# Rex Swain's HTMLified
Perl 5 Reference Guide

Last updated 22 March 2001
[Links updated 7 September 2003]

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This is an HTMLified version of the Perl 5 Desktop Reference, ISBN 1-56592-187-9, copyright © 1996 by Johan Vromans. HTML copyright © 1996-2000 by Rex Swain.

See Perl 5 Desktop Reference for information about ordering a printed copy ($6.95) of the booklet from O'Reilly. [But it's no longer in print -- instead, get the Perl 5 Pocket Reference, 2nd Edition, updated for Perl version 5.005.] [Now there is a 3rd Edition, revised to cover Perl version 5.6.] [Now there is a 4th Edition, revised to cover Perl version 5.8.]

See The Perl Reference Guide for links to other online versions in various formats (PostScript, PDF, etc.).

For more detail, see Perl Documentation or Alphabetical Listing of Perl Functions.

## Contents

Conventions
Command-Line Options Literals Variables Operators Statements Subroutines, Packages and Modules Object-Oriented Programming Arithmetic Functions Conversion Functions Structure Conversion String Functions Array and List Functions Regular Expressions Search and Replace Functions | File Test Operators File Operations Input / Output Formats Directory Reading Routines System Interaction Networking System V IPC Miscellaneous Information from System Files Special Variables Special Arrays Environment Variables The Perl Debugger

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## Index

abs accept alarm and ARGV ArithmeticFunctions ArrayListFunctions ArraysSpecial atan2 BEGIN bind binmode bless caller chdir chmod chomp chop chr chroot close closedir cmp CommandLineOptions connect Contents continue Conventions ConversionFunctions ConversionStructure cos crypt dbmclose dbmopen Debugger defined delete die DirectoryReadingRoutines do do do dump each else elsif END ENV EnvironmentVariables eof eq eval eval exec exists exit exp EXPORT EXPORT_OK ExpressionsRegular fcntl fileno FileOperations FilesSystemInformationFrom FileTestOperators flock for foreach fork Formats formline FunctionsArithmetic FunctionsArrayList FunctionsConversion FunctionsSearchReplace FunctionsString ge getc getlogin getpeername getpgrp getppid getpriority getsockname getsockopt glob gmtime goto goto grep gt hex HOME if import INC Index index InformationFromSystemFiles InputOutput int InteractionSystem ioctl ISA join keys kill last lc lcfirst le length link ListArrayFunctions listen Literals local localtime log LOGDIR lstat lt m map Miscellaeous mkdir Modules my ne Networking next no npt ObjectOrientedProgramming oct open opendir OperationsFile Operators OperatorsFileTest OptionsCommandLine or ord OutputInput OVERLOAD pack package Packages PATH PERL5DB PERL5LIB PERLLIB pipe pop pos print printf push quotemeta rand read readdir ReadingDirectoryRoutines readlink recv redo ref RegularExpressions rename ReplaceSearchFunctions require reset return reverse rewindir rindex rmdir RoutinesDirectoryReading s scalar scalar SearchReplaceFunctions seek seekdir select send setpgrp setpriority setsockopt shift shutdown SIG sin sleep socket socketpair sort SpecialArrays SpecialVariables splice split sprintf sqrt srand stat Statements StringFunctions StructureConversion study sub Subroutines substr symlink syscall sysread system SystemFilesInformationFrom SystemInteraction SystemVIPC syswrite tell telldir TestFileOperators tie time times tr truncate uc ucfirst umask undef unless unlink unpack unshift untie until until use utime values Variables VariablesEnvironment VariablesSpecial vec wait waitpid wantarray warn while write xor y

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## Conventions

`fixed` | denotes literal text.
THIS | means variable text, i.e., things you must fill in.
THIS† | means that THIS will default to `$_` if omitted.
word | is a keyword, i.e., a word with a special meaning.
RETURN key | denotes pressing a keyboard key.
[...] | denotes an optional part.

