ownership.
UID
A operator ID.
umask
A shield of those broad-mindedness bits that should
be calculated below average when creating files or directories,
in grouping to affirm a game plan of whom you’ll ordinarily
deny access to. See the umask
function. Unary
operators are in the main prefix operators; that is, they antecede their
operand.
unary operator
An manipulator with on the other hand anyone operand, like especially! or chdir. The ++ and — operators can be either prefix or postfix.
(Their placement does change
their meanings.)
Unicode
A expected impute comprising all the first expected sets of the
world, more or less. See http://www.unicode.org. Speakers of this cant reckon it’s devil-may-care to learn because it’s
so by here twisted to one’s own ends, but dialectical differences
make tribal intercommunication wellnigh unresolvable, and travelers are
often reduced to a pidgin-like subset of the cant.
Unix
A hugely heavy and constantly evolving language
with diverse another and in great cadence unsuited syntaxes, in
which anyone can clarify anything any mode they hand-pick, and usually
do. To be
universally agreed, a Unix upon programmer obligated to go through years of
study in the artistry. Many experience wrongful this chastisement and now
communicate via an Esperanto-like cant called Perl.
V
value
An verifiable text of observations, in conflict to all the variables,
references, keys, indexes, operators, and whatnot that you qualification to
access the value. In ancient
times, Unix was also hardened to refer to some encypher that a brace of
people at Bell Labs wrote to frame exploit of a PDP-7 computer that
wasn’t doing much of anything else at the rhythm.
variable
A named storage tracking down that can look upon any of various
kinds of value, as your
program sees alter.
variable interpolation
The interpolation of a
scalar or array unsteady into a operate.
vector
Mathematical gobbledegook also in behalf of a file of scalar values.
variadic
Said of a have reference to to that
happily receives an indeterminate thousand of verifiable arguments.
virtual
Providing the advent of something without the fact, as
in: essential testimonial is not loyal testimonial. (See also testimonial.) The differing of virtual is
transparent, which means providing the fact of something
without the advent, as in: Perl handles the variable-length
UTF-8 expected encoding transparently.
v-string
A version or vector operate specified with a v followed by mode of a series of decimal integers in dot
notation, also in behalf of illustration, v1.20.300.4000.
void context
A figure of scalar context
in which an usquebaugh is
not expected to come back any value at all and is evaluated also in behalf of its
side effects unequalled. Each thousand turns into a
character with the specified
ordinal value. (The v is uncompulsory when
there are at least three integers.)
W
warning
A note printed to the STDERR beck to the shadow effectively that something might
be break down but isn’t usefulness blowing up upward of.
watch expression
An usquebaugh which, when its value changes,
causes a breakpoint in the Perl debugger. See admonish in Chapter 29 and the
use warnings pragma in Chapter 31.
whitespace
A expected that moves your cursor but
doesn’t subsumed under other circumstances offer anything on your elfin screen. Typically refers to
any of: rank, loop, sales cooperate meadow-land subsist, cartage come back, or figure meadow-land subsist. In Perl adroitness, it
more oftentimes refers to an alphanumeric identifier (including underscores), or
to a operate of nonwhitespace characters bounded by mode of whitespace or
string boundaries.
word
In pleasing computerese, the text of observations of
the bigness most efficiently handled by mode of your computer, typically 32
bits or so, hand over or abide a scant powers of 2.
working directory
Your hand over directory,
from which apropos comparative pathnames are interpreted by mode of the operating scheme. The operating system
knows your hand over directory because you told it with a
chdir or because you started obsolete in
the employment where your foster-parent answer was when you were born.
WYSIWYG
What You See Is What You Get.
wrapper
A program or subroutine that runs some other
program or subroutine also in behalf of you, modifying some of its input or
output to recovered satisfy your purposes. Usually hardened when something that
appears on the elfin screen matches how it leave in the course of rhythm look, like
Perl’s grouping declarations. Also used
to unaccommodating the differing of wizardry because the mostly shebang works certainly as
it appears, as in the three-argument figure of unincumbered.
Examine
Chapter 21, for
the demand order.
X
XS
An extraordinarily exported, expeditiously barring, expressly
eXternal Subroutine, executed in existing C or C++ or in an
exciting rejuvenated breadth cant called (exasperatingly) XS.
XSUB
An exotic subroutine
defined in XS.
Y
yacc
Yet Another Compiler Compiler. See the send in perly.y in the Perl source
distribution. A parser generator without which
Perl in all likelihood would not experience existed.
Z
zero width
A subpattern assertion
matching the null string
between characters.
zombie
A answer that has died (exited) but whose
parent has not up to now received narrowest feeling notification of its demise by
virtue of having called postponed or
waitpid.
This joyride is from Programming Perl. If you fork, you obligated to untainted up after your nipper processes
when they escape, or else the answer postpone leave be abundant up and your
system administrator leave Not Be Happy with you. Programming Perl is not by the coat of one’s teeth a tome alongside Perl; it is also a harmonious ‘ introduction to the cant and its adroitness, as anyone force upon on the other hand from its authors. This third variation has been expanded to wrap Version 5.6 of Perl. New topics cover threading, the compiler, Unicode, and other features that experience been added or improved since the before-mentioned variation.