POSIX (Portable Operating System Interface) Portable Operating System Interface POSIX strings text strings also strings variables strings strings scalars undefined values values definedness definedness false values empty strings ("") values false single quote (') ' (single quote) double quote (") " (double quote) here documents q// operator qq// operator delimiters [] (square brackets) square brackets ([]) {} (curly braces) curly braces ({}) ( ) (parentheses) parentheses ( ) <> (angle brackets) angle brackets (<>) strings universal character code universal character code octets ASCII (American Standard Code for Information Interchange) American Standard Code for Information Interchange ASCII strings Unicode support in Perl Unicode code points, Unicode internationalization Unicode UTF-8 substrings strings accessing substrings substr( ) unpack( ) lvaluable functions functions types of = (equals sign) =~ operator equals sign (=) =~ operator s/// operator m// operator tr/// operator substr( ) operators to use with columns parsing data by variables default values for default values for variables values numbers strings variables also numbers strings variables | (vertical bar) ||= (assignment) operator vertical bar (|) ||= (assignment) operator assignment (||=) operator defined operator definedness values definedness & (ampersand), && operator ampersand (&), && operator or operator, vs. || operator | (vertical bar) || operator vs. or operator vertical bar (|) || operator vs. or operator scalars exchanging values between values exchanging between scalar variables variables scalars scalars list assignment assignment, list values converting strings between strings converting characters and values characters converting between values converting characters and values numbers converting between characters and values numbers values also values ASCII (American Standard Code for Information Interchange) characters characters converting strings between characters and values chr( ) ord( ) printf( ) sprintf( ) pack( ) unpack( ) Unicode named characters, using use charnames pragma charnames charnames charnames::viacode( ) charnames charnames::vianame( ) Unicode character database characters processing individually strings processing characters individually split( ) strings reversing elements of characters reversing words reversing reversing words or characters in strings reverse( ) split( ) using reverse( ) with join( ), using reverse( ) with Unicode strings treating as single characters strings Unicode treating as single characters diacritics \X metacharacter \ (backslash) \X metacharacter backslash (\) \X metacharacter strings canonicalizing with Unicode combined characters Unicode combined characters, canonicalizing strings with NFD( ) NFC( ) NFKD( ) NFKC( ) strings Unicode treating as octets Unicode strings treating as octets octets treating Unicode strings as use bytes pragma whitespace expanding and compressing tabs compressing tabs expanding tabs tabs whitespace Text::Tabs module $ (dollar sign) $` variable dollar sign ($) $` variable performance backreferences and $ (dollar sign) $1, $2, . . . (backreferences) dollar sign ($) $1, $2, . . . (backreferences) backreferences $1, $2, . . . $ (dollar sign) $& variable dollar sign ($) $& variable variables expanding in user input expanding variables in user input input expanding variables in strings variables also variables references symbolic forward slash (/) /e substitution modifier /(forward slash) /e substitution modifier /e substitution modifier eval( ) in substitution forward slash (/) /x pattern modifier / (forwardslash) /x pattern modifier /x pattern modifier capitalization converting case converting character case characters converting case case sensitivity converting case uppercase, converting to lowercase lowercase, converting to uppercase strings converting case converting strings case of lc( ) uc( ) \ (backslash) \L string escape backslash (\) \L string escape \ (backslash) \U string escape backslash (\) \U string escape \U string escape \L string escape \ (backslash) \l string escape backslash (\) \l string escape \l string escape \ (backslash) \u string escape backslash (\) \u string escape \u string escape lcfirst( ) ucfirst( ) tr/// operator converting case with diacritics converting case and capitalization of titles and headlines case sensitivity capitalizing titles and headlines strings headlines and titles, capitalizing tc( ) strings interpolating functions and expressions within functions interpolating within strings expressions, interpolating within strings ` (backtick) expanding backtick (`) expanding whitespace indenting here documents here documents indenting indents whitespace s/// operator stripping whitespace with dequote( ) strings reformatting paragraphs paragraphs reformatting Text::Wrap module wrapping paragraph text words wrapping paragraph text columns wrapping paragraphs by Term::ReadKey module fmt program characters escaping escaping characters strings escaping characters backslash (\) escaping characters \ (backslash) escaping characters command interpreters quotemeta( ) \ (backslash) ` string metacharacter backslash (\) ` string metacharacter ` string metacharacter \ (backslash) \E string metacharacter backslash (\) \E string metacharacter \E string metacharacter strings removing leading or trailing spaces deleting whitespace at string ends whitespace deleting leading or trailing trailing whitespace, removing leading whitespace, removing values comma-separated parsing CSV (comma-separated values) parsing parsing comma-separated data input comma-separated, parsing comma-separated values CSV Text::ParseWords module quotewords( ) Text::CSV module Text::CSV_File module parse_csv subroutines variables constants constants use constant pragma Soundex matching matching Soundex matching matching regular expressions Text::Soundex module pattern matching regular expressions Text::Metaphone module soundex( ) String::Approx module adist( ) fixstyle program strings substituting specific words words substitutions for specific psgrep program strings psgrep program typeglobs numbers scalars as numbers numbers scalars as strings converting non-numeric non-numeric strings, converting to numbers converting strings non-numeric floating-point numbers numbers floating-point numbers random random numbers strings checking if valid numbers numbers strings as valid numbers regular expressions checking strings for valid numbers trim( ) Regexp::Common module POSIX::strtod( ) is_numeric( ) Scalar::Util module looks_like_number( ) rounding floating-point numbers floating-point numbers rounding numbers floating-point rounding sprintf( ) floating-point numbers rounding printf( ) floating-point numbers, rounding int( ) ceil( ) floor( ) integers integer truncation floating-point numbers comparing comparing floating-point numbers numbers floating-point comparing sprintf( ) floating-point numbers comparing comparing floating-point numbers currency currency, comparing floating-point numbers numbers operating on integer series integers numbers also numbers Roman numerals numbers Roman numerals converting numbers Roman numerals and Roman module roman( ) random numbers generating numbers random generating rand( ) arrays randomly selecting from passwords randomly generating srand( ) Math::TrulyRandom module Math::Random module biased random numbers, generating random numbers biasing numbers random biasing gaussian_rand( ) weighted_rand( ) numbers trigonometry trigonometry operating in degrees vs. radians angles, in degrees vs. radians radians, vs. degrees converting degrees and radians Math::Trig module rad2deg( ) deg2rad( ) trigonometry sin( ) cos( ) tan( ) POSIX module trigonometric functions logarithms numbers logarithms log( ) natural logarithms log10( ) log_base( ) Math::Complex module arithmetic matrix multiplication matrix multiplication arrays matrix multiplication numbers matrix multiplication multiplication of matrices PDL (Perl Data Language) modules, matrix multiplication PDL (Perl Data Language) Perl Data Language PDL x operator scalar multiplication operator multiplication x operator complex numbers numbers complex (imaginary) imaginary numbers arithmetic complex (imaginary) numbers Math::Complex module Math::Trig module converting numbers octal numbers, converting binary numbers, converting hexadecimal numbers, converting numbers converting binary, octal, and hexadecimal hex( ) oct( ) # (pound sign), with printf( ) pound sign (#), with printf( ) comma (,) in numbers , (comma) in numbers numbers adding commas to parsing commas into numbers dot (.) periods in numbers . (dot) period in numbers regular expressions commas in numbers commify( ) strings plurals based on numbers numbers plural words based on words pluralizing, based on numbers pluralizing words Lingua::EN::Inflect module numbers primes, calculating calculating prime numbers prime numbers, calculating Math::BigInt module date and time values time date and time values seconds date and time values minutes date and time values hours date and time values days date and time values years date and time values months date and time values time zones date and time values weeks date and time values time( ) date and time values seconds passed since Epoch POSIX (Portable Operating System Interface) time( ) DMYHMS (day, month, year, hour, minute, seconds) day, month, year, hour, minute, seconds (DMYHMS) date and time values years localtime( ) gmtime( ) Time::tm module Time::localtime module Time::gmtime module localtime( ) Time::localtime/Time::gmtime gmtime( ) Time::localtime and Time::gmtime Time::Local module timelocal( ) timegm( ) Date::DateCalc module Date::Manip module date and time values today's date, finding localtime( ) today's date POSIX module today's date strftime( ) gmtime( ) today's date date and time values converting to and from Epoch seconds converting date and time to and from Epoch seconds Epoch date and time values timelocal( ) timegm( ) Time::Local module date and time values Time::Local module DMYHMS values date and time values gmtime( ) Time::timelocal module Time::gmtime module date and time values Time::timelocal module date and time values Time::gmtime module date and time values arithmetic with date and time values Date::DateCalc calc_new_date( ) Date::Calc module calc_new_date_time( ) date and time values days, calculating number between two dates Delta_Days( ) Delta_DHMS( ) date and time values days, calculating localtime( ) calculating days Day_of_week( ) Week_Number( ) Day_of_Year( ) Date::Calc module internationalization localization, first week of the year parsing date and time from strings strings parsing date and time information in date and time values parsing information from strings ParseDate( ) Date::Manip module UnixDate( ) date and time values printing printing date and time information printing ; printf( )) print( ) also print( ) localtime( ) gmtime( ) strftime( ) date and time values Date::Manip module date and time values high-resolution timers timers, high-resolution high-resolution timers Time::HiRes module date and time values Time::HiRes module gettimeofday( ) time( ) high-res timers usleep( ) ualarm( ) sleep( ) alarm( ) setitimer( ) getitimer( ) date and time values sleeps sleep( ) select( ) Time::HiRes module hopdelta program date and time values hopdelta program email tracking time path of ParseDate( ) DateCalc( ) date and time values Date::Manip module Date::Manip module arrays lists lists vs. arrays arrays vs. lists flattened lists lists flattened multidimensional arrays arrays multidimensional elements of arrays arrays arrays initializing lists initializing initializing arrays and lists CSV (comma-separated values) initializing arrays with values comma-separated initializing arrays with arrays initializing, with comma-separated values qw( ) lists printing with commas comma (,) printing lists with , (comma) printing lists with printing lists with commas arrays printing elements with commas commify_series program arrays changing size of size arrays, changing $ (dollar sign) $#ARRAY variable dollar sign ($) $#ARRAY variable $#ARRAY variable arrays last valid index ($#ARRAY) arrays sparse, implementing implementing sparse arrays arrays iterating through all elements lists iterating through elements loop variables iterator variables variables loop (iterator) variables $ (dollar sign) $_ variable dollar sign ($) $_ variable $ (dollar sign) $_ variable accidental clobbering dollar sign ($) $_ variable accidental clobbering aliases for list elements references iterating over arrays by arrays iterating over by reference iterations arrays lists lists extracting elements arrays extracting elements unique list elements, extracting duplicate list elements, extracting hashes arrays unions, intersections, differences lists unions, intersections, differences unions of lists differences of lists intersections on lists set theory hashes for list unions, intersections, differences hashes slices of lists unions, intersections, differences differences of lists computing unions of lists computing intersections on lists symmetric difference simple difference differences of lists simple and symmetric arrays appending multiple appending arrays to each other push( ) arrays reversing elements of reversing array elements lists reversing elements of reverse( ) arrays processing multiple elements lists processing multiple elements splice( ) @ (at sign) splice( ) at sign (@) splice( ) arrays iterating through elements lists iterating through elements last( ) foreach loop List::Util module arrays extracting subsets lists extracting subsets extracting from arrays arrays extracting array subsets grep operator arrays extracting subsets with grep arrays sorting elements numerically sorting array elements numerically sort( ) < (left angle bracket) <=> numerical comparison operator left angle bracket (<) <=> numerical comparison operator numerical comparison (<=>) operator revnum( ) lists sorting by computable field sorting arrays and lists by computable field arrays sorting by computable field sort( ) by computable field | (vertical bar) || operator separating multiple comparisons vertical bar (|) || operator separating multiple comparisons User::pwent module map( ) lists circular arrays circular circular lists unshift( ), circular lists pop( ), circular lists push( ) circular lists shift( ), circular lists lists circular random randomizing arrays arrays randomizing lists randomizing element order sorting randomizing array element order shuffle( ) arrays List::Util module arrays words program lists words program words program columns outputting text by sorting text into columns words sorting into columns whitespace sorted text in columns and permute program arrays permute program lists permute programs permutations, generating all possible memoizing technique factorial( ) n2perm( ) hashes associative arrays hashes % (percent sign) hashes percent sign (%) hashes $ (dollar sign) hashes dollar sign ($) hashes indices of hash elements strings hash element indices hashes arrays and initializing hashes hashes initializing = (equals sign) => operator equals sign (=) => operator hash-list equivalence hashes adding elements to elements of hashes hashes hashes testing for keys exists( ) deleting hash elements hashes deleting elements of delete( ) delete( ) compared to undef( ) undef( ), compared to delete( ) traversing hashes hashes traversing while loop, traversing hashes keys( ) each( ) foreach loop traversing hashes keys( ) hashes traversing values( ), traversing hashes each( ) hashes traversing printing hashes hashes printing map( ) printing hashes Dumpvalue module keys( ) hashes ordering elements each( ) hashes ordering elements of hashes retrieving in insertion order Tie::IxHash module push( ) Tie::IxHash module and hashes multiple values per key exists( ) multiple hash key values delete( ) multiple hash key values inverting hashes hashes inverting reverse( ) inverting hashes reversing hashes foodfind program hashes sorting elements sorting hash elements keys( ) hashes sorting sort( ) hashes hashes merging merging hashes each( ) hashes merging memory requirements for hash merging technique hashes comparing keys of comparing keys of hashes keys( ) Tie::RefHash module hashes references as elements references as hash values preallocating memory for hashes memory preallocating for hashes hashes presizing size hashes, preallocating for keys( ) hashes presizing performance presizing hashes hashes finding most common anything finding most common anything hashes counting how often something appears data, relationships between hashes representing data relationships data, relationships between variables also variables hashes representing relationships between data dutree program hashes dutree program sorting du command output du command, sorting output of whitespace sorting du command output columns arranging du command output output( ) regular expressions greedy pattern matching regular expressions greedy vs. non-greedy matching eager pattern matching regular expressions eager matching non-greedy pattern matching NFA (non-deterministic finite automata) non-deterministic finite automata (NFA) backtracking in pattern matching regular expressions backtracking regular expressions pattern-matching modifiers forward slash (/) /i pattern-matching modifier / (forward slash) /i pattern-matching modifier /i pattern-matching modifier forward slash (/) /g pattern-matching modifier / (forward slash) /g pattern-matching modifier /g pattern-matching modifier forward slash (/) /s pattern-matching modifier / (forward slash) /s pattern-matching modifier /s pattern-matching modifier forward slash (/) /m pattern-matching modifier / (forwardslash) /m pattern-matching modifier /m pattern-matching modifier forward slash (/) /e substitution modifier /(forward slash) /e substitution modifier /e substitution modifier $ (dollar sign) $* variable (deprecated) dollar sign ($) $* variable (deprecated) eval( ) in substitution $ (dollar sign) $1, $2, . . . (backreferences) dollar sign ($) $1, $2, . . . (backreferences) backreferences \1, \2, . . . backreferences $1, $2, . . . $ (dollar sign) $+ variable dollar sign ($) $+ variable $ (dollar sign) $& variable dollar sign ($) $& variable substr( ) pattern matching variables regular expressions copying and substituting strings copying and substituting substitution within strings ( ) (parentheses) substitution parentheses ( ) substitution characters matching letters regular expressions matching letters strings matching letters strings matching words words pattern matching regular expressions matching words whitespace matching words regular expressions commenting comments in regular expressions forward slash (/) /x pattern modifier comments in regular expressions / (forwardslash) /x pattern modifier comments in regular expressions /x pattern modifier comments in regular expressions qr// operator comments in regular expressions regular expressions matching Nth occurrence /g pattern-matching modifier finding Nth matches forward slash (/) /g pattern-matching modifier finding Nth matches / (forwardslash) /g pattern-matching modifier finding Nth matches progressive matching regular expressions progressive matching regular expressions matching within multiple lines whitespace matching within multiple lines line breaks matching within multiple lines newlines line breaks whitespace carriage returns line breaks whitespace forward slash (/) /m pattern-matching modifier multiple lines / (forwardslash) /m pattern-matching modifier multiple lines /m pattern-matching modifier multiple lines forward slash (/) /s pattern-matching modifier multiple lines / (forwardslash) /s pattern-matching modifier multiple lines /s pattern-matching modifier multiple lines $ (dollar sign) $. variable dollar sign ($) $. variable pattern separators, reading data with input reading records with pattern separators CSV (comma-separated values) reading records from records reading with pattern separators reading records with pattern separators records comma-separated CSV split( ) reading records with pattern separators line breaks extracting ranges of lines whitespace extracting ranges of lines regular expressions extracting ranges of lines dot (.) . . and . . . range operators . (dot) . . and . . . range operators wildcards (shell) for regular expression matching regular expressions matching shell globs as shell wildcards for regular expression matching converting shell wildcards for regular expression matching File::KGlob module forward slash (/) /o pattern-matching modifier / (forwardslash) /o pattern-matching modifier /o pattern-matching modifier qr// operator interpolated matches regular expressions testing for invalid patterns $ (dollar sign) $@ variable dollar sign ($) $@ variable capitalization honoring locale when matching regular expressions honoring locale settings locale settings case sensitivity honoring locale when matching use pragmas use locale pragma regular expressions fuzzy matching approximate matching fuzzy matching words fuzzy matching String::Approx module regular expressions matching from where last pattern ended forward slash (/) /g pattern-matching modifier where last pattern ended / (forwardslash) /g pattern-matching modifier where last pattern ended /g pattern-matching modifier where last pattern ended regular expressions \G anchor \ (backslash) \G anchor backslash (\) \G anchor \G anchor pos( ) regular expressions greedy vs. non-greedy matching non-greedy pattern matching vs. greedy pattern matching greedy pattern matching vs. non-greedy pattern matching maximal matching quantifiers minimal matching quantifiers regular expressions doubled words words double, finding double words, finding strings doubled words, finding $ (dollar sign) $1, $2, . . . (backreferences) finding doubled words dollar sign ($) $1, $2, . . . (backreferences) finding doubled words backreferences \1, \2, . . . finding doubled words backreferences $1, $2, . . . finding doubled words \ (backslash) \1, \2, . . . (backreferences) backslash (\) \1, \2, . . . (backreferences) regular expressions backtracking backtracking finding doubled words regular expressions matching nested patterns nested pattern matching Text::Balanced module extract_bracketed( ), matching nested patterns Regexp::Common module Text::Balanced module regular expressions logical functionality in AND functionality in regular expressions OR functionality in regular expressions NOT functionality in regular expressions logical functionality in patterns Boolean connectives in patterns HTML forms Boolean connectives in patterns configuration files Boolean connectives in patterns minimal matching Boolean connectives in patterns maximal matching Boolean connectives in patterns regular expressions pattern-matching modifiers Boolean connectives - (minus sign), modifiers and minus sign (-), modifiers and regular expressions email addresses email matching valid addresses addresses, email, matching personal identification number (PIN) PIN (personal identification number) Email::Valid module abbreviations, matching regular expressions matching abbreviations words matching abbreviations Text::Abbrev module Text::Abbrev module abbrev( ) regular expressions urlify program urlify program URLs (Uniform Resource Locators) putting HTML links around HTML putting links around URLs tcgrep program regular expressions tcgrep program finding patterns regular expressions searching for patterns regular expressions grep program (Unix), Perl rewrite of regular expressions useful, list of file access filehandles file access filehandles blocking( ) IO::File module STDIN filehandle STDOUT filehandle STDERR filehandle file access filehandles filehandles standard standard filehandles I/O operations access modes file access access modes open( ) file access modes syscalls system calls line input operator operators line input input line input operator records reading < (left angle bracket) <FH> line input operator left angle bracket (<) <FH> line input operator reading records < (left angle bracket) file-access modes > (right angle bracket), file-access modes left angle bracket (<) file-access modes right angle bracket (>), file-access modes ARGV line input operator filehandles seek offset seek offset, filehandles close( ) filehandles portability closing filehandles STDOUT filehandle $ (dollar sign) $| variable dollar sign ($) $| variable buffered input/output unbuffered input/output I/O operations buffering I/O layers I/O layers unix unix layer I/O layers stdio stdio layer opening files files opening open( ) filehandles sysopen( ) filehandles file access access modes < (left angle bracket) file-access modes left angle bracket (<) file-access modes > (right angle bracket), file-access modes right angle bracket (>), file-access modes + (plus sign), file-access modes plus sign (+), file-access modes O_ flags umask values filenames unusual, opening files with files with unusual filenames, opening open( ) unusual filenames sysopen( ) unusual filenames tilde (~), in filenames, expanding filenames expanding tildes in ~ (tilde), in filenames, expanding glob( ) substitution expanding filenames URLs (Uniform Resource Locators) expanding tildes in filenames File::Glob module filenames reporting in errors errors reporting filenames in filehandles reporting filenames in errors filenames using as filehandle filehandles using filename as errors exceptions also exceptions * (asterisk), typeglobs asterisk (*), typeglobs filehandles storing in variables variables filehandles in open( ) filehandles storing in variables typeglobs filehandles autovivified print( ) filehandles storing in variables printf( ) storing filehandles in variables indirect object notation IO::Handle module getline( ) Symbol module qualify_to_ref( ) filehandles caching caching open filehandles file access filehandles caching open FileCache module open( ) caching open filehandles cacheout( ) NOFILE constant filehandles printing to multiple simultaneously printing to multiple filehandles simultaneously file access filehandles printing to multiple foreach loop printing to multiple filehandles print( ) filehandles outputting to multiple IO::Tee module file access opening and closing file descriptors opening file descriptors close( ) file descriptors file descriptors, opening and closing < (left angle bracket) <&= and <& open modes left angle bracket (<) <&= and <& open modes new_from_fd( ) IO::Handle module POSIX::close( ) MHCONTEXTFD environment variable environment variables MHCONTEXTFD POSIX::close( ) copying filehandles filehandles copying file access filehandles copying aliases for filehandles typeglobs filehandles with, creating alias for I/O layers stdio stdio layer open( ) file descriptors, creating aliases for files creating temporary creating temporary files File::Temp module tempfile( ) open( ) creating temporary files file access storing files in program text files storing in program text __DATA__ token __END__ token $ (dollar sign) $0 variable dollar sign ($) $0 variable $0 variable filenames filtering as input filtering filenames as input file access filtering filename input <> (angle brackets) line input operator angle brackets (<>) line input operator - (hyphen) -p command-line option writing filters hyphen (-) -p command-line option writing filters -p command-line option writing filters - (hyphen) -n command-line option, writing filters hyphen (-) -n command-line option, writing filters -n command-line option, writing filters filenames filtering as input command-line options filtering filenames as input command-line options file access filtering filename input command-line options - (hyphen) -i command-line option writing filters hyphen (-) -i command-line option writing filters -i command-line option writing filters - (hyphen) -a command-line option, writing filters hyphen (-) -a command-line option, writing filters -a command-line option, writing filters - (hyphen) -e command-line option, writing filters hyphen (-) -e command-line option, writing filters -e command-line option, writing filters LINE: (implicit loop label) file contents modifying with temporary files temporary files, modifying files with editing files file contents modifying files file contents file access editing files file contents rename( ) modifying files with temporary files file contents modifying with -i switch -p command-line option modifying files with - (hyphen) -p command-line option modifying files with hyphen (-) -p command-line option modifying files with -i command-line option modifying files with - (hyphen) -i command-line option modifying files with hyphen (-) -i command-line option modifying files with $ (dollar sign) $^I variable dollar sign ($) $^I variable $ (dollar sign) $. variable dollar sign ($) $. variable file contents modifying without temporary files temporary files, modifying files without file access locking files locking files blocking file access files locking flock( ) advisory locking locking files advisory locking files locking advisory locking shared locks exclusive locks close( ) file locks File::NFSLock module flock( ) compared to SysV lockf( ) fnctl( ), locking files file access flushing output flushing output I/O operations flushing output output flushing $ (dollar sign) $| variable dollar sign ($) $| variable autoflush( ) buffered input/output unbuffered input/output I/O operations buffering I/O layers Unix I/O layers I/O layers unix unix layer I/O operations non-blocking non-blocking I/O filehandles non-blocking I/O file access non-blocking I/O O_ flags O_NONBLOCK option sysopen( ) non-blocking I/O $ (dollar sign) $! variable dollar sign ($) $! variable file access unread bytes, determining number of unread bytes, determining number bytes, determining number of unread FIONREAD call ioctl( ) filehandles reading from many file access filehandles reading from multiple reading files file access file contents select( ) reading from multiple filehandles IO::Select module new( ) file access filehandles reading a line from, without blocking filehandles reading a line from, without blocking blocking file access reading a line from a filehandle without sysreadline( ) IO::Handle module can_read( ) locking files netlock program blocking file access netlock program netlock program files locking netlock program file access locking files netlock program File::LockDir module lockarea program blocking file access region-specific locks file access locking files region-specific locks locking region-specific locks struct_flock( ), lockarea program $ (dollar sign) $^O variable dollar sign ($) $^O variable processes groups signals process groups file contents line input operator operators line input input line input operator <FH> line input operator $ (dollar sign) $_ variable dollar sign ($) $_ variable $ (dollar sign) $/ variable dollar sign ($) $/ variable -0 command-line option - (hyphen) -0 command-line option hyphen (-) -0 command-line option file contents I/O layers I/O layers I/O layers crlf crlf I/O layer I/O layers utf8 utf8 I/O layer I/O layers raw raw I/O layer I/O layers bytes bytes I/O layer crlf I/O layer I/O layers crlf binmode( ) file contents fixed-length records records fixed-length fixed-length records read( ) I/O layers read( ) fixed-length records truncate( ) tell( ) seek( ) buffered input/output unbuffered input/output I/O operations buffering sysread( ) syswrite( ) sysseek( ) file contents reading lines with continuation characters continuation characters, reading data with line breaks reading with continuation characters file contents counting lines, paragraphs, and records line breaks lines in files counting counting lines in files paragraphs counting in files records counting in files lines counting in files wc program words processing all in file file contents processing all words in split( ) processing all words in file m// operator file contents reading backwards paragraphs reading files backwards by line breaks reading files backwards arrays reading files backwards lines reading files backward by Tie::File module file contents continually growing files, reading trailing growing files clearerr( ) IO::Handle module seek( ) File::stat module random lines in files selecting file contents random lines from, selecting line breaks lines in files selecting random rand( ) random lines in files ordering of file contents randomizing line order line breaks lines in files randomizing order sorting randomizing file line order List::Util module shuffle( ) lines file contents extracting single line lines single, extracting from file Tie::File module DB_File module DB_RECNO access method variable-length text fields file contents variable-length text fields input extracting variable-length fields records variable-length split( ) variable-length text fields $ (dollar sign) $_ variable dollar sign ($) $_ variable deleting files last line of files deleting last line of line breaks lines in files deleting last Tie::File module binary files file contents processing binary files files binary binmode( ) I/O layers crlf crlf I/O layer I/O layers raw raw I/O layer file contents random access input/output random random-access I/O I/O operations random-access I/O input random-access I/O output random access I/O records random-access I/O read( ) random-access files file contents random access updating random random-access files, updating files random-access, updating updating random-access files pack( ) weekearly program file contents reading null-terminated strings from binary files binary files reading null-terminated strings strings null-terminated, reading from binary files files binary reading null-terminated strings <> (angle brackets) reading strings from binary files angle brackets (<>) reading strings from binary files bgets program file contents fixed-length records reading fixed-length records reading records fixed-length reading read( ) fixed-length records unpack( ) fixed-length records file contents configuration files, reading configuration files reading files configuration, reading do( ) configuration files, reading file contents testing for trustworthiness security testing files for trustworthiness permissions testing files for trustworthiness stat( ) is_safe( ) files treating as arrays arrays treating files as file contents treating files as arrays Tie::File module files as arrays I/O layers setting default setting default I/O layers file contents setting default I/O layers open pragma file contents reading and writing Unicode from filehandles filehandles reading and writing Unicode from Unicode reading and writing from filehandles I/O layers reading and writing Unicode from filehandles Encode module UTF-8 memory encodings and converting Microsoft files to Unicode Unicode converting Microsoft files to files Microsoft, converting to Unicode file contents converting Microsoft files to Unicode browsers support for Unicode fonts web browsers browsers text editors, support for Unicode fonts fonts, Unicode, support for -C command-line switch -C command-line switch PERL_UNICODE environment variable environment variables PERL_UNICODE file contents comparing two files files comparing file contents comparing contents of two files File::Compare module compare( ) filehandles comparing comparing filehandles Text::Diff module strings treating as files files treating strings as file contents treating strings as files I/O layers scalars tailwtmp program wtmp file, adding records to file contents adding records to wtmp file records wtmp file tctee program file contents tctee program magic open ARGV, magic magic ARGV open( ) magic open laston program file contents viewing lastlog file information records lastlog file flat file index program fixed-length records flat-file index program indices fixed-length records program directories file access directories file contents also directories file contents file contents directories; file access filesystem directories forward slash (/) root directory / (forwardslash) root directory atime field, inode structure ctime field, inode structure mtime field, inode structure inode structure stat( ) _ (underscore), file stat cache underscore (_), file stat cache File::stat module file test operators opendir( ) readdir( ) closedir( ) sorting directory contents filenames sorting directories sorting contents of hard links symbolic links directory handles directories timestamps timestamps file access timestamps date and time values file access timestamps stat( ) timestamps utime( ), timestamps directories deleting files files deleting deleting files file access copying and moving files directories copying and moving files copying files File::Copy module File::Copy module copy( ) move( ) directories multiple names for same file filenames multiple, for same file $ (dollar sign) $; variable dollar sign ($) $; variable multidimensional associative array emulation syntax file access processing all files in directories directories processing all files in files processing all in directories opendir( ) readdir( ) rewinddir( ) seekdir( ) filenames globbing regular expressions globbing filenames globbing regular expressions glob( ) <> (angle brackets) globbing angle brackets (<>) opendir( ) globbing readdir( ) globbing directories processing all files in recursively recursively processing files in directories file access processing all files in directories recursively processes recursively processing files in directories File::Find module -d file test operator deleting directories and their contents directories deleting finddepth( ) File::Find module removing directories recursively rmtree( ) File::Path module rmdir( ) unlink( ), removing directories and contents filenames renaming directories renaming files foreach loop renaming files rename( ) rename script, example parsing filenames filenames parsing directories parsing filenames File::Basename module dirname( ) basename( ), splitting filenames fileparse( ) $ (dollar sign) $^O variable dollar sign ($) $^O variable permissions symbolic file, instead of octal values octal values, working with symbolic file permissions instead Stat::lsMode module File::chmod module directories recursively duplicating copying directory trees symbolic links duplicating directory trees symirror program lst program directories sorting contents of sorting directory contents filenames sorting subroutines sub keyword do( ) require operator use operator subroutines access arguments arguments, subroutine @ (at sign) @_ array at sign (@) @_ array subroutines private variables variables private, for subroutines private subroutine variables my operator scope of subroutine variables lexical scope subroutines persistent private variables variables persistent private, for subroutines persistent private subroutine variables subroutines currently running, name of names of current subroutines. determining caller( ) names of subroutines __LINE__ symbol __PACKAGE__ symbol __FILE__ symbol whoami( ) whowasi( ) references passing arrays and hashes by arguments, subroutine passing by reference subroutines passing arrays and hashes by reference passing arrays and hashes by reference backslash (\) passing arrays and hashes by references backslash (\) passing arrays and hashes by references subroutines return context, detecting return context, subroutines scalars detecting scalar context list context, detecting wantarray( ) subroutines passing by named parameter arguments, subroutine passing by named parameter passing by named parameter name-value pairs, passing subroutines by named parameter deleting selected subroutine return values subroutines return values skipping selected return values, subroutines skipping selected scalar operator, list version subroutines return values returning by reference references returning subroutines by return values, subroutines returning by reference subroutines return values returning failure return values, subroutines returning failure errors subroutines returning failure from failure, returning from subroutines return statement fcntl( ), return values ioctl( ) return values prototypes subroutines prototypes for functions arguments, subroutine function prototypes ( ) (parentheses) prototyping functions parentheses ( ) prototyping functions hashes adding elements to hpush( ) subroutines exception handling exceptions handling in subroutines errors subroutines exceptions in die function $ (dollar sign) $@ variable dollar sign ($) $@ variable global values, saving subroutines saving global values local operator local( ) global values filehandles local filehandles passing dynamic scoping runtime scoping typeglobs global values subroutines localizing localizing functions local( ) redefining functions aliases for functions importing from modules modules importing from subroutines trapping undefined function calls trapping undefined function calls errors trapping undefined function calls exceptions trapping undefined function calls AUTOLOAD mechanism trapping undefining function calls subroutines nesting nested subroutines closures inner( ) outer( ) subroutines writing switch statement switch statement writing Switch module switch construct sorting mail email sorting subroutines email sorter subject, sorting mail by date and time values sorting mail by references typed referents references typed references reference count - (hyphen) -> (arrow) operator hyphen (-) -> (arrow) operator - (hyphen) -> (infix) notation hyphen (-) -> (infix) notation arrow (->) operator infix (->) notation ref( ) [] (square brackets) creating anonymous arrays and hashes square brackets ([]) creating anonymous arrays and hashes {} (curly braces) creating anonymous arrays and hashes curly braces ({}) creating anonymous arrays and hashes references anonymous data anonymous data data structures complex, creating on the fly arrays anonymous hashes anonymous \ (backslash) creating references backslash (\) creating references autovivification references autovivification memory deallocation records hashes as records references to arrays arrays references to @ (at sign) references to arrays at sign (@) references to arrays \ (backslash) references to arrays backslash (\) references to arrays hashes of arrays arrays hashes of references hashes of arrays references hashes of arrays push( ) references to hashes hashes references to dereferencing references references to functions functions references to closures references to scalars scalars references to backslash (\) references to scalars \ (backslash) references to scalars arrays of scalar references references arrays of scalar references scalars arrays of scalar references \ (backslash) creating arrays backslash (\) creating arrays closures as objects objects closures as references closures as objects records closures as objects references to methods methods references to creating references to methods records constructing records reading and writing to text files file contents reading and writing hash records to file hashes reading and writing records to file reading and writing hash records to text files printing data structures data structures printing x command (Perl debugger) Data::Dumper module data structures copying copying data structures dclone( ) Storable module surface copies shallow copies copying surface vs. deep copies deep copies data structures storing to disk store( ) retrieve( ) nstore( ) data structures transparently persistent persistent data structures MLDBM module DB_File module GDBM_File module references weak, coping with circular data structures using data structures circular, coping with, using weak references Devel::Peek module Dump( ) WeakRef module weaken( ) Scalar::Util module outline programs data structures outlines records binary tree structures tree structures binary trees data structures binary trees packages : (colon) package names colon (:) package names package statement modules require operator use pragmas pragmas importing from modules .pm filename extension : (colon) module names colon (:) module names exporting to modules Exporter module libraries file extensions CPAN (Comprehensive Perl Archive Network) Comprehensive Perl Archive Network CPAN modules designing interface for Exporter module $VERSION variable (use pragma) $ (dollar sign) $VERSION variable (use pragma) dollar sign ($) $VERSION variable (use pragma) @EXPORT array (use pragma) @ (at sign) @EXPORT array (use pragma) at sign (@) @EXPORT array (use pragma) @EXPORT_OK array (use pragma) @ (at sign) @EXPORT_OK array (use pragma) at sign (@) @EXPORT_OK array (use pragma) @EXPORT_TAGS array (use pragma) @ (at sign) @EXPORT_TAGS array (use pragma) at sign (@) @EXPORT_TAGS array (use pragma) errors trapping in require and use statements use pragmas trapping errors in require operator trapping errors in modules errors trapping in use and require statements eval( ) with require and use statements runtime loading modules at modules loading at runtime use autouse pragma delaying module loading autouse pragma ( ) (parentheses) autouse pragma parentheses ( ) autouse pragma private module variables subroutines private for modules variables private, for modules modules private variables packages private variables private function to variable functions private for variables variables functions private for packages determining current calling caller( ) __PACKAGE__ symbol Symbol::qualify( ) filehandles passing modules automatic setup and cleanup cleaning up after modules initializing modules $ (dollar sign) $^F variable dollar sign ($) $^F variable directories of modules modules directories of -I command-line switch - (hyphen) -I command-line switch hyphen (-) -I command-line switch @INC array @ (at sign) @INC array at sign (@) @INC array PERL5LIB environment variable use lib pragma FindBin module modules preparing for distribution h2xs tool XS interface CPAN (Comprehensive Perl Archive Network) registering as developer modules loading loading modules SelfLoader module AutoLoader module packages overriding built-in functions subroutines built-in, overriding overriding built-in functions modules overriding built-in functions Cwd module errors reporting like built-ins warnings reporting like built-ins modules errors reporting like built-ins Carp module croak( ) confess( ) $ (dollar sign) $^W variable dollar sign ($) $^W variable warnings customizing customizing warnings warnings::enabled( ) warnings::register pragma packages referring to indirectly symbolic links to packages references to packages, indirect references symbolic symbolic references closures typeglobs assigning references to h2ph tool, translating C header files C header files, translating with h2ph files C header, translating with h2ph .ph filename extension ioctl( ) windows size of, determining h2xs tool making a module with C code modules writing in C C writing modules in XS interface extension modules, C, building C extension modules, building building C extension modules Inline::C module modules documenting with pod comments pod documentation for modules pod documentation pod2html pod2text tools pod2man converting pod into other languages pod converting into other languages whitespace in pod documentation paragraphs in pod documentation =for escape pod directive = (equals sign) =begin pod directive equals sign (=) =begin pod directive =begin pod directive = (equals sign) =end pod directive equals sign (=) =end pod directive =end pod directive installing modules from CPAN building modules from CPAN CPAN (Comprehensive Perl Archive Network) building and installing modules from modules CPAN CPAN CPANPLUS module modules template for templates for modules modules finding versions and descriptions of finding versions and descriptions of modules CPANPLUS module object-oriented programming objects classes methods bless( ) ref( ) methods - (hyphen) -> (arrow) operator hyphen (-) -> (arrow) operator arrow (->) operator invocant constructors objects constructing destructors objects destroying public methods private methods methods private and public class methods instance methods prototypes AUTOLOAD mechanism methods generating with AUTOLOAD classes generating methods with AUTOLOAD inheritance classes inheritance superclasses single inheritance multiple inheritance indirect notation methods indirect notation object-oriented programming instance methods base class generic classes superclasses classes superclasses classes generic class methods object methods constructors objects constructing bless( ) initializers constructors destructors objects destroying garbage collection memory garbage collection instance data managing objects managing instance data attributes, object object attributes methods Alias module class data objects managing class data static data members class methods data types classes as structs classes as structs structs, classes as class attributes class data Class::Struct module struct( ) Net::hostent module objects cloning parent objects parent classes cloning objects copying parent objects constructors cloning parent objects copy constructors dclone( ) Storable module methods invoking indirectly can( ) UNIVERSAL module subclasses, determining membership classes determining subclass membership objects determining subclass membership isa( ) VERSION( ) inheritance classes inheritance empty base class test base class empty base class test functions vs. methods methods vs. functions overridden methods methods overridden constructors accessing overridden methods superclasses accessing overridden methods parent classes accessing overridden methods classes accessing overridden methods SUPER pseudoclass AUTOLOAD mechanism generating methods methods generating with AUTOLOAD classes generating methods with AUTOLOAD circular data structures garbage collection circular data structures and memory garbage collection circular data structures and class data circular data structures instance data circular data structures data types circular data structures self-referential data structures references self-referential structures overloading operators operators overloading use overload pragma StrNum class (example) strings numeric operators with FixNum class numbers decimal places, controlling output controlling decimal places places( ) variables magic, creating creating magic variables magic variables, creating objects tied objects filehandles tied handles filehandles tie( ) FETCH( ) STORE( ) TIESCALAR( ) TIEARRAY( ) TIEHASH( ) TIEHANDLE( ) Tie::Scalar module Tie::Array module Tie::Hash module Tie::Handle module $ (dollar sign) $_ variable outlawing unauthorized use dollar sign ($) $_ variable outlawing unauthorized use unimport( ) outlaw $_ program nounder_demo program hashes ties for appendhash_demo program capitalization case-insensitive hashes case sensitivity hashes folded_demo program hashes lookups by key or value references as hash keys revhash_demo program database access access to databases database access DBM libraries libraries DBM NDBM files GDBM files SDBM files Berkeley DB library code size, library disk usage, library MLDBM module DBD::SQLite module DBM files making and using database access DBM files making and using tie( ) DBM files making and using userstats program DBM files emptying deleting emptying DBM files database access DBM files emptying tie( ) DBM files emptying DBM files converting between converting DBM files database access DBM files converting between db2gdbm program DBM files GDBM files GDBM files db2gdbm program merging DBM files DBM files merging database access DBM files merging sorting DBM files DBM files sorting database access DBM files sorting DB_File module sorting large DBM files B-tree implementation, DB_File DBM files complex data in database access DBM files storing complex data in MLDBM module persistent database data database access persistent data MLDBM module persistent data SQL queries saving results to Excel or CSV Excel, saving SQL query results to CSV files, saving results of SQL queries DBIx::Dump module SQL queries executing using DBI database access SQL queries DBI module DBD module single quote (') escaping ' (single quote) escaping double quote (") escaping " (double quote) escaping quote( ) errors database database access dealing with errors SQL queries repeating efficiently binding, databases SQL queries building programmatically map( ) building SQL queries programmatically database access SQL queries do( ) finding number of rows returned by SQL queries database access using transactions commit( ) rollback( ) database access viewing data one page at a time SQL queries querying CSV files DBD::CSV module SQL queries without database server servers database, using SQL without DBD::SQLite module ggh program history.db file, grepping database access ggh program Netscape history.db file user interfaces line mode interfaces full-screen mode user interfaces full-screen mode GUIs (graphical user interfaces) graphical user interfaces (GUIs) login sessions curses toolkit Tk toolkit programs command-line arguments, parsing command-line arguments, parsing parsing command-line arguments characters parsing command-line arguments input parsing command-line arguments Getopt::Std module Getopt::Long module getopt( ) getopts( ) GetOptions( ) interactivity, testing for programs testing if running interactively user interfaces testing programs if running interactively -t command-line option - (hyphen) -t command-line option hyphen (-) -t command-line option tty devices, testing for deleting clearing the screen user interfaces clearing the screen Term::Cap module clear command, clearing the screen user interfaces determining window size windows size of, determining size window or terminal, determining Term::ReadKey module determining window size GetTerminalSize( ) text changing color color of text, changing user interfaces text color characters text color, changing words text color, changing strings text color, changing Term::ANSIColor module color( ) unbuffered input/output input reading from keyboard user interfaces reading from keyboard keyboard input Term::ReadKey module reading from keyboard cbreak mode bell, ringing alarm, ringing user interfaces ringing terminal bell backslash (\) \a for terminal bell \ (backslash) \a for terminal bell \a for terminal bell visual bell termios interface user interfaces manipulating terminal directly POSIX (Portable Operating System Interface) termios interface terminal user interfaces HotKey module input waiting, checking for keyboard input checking for user interfaces checking for waiting input Term::ReadKey module checking for waiting input input reading passwords passwords reading without echo echo and password input user interfaces reading passwords without echo security reading passwords without echo passwords reading without echo Term::ReadKey module reading passwords noecho input mode editing input user interfaces editing input input editing keyboard input input also input Term::ReadLine module Term::ReadLine::Gnu module user interfaces managing screen screen user interfaces Curses module rep program perlmenu module user interfaces controlling programs with Expect Expect module controlling programs with programs controlling with Expect Expect module IO::Pty module IO::Stty module input Expect-controlled programs and user interfaces menus, creating with Tk Tk toolkit menus creating menus with Tk toolkit Menubutton widget, Tk Frame widget, Tk labels, menu command entry, menu items checkbutton menu entries radiobuttons cascading menu entries tear-off menus user interfaces dialog boxes, creating with Tk Tk toolkit dialog boxes dialog boxes with Tk toolkit windows dialog boxes, creating with Tk DialogBox widget, Tk warn( ), dialog box for user interfaces Tk resize events Tk toolkit resize events size Tk window resize events events, Tk resize Configure event, Tk pack( ) with Tk resize events windows DOS shell, removing deleting DOS shell window user interfaces DOS shell window, removing DOS shell window, removing Tk toolkit DOS shell window, removing Win32::Console module user interfaces graphing data creating charts GD::Graph modules user interfaces thumbnailing images images thumbnailing Image::Magick module Resize( ), thumbnailing images user interfaces adding text to images images adding text to text adding to images GD module Term::Cap module user interfaces tcapdemo program tcapdemo program Tk toolkit tkshufflepod program sorting pod =head1 sections tkshufflepod program modules documenting with pod sorting =head1 sections pod documentation sorting =head1 sections graphbox program GD::Graph modules GD::Graph::Bars module user interfaces graphing data creating charts processes processes creating creating processes pipe( ) zombies processes zombies signals processes signals SIGINT signal SIGQUIT signal SIGTERM signal SIGUSR1/SIGUSR2 signals SIGPIPE signal SIGALRM signal SIGHUP signal SIGCHLD signal output gathering from programs programs gathering output from processes gathering output backtick (`) gathering program output ` (backtick) gathering program output programs running multiple processes programs running multiple system( ) running multiple programs backtick (`) running another program ` (backtick) running another program $ (dollar sign) $? variable dollar sign ($) $? variable $ (dollar sign) $? variable dollar sign ($) $? variable programs replacing processes programs replacing exec( ) replacing programs $ (dollar sign) $$ variable dollar sign ($) $$ variable output writing to other programs input reading from other programs processes programs reading from and writing to programs reading from and writing to I/O operations reading and writing to other programs open( ) reading from other programs write( ) SIGPIPE signal filtering output output filtering processes filtering output programs filtering output open( ) filtering output STDOUT filehandle filtering output input preprocessing processes preprocessing input programs preprocessing input I/O operations preprocessing input STDIN filehandle preprocessing input magic open magic ARGV ARGV, magic errors reading STDERR from programs STDERR filehandle reading from programs programs reading STDERR from processes programs reading STDERR from input reading STDERR from programs input controlling for other programs programs controlling input/output of processes controlling input/output buffered input/output controlling for other programs I/O operations controlling for other programs output controlling for other programs IPC::Open2 module errors controlling for other programs STDERR filehandle controlling for other programs input controlling for other programs IPC::Open3 module IO::Select module IO::Select module processes communicating between pipe( ) fork( ) autoflush( ) open( ) processes fork( ) processes processes imitating files with named pipes named pipes FIFOs (named pipes) variables sharing among different processes sharing variables among processes processes sharing variables among SysV IPC IPC::Shareable module $ (dollar sign) $$ variable dollar sign ($) $$ variable signals listing available kill command listing available signals processes signals listing available kill command Config module signals sending processes signals sending kill command sending signals processes groups signals process groups signal handlers processes signal handlers installing signal handlers handlers for signals signal handlers signals handlers for signal handlers %SIG hash % (percent sign) %SIG hash percent sign (%) %SIG hash __DIE__ signal __WARN__ signal overriding signal handlers signal handlers overriding processes signal handlers overriding local( ) overriding signal handlers signal handlers writing processes signal handlers writing writing signal handlers Ctrl-C, catching processes catching Ctrl-C SIGINT signal zombies avoiding processes zombies avoiding fork( ) avoiding zombie processes SIGCHLD signal waitpid( ) wait( ) $ (dollar sign) $? variable dollar sign ($) $? variable $ (dollar sign) $? variable dollar sign ($) $? variable blocking signals signals blocking processes signals blocking locking blocking signals POSIX module blocking signals sigprocmask syscall $ (dollar sign) $$ variable dollar sign ($) $$ variable processes timing out operations timing out operations date and time values timing out operations SIGALRM signal alarm( ) signals turning into fatal errors errors turning signals into processes signals turning into errors sigtrap pragma sigrand program named pipes sigrand program random email signatures email random signatures signatures, randomized daemon servers sockets stream sockets domains for sockets Internet domain sockets Unix domain sockets sockets Unix domain protocols socket sockets protocol associated with SOCK_ constants PF_ constants getprotobyname( ) socket( ) sockaddr_in( ) sockaddr_un( ) inet_ntoa( ) IP addresses packed, converting to ASCII strings sockets TCP protocol writing clients TCP protocol writing clients for clients TCP IO::Socket module IO::Socket::INET class INADDR_ANY sockets TCP protocol writing servers TCP protocol writing servers for servers TCP, writing accept( ) sockets non-blocking TCP protocol communicating over sockets TCP protocol communicating over send( ), communicating over TCP recv( ), TCP, communicating over IO::Socket module TCP, communicating over select( ) determining whether data can be read or written reading and writing determining whether data can be read or written buffered input/output socket programming and I/O operations buffering Nagle Algorithm TCP_NODELAY socket option select( ) reading from multiple filehandles clients UDP, setting up sockets UDP protocol writing clients for UDP (User Datagram Protocol) writing clients for IO::Socket module UDP clients/servers datagram sockets sockaddr_in( ) servers UDP, setting up sockets UDP protocol writing servers for UDP (User Datagram Protocol) writing servers for User Datagram Protocol UDP Unix domain sockets sockets Unix domain sockaddr_un( ) Unix domain sockets IO::Socket::UNIX module sockets identifying machine at end IP addresses identifying socket ends hostnames identifying at socket end gethostbyaddr( ) gethostbyname( ) sockets finding own name and address hostnames obtaining your own IP addresses determining your own Sys::Hostname module uname( ) POSIX::uname( ) fork( ) closing sockets after sockets closing after forking shutdown( ) IO::Socket module closing socket after forking clients bidirectional bidirectional clients sockets bidirectional clients servers forking fork( ) forking servers sockets forking servers stream sockets servers preforking fork( ) preforking servers sockets preforking servers servers non-forking fork( ) non-forking servers sockets non-forking servers servers multitasking, writing processes multitasking servers, writing threads.pm servers multitasking, writing with POE processes multitasking servers, writing with POE POE framework, writing multitasking server with POE::Component::Server::TCP module servers multihomed multihomed servers sockets multihomed servers IP addresses multihomed servers INADDR_ANY getsockname( ) getpeername( ) daemon servers sockets daemon servers servers daemon servers POSIX::setsid( ) restarting servers on demand sockets restarting servers on demand servers restarting on demand SIGHUP signal input managing multiple streams sockets managing multiple input streams IO::Multiplex module mux_input( ) accept( ) IO::Multiplex module backsniff program sockets logging port connection attempts port connection attempts, logging logging port connection attempts Sys::Syslog module getsockname( ) getpeername( ) fwdport program firewalls, fetching web pages through security connecting through firewalls sockets connecting through firewalls Internet services protocols Internet Internet protocols Internet services remote procedure calls XML-RPC XMLRPC::Lite module SOAP (Simple Object Access Protocol) Simple Object Access Protocol SOAP REST (Representational State Transfer) Representational State Transfer (REST) DNS lookups Internet services DNS lookups IP addresses DNS lookups gethostbyname( ) finding IP addresses inet_ntoa( ) Net::DNS module clients FTP Internet services FTP client FTP clients Net::FTP module email sending Internet services mail email Mail::Mailer module sendmail program MUAs (Mail User Agents) SMTP (Simple Mail Transfer Protocol) Mail User Agents (MUAs) Simple Mail Transfer Protocol (SMTP) Usenet news messages Internet services Usenet news posting Usenet messages reading Usenet messages Net::NNTP module group( ), Usenet news messages servers POP3 POP3 servers email reading with POP3 Net::POP3 module POP (Post Office Protocol) MTA (Mail Transport Agent) Mail Transport Agent (MTA) Post Office Protocol POP login( ), POP3 server POP (Post Office Protocol) servers logging in servers POP programs simulating telnet from telnet, simulating from programs Internet services simulating telnet connection Net::Telnet module Internet services pinging machines pinging machines Net::Ping module LDAP (Lightweight Directory Access Protocol) server Internet services accessing LDAP server servers LDAP LDAP (Lightweight Directory Access Protocol) Lightweight Directory Access Protocol LDAP Net::LDAP module connect( ), LDAP server bind( ), LDAP server Distinguished Name (DN) DN (Distinguished Name) Authen::SASL module search( ), LDAP server LDAP (Lightweight Directory Access Protocol) server search( ) and servers LDAP search( ) modify( ), LDAP server LDAP (Lightweight Directory Access Protocol) server modify( ) and servers LDAP email attachments sending MIME::Lite module attach( ) MIME (Multimedia Internet Mail Extensions) Multimedia Internet Mail Extensions MIME Net::SMTP module print( ) email attachments email attachments extracting MIME-Tools module MIME (Multimedia Internet Mail Extensions) XML-RPC server Internet services XML-RPC server web services XML-RPC server SOAP::Lite module XML-RPC client Internet services XML-RPC client XMLRPC::Lite module methods remote Internet services SOAP server SOAP (Simple Object Access Protocol) server web services SOAP server servers SOAP SOAP::Lite module Internet services SOAP client SOAP (Simple Object Access Protocol) client web services SOAP client rfrm program POP (Post Office Protocol) servers fetching and summarizing messages servers POP fetching and summarizing messages POP (Post Office Protocol) servers POP3 servers also POP3 servers IP addresses expn and vrfy programs expn program vrfy program Internet services expn and vrfy programs Net::SMTP module expn and vrfy programs EXPN command VRFY command SMTP (Simple Mail Transfer Protocol) server servers SMTP Net::DNS module $ (dollar sign) $0 variable dollar sign ($) $0 variable CGI programming web architecture URLs (Uniform Resource Locators) Uniform Resource Locators URLs schemes, URLs CGI.pm module GET request methods HTTP CGI programming HTTP methods HTTP methods HEAD method POST method idempotency error log, web server access log, web server errors CGI scripts debugging CGI scripts security CGI scripts CGI programming security and HTML forms forms, HTML web, references on CGI programming writing scripts scripts, CGI CGI programming programs CGI CGI programming methods HTTP CGI programming HTTP methods HTTP methods GET request POST method CGI.pm module writing CGI scripts input from HTML forms [input HTML forms CGI programming param( ) CGI programming form parameters CGI programming redirecting error messages errors CGI scripts redirecting messages from CGI::Carp module errors CGI scripts fixing 500 server in CGI programming fixing 500 server errors permissions CGI scripts debugging CGI scripts permissions libraries libraries permissions CGI::Carp module security CGI scripts CGI programming security and taint mode race conditions CGI programming security and executing user commands security CGI scripts executing user commands input executing shell commands from shell escapes, executing commands without system( ) shell escapes fork( ) shell escapes exec( ) shell escapes backtick (`) executing commands without shell escapes ` (backtick) executing commands without shell escapes lists formatting with HTML shortcuts tables, formatting with HTML shortcuts HTML shortcuts, formatting lists and tables with CGI.pm module HTML helper functions database access SQL queries browsers redirecting with CGI CGI programming redirecting browsers redirect( ) switch statement CGI programming debugging raw HTTP exchange debugging raw HTTP exchange cookies CGI CGI programming cookies CGI.pm module managing cookies HTML forms sticky widgets forms, HTML sticky widgets sticky widgets, creating CGI programming sticky widgets creating sticky widgets CGI.pm module creating sticky widgets CGI programming multiscreen scripts user interfaces multiscreen CGI scripts shopping cart applications applications shopping cart CGI programming shopping cart application, developing hidden( ), generating sticky hidden fields switch statement HTML forms saving and mailing forms, HTML saving and emailing email sending HTML forms via CGI programming saving and mailing HTML forms save_parameters( ), HTML forms save( ), HTML forms CGI programming form parameters chemiserie program CGI programming chemiserie program web automation libwww-perl modules LWP modules URLs (Uniform Resource Locators) fetching from Perl scripts web automation fetching URLs fetching URLs from Perl scripts LWP::Simple module get( ), fetching URLs from Perl scripts LWP::UserAgent module HTTP::Response module URI::Heuristic module HTML forms automating submission web automation HTML forms, submitting forms, HTML submitting LWP::UserAgent module automating HTML forms POST method LWP::Simple module automating HTML forms query_form( ) URI::Escape module uri_escape( ) proxy, submitting forms through HTML extracting URLs from URLs (Uniform Resource Locators) extracting from HTML web automation extracting URLs from HTML hyperlinks extracting from HTML HTML::LinkExtor module links( ), extracting URLs hyperlinks clearing link list links hyperlinks web automation converting ASCII to and from HTML converting ASCII to and from HTML HTML converting ASCII to and from characters converting ASCII to and from HTML strings converting ASCII to and from HTML HTML::TextToHTML module ASCII (American Standard Code for Information Interchange) converting HTML to converting HTML to ASCII HTML::FormatText module format_string( ) web automation HTML removing or extracting tags HTML extracting tags deleting HTML tags from strings strings removing or extracting HTML tags LWP modules extracting HTML tags parsing HTML tags tags, HTML HTML nested HTML tags HTML finding stale or fresh links web automation finding stale or fresh links hyperlinks finding stale or fresh head( ), finding stale hyperlinks LWP::Simple module finding stale hyperlinks URI::Heuristic module web pages modified, links in finding fresh hyperlinks surl script web automation HTML templates HTML templates templates HTML template( ) Text::Template module SQL database database access SQL web automation mirroring web pages LWP::Simple module mirroring web pages mirror( ) If-Modified-Since header web automation robots robots for Web traversal navigating Web with robots creating robots for Web traversal LWP::RobotUA module parsing web server log file log files web server web automation server logs parsing web servers logs parsing access log, web server Apache web server log files Common Log Format standard web servers log files, Common Log Format servers web common log format fields web servers logs processing log files web server processing web automation server logs processing errors web server error log Logfile::Apache module report( ), processing server logs logging server logs, processing servers processing logs web automation using cookies cookies web automation and LWP::UserAgent module using cookies log files logging also logging cookie_jar( ) HTTP::Cookies module web automation fetching password-protected pages web pages password-protected authentication fetching password-protected web pages credentials( ) authentication realms security fetching secure web pages web automation fetching https:// web pages web pages https:// SSL (Secure Sockets Layer) Secure Sockets Layer (SSL) Crypt::SSLeay module IO::Socket::SSL module OpenSSL libraries libraries OpenSSL GET request resuming web automation resuming HTTP GET files downloading, resuming HTTP GET GET request using HTTP 1.1 Range header Range header HTML parsing web automation HTML parsing parsing HTML regular expressions parsing HTML HTML::TokeParser module get_token( ), parsing HTML web automation extracting table data HTML tables in, extracting data from converting HTML tables into Perl data structures HTML::TableContentParser module parse( ), HTML tables, extracting data htmlsub program web automation htmlsub program HTML text substitutions web automation HTML text substitutions strings HTML text substitutions hrefsub program HREF fields, substitutions for mod_perl Apache web server mod_perl also mod_perl CGI programming performance mod_perl also mod_perl CGI programming performance Apache::Registry module Apache::PerlRun module Apache web server handlers, writing handlers Apache code handlers handlers Apache web server phases of request-response transaction mod_perl documentation modules mod_perl mod_perl 2 mod_perl authentication authentication with mod_perl cookies setting in mod_perl mod_perl cookies setting Apache::Cookie module bake( ) CGI::Cookie module mod_perl cookies accessing values cookies accessing values with mod_perl Apache::Cookie module accessing values CGI::Cookie module accessing values mod_perl redirecting browsers browsers redirecting with mod_perl external redirection URLs (Uniform Resource Locators) external redirection internal redirection Apache web server internal redirection mod_perl interrogating headers headers, interrogating with mod_perl mod_perl accessing form parameters HTML forms accessing parameters with mod_perl Apache::Request module accessing form parameters files uploaded, receiving with mod_perl handler mod_perl Apache handlers receiving uploaded files Apache::Request module receiving uploaded files mod_perl speeding database access database access speeding up with mod_perl performance database access, speeding with mod_perl Apache::DBI module Apache web server logging requests, customizing customizing Apache logging requests logging customizing Apache logging requests mod_perl Apache logging requests, customizing Apache::Traffic module Apache::DBILogger module mod_perl URLs, transparently storing information in URLs (Uniform Resource Locators) transparently storing information in pnotes URLs, storing information in mod_perl communicating with PHP PHP, communicating with mod_perl communicating between mod_perl and PHP Apache web server notes notes, Apache requests CGI programming improving efficiency of performance web server, improving CGI programming migrating to mod_perl mod_perl migrating from CGI web servers performance, improving servers web performance, improving Apache::Registry module migrating from CGI to mod_perl Apache::PerlRun module migrating from CGI to mod_perl handlers sharing information between mod_perl Apache handlers sharing information between Apache web server pnotes, sharing information between handlers pnotes Apache requests, sharing information between handlers mod_perl reloading changed modules modules loading reloading changed modules with mod_perl loading modules with mod_perl Apache::StatINC module Apache::Reload module mod_perl applications, benchmarking benchmarking mod_perl applications applications mod_perl, benchmarking Apache::Timeit module Apache::DProf module HTML::Mason module mod_perl templating with HTML::Mason templates HTML::Mason HTML::Mason module configuration mod_perl templating with HTML::Mason configuration templates HTML::Mason configuration HTML::Mason module Mason syntax mod_perl templating with HTML::Mason Mason syntax templates HTML::Mason Mason syntax HTML::Mason module objects mod_perl templating with HTML::Mason objects templates HTML::Mason objects HTML::Mason module autohandlers mod_perl templating with HTML::Mason autohandlers templates HTML::Mason autohandlers HTML::Mason module dhandlers mod_perl templating with HTML::Mason dhandlers templates HTML::Mason dhandlers HTML::Mason module dhandlers Apache::Template module Template Toolkit Template Toolkit mod_perl templating with Template Toolkit templates Template Toolkit Template Toolkit configuration mod_perl templating with Template Toolkit configuration templates Template Toolkit configuration Template Toolkit syntax mod_perl templating with Template Toolkit syntax templates Template Toolkit syntax Template Toolkit Perl code mod_perl templating with Template Toolkit Perl code templates Template Toolkit Perl code Template Toolkit data structures mod_perl templating with Template Toolkit data structures templates Template Toolkit data structures Template Toolkit subroutines mod_perl templating with Template Toolkit subroutines templates Template Toolkit subroutines Template Toolkit other templates mod_perl templating with Template Toolkit other templates templates Template Toolkit other templates Template Toolkit parameters mod_perl templating with Template Toolkit parameters templates Template Toolkit parameters Template Toolkit plug-ins mod_perl templating with Template Toolkit plug-ins templates Template Toolkit plug-ins XML (Extensible Markup Language) Extensible Markup Language XML SGML (Standard Generalized Markup Language) Standard Generalized Markup Language (SGML) XML (Extensible Markup Language) reasons for success of text XML as HTML XML and XML (Extensible Markup Language) syntax XML (Extensible Markup Language) declaration encoding attribute, XML portability encodings in XML Unicode encodings, XML and XML declaration XML (Extensible Markup Language) Unicode encodings processes XML processing instructions XML (Extensible Markup Language) processing instructions comments XML XML (Extensible Markup Language) comments CDATA, XML XML (Extensible Markup Language) CDATA XML (Extensible Markup Language) well-formed documents XML (Extensible Markup Language) schemas schemas, XML World Wide Web Consortium (W3C) W3C (World Wide Web Consortium) XML Schema OASIS group RelaxNG schema XML (Extensible Markup Language) validating documents against schemas XML documents validating against schemas XML (Extensible Markup Language) namespaces namespaces, XML nested elements, XML XML (Extensible Markup Language) nested elements XSLT (XML Stylesheet Language for Transformations) XML Stylesheet Language for Transformations XSLT XML (Extensible Markup Language) transformations transformations, XML XML::LibXSLT module XML::Sablotron module, XSLT XML::XSLT module XML (Extensible Markup Language) paths paths, XML XPath XML (Extensible Markup Language) Perl and, history of XML::Parser module caution against using directly XML::SAX modules, parsing XML Document Object Model (DOM) DOM (Document Object Model) XML::LibXML module libxml2 library libraries libxml2 DOM (Document Object Model) trees XML (Extensible Markup Language) parsing into data structures parsing XML into data structures data structures parsing XML into XML::Simple module ForceArray option XMLin( ) XML (Extensible Markup Language) parsing into DOM tree parsing XML into DOM tree DOM (Document Object Model) trees parsing XML into XML::LibXML module parsing XML into a DOM tree getElementsByTagName( ) returning a list of elements by nodes createTextNode( ) createElement( ) appendChild( ) toString( ), XML documents parsing XML into SAX events SAX (Simple API for XML) events, parsing XML into XML (Extensible Markup Language) parsing into SAX events Simple API for XML (SAX) SAX (Simple API for XML) memory event-based XML parsing performance event-based XML parsing XML::SAX module parsing XML into SAX events XML::Parser module XML::LibXML module XML::SAX::PurePerl module XML::SAX module XML::SAX::ParserFactory module XML::SAX::Base module methods XML::SAX::Base XML (Extensible Markup Language) filtering filtering XML XML documents changing elements or text XML::SAX::Machines module, filtering XML XML (Extensible Markup Language) validating XML::LibXML module validating XML against DTD XML::Xerces module, validating XML against W3C Schema libxml2 library validation( ) libraries libxml2 DOM (Document Object Model) trees building while validating XML XML documents finding elements and text finding text and elements in XML documents XML::LibXML module finding elements and text in XML documents findnodes( ) vs. getElementsByTagName( ) getElementsByTagName( ) vs. findnodes( ) XPath expressions XML (Extensible Markup Language) documents XML documents XSLT (XML Stylesheet Language for Transformations) processing processes XSLT, processing XML::LibXSLT module output_file( ) output_fh( ) register_function( ) get_request( ) XML (Extensible Markup Language) files, larger than available memory, processing files XML, larger than available memory, processing processes large XML files, processing XML::Twig module, processing large XML files files RSS, reading and writing RSS (Rich Site Summary) files, reading and writing reading and writing RSS files RSS (Rich Site Summary) Rich Site Summary RSS XML::RSS module XML (Extensible Markup Language) writing writing XML XML::Simple module writing XML XMLout( ), writing XML