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## Command-Line Options

`-a`
  turns on autosplit mode when used with `-n` or `-p`. Splits to `@F`.
`-c`
  checks syntax but does not execute.
`-d`
  runs the script under the debugger. Use `-de 0` to start the debugger without a script
`-D` NUMBER
  sets debugging flags.
`-e` COMMANDLINE
  may be used to enter a single line of script. Multiple `-e` commands may be given to build up a multiline script.
`-F` REGEXP
  specifies a regular expression to split on if `-a` is in effect.
`-i` EXT
  files processed by the `< >` construct are to be edited in place.
`-I` DIR
  with `-P`, tells the C preprocessor where to look for include files. The directory is prepended to `@INC`.
`-l` [OCTNUM]
  enables automatic line-end processing, e.g., `-l013`.
`-n`
  assumes an input loop around your script. Lines are not printed.
`-p`
  assumes an input loop around your script. Lines are printed.
`-P`
  runs the C preprocessor on the script before compilation by Perl.
`-s`
  interprets `-xxx` on the command line as a switch and sets the corresponding variable `$xxx` in the script.
`-S`
  uses the `PATH` environment variable to search for the script.
`-T`
  forces taint checking.
`-u`
  dumps core after compiling the script. To be used with the undump(1) program (where available).
`-U`
  allows perl to perform unsafe operations.
`-v`
  prints the version and patchlevel of your Perl executable.
`-w`
  prints warnings about possible spelling errors and other error-prone constructs in the script.
`-x` [DIR]
  extracts Perl program from input stream. If DIR is specified, switches to this directory before running the program.
`-0` VAL
  (that's the number zero.) Designates an initial value for the record separator `$/`. See also `-l`

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## Literals

Numeric:
  `123`
  `1_234`
  `123.4`
  `5E-10`
  `0xff` (hex)
  `0377` (octal)
String:

`'abc'`
  literal string, no variable interpolation or escape characters, except `\'` and `\\`. Also: `q/abc/`. Almost any pair of delimiters can be used instead of `/`...`/`.
`"abc"`
  Variables are interpolated and escape sequences are processed. Also: `qq/abc/`.
  Escape sequences: `\t` (Tab), `\n` (Newline), `\r` (Return), `\f` (Formfeed), `\b` (Backspace), `\a` (Alarm), `\e` (Escape), `\033` (octal), `\x1b` (hex), `\c[` (control)
  `\l` and `\u` lowercase/uppercase the following character. `\L` and `\U` lowercase/uppercase until a `\E` is encountered. `\Q` quote regular expression characters until a `\E` is encountered.
```COMMAND```
  evaluates to the output of the COMMAND. Also: `qx/`COMMAND`/`.

Array:
  `(1, 2, 3)`. `()` is an empty array.
  `(1..4)` is the same as `(1,2,3,4)`,
  likewise `('a'..'z')`.
  `qw/foo bar` ...`/` is the same as `('foo','bar',`...`)`.
Array reference:
  `[1,2,3]`
Hash (associative array):
  `(`KEY1`,` VAL1`,` KEY2`,` VAL2`,`...`)`
  Also `(`KEY1`=>` VAL1`,` KEY2`=>` VAL2`,`...`)`
Hash reference:
  `{`KEY1`,` VAL1`,` KEY2`,` VAL2`,`...`}`
Code reference:
  sub `{`STATEMENTS`}`
Filehandles:
  `<STDIN>`, `<STDOUT>`, `<STDERR>`, `<ARGV>`, `<DATA>`.
  User-specified: HANDLE, `$`VAR.
Globs:
  `<`PATTERN`>` evaluates to all filenames according to the pattern. Use `<${`VAR`}>` or glob `$`VAR to glob from a variable.
Here-Is:
  `<<`IDENTIFIER
  Shell-style "here document."
Special tokens:
  `__FILE__`: filename; `__LINE__`: line number; `__END__`: end of program; remaining lines can be read using the filehandle `DATA`.

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## Variables

`$var` | a simple scalar variable.
`$var[28]` | 29th element of array `@var`.
`$p = \@var` | now `$p` is a reference to array `@var`.
`$$p[28]` | 29th element of array referenced by `$p`. Also, `$p->[28]`.
`$var[-1]` | last element of array `@var`.
`$var[$i][$j]` | `$j`th element of the `$i`th element of array `@var`.
`$var{'Feb'}` | one value from hash (associative array) `%var`.
`$p = \%var` | now `$p` is a reference to hash `%var`.
`$$p{'Feb'}` | a value from hash referenced by `$p`. Also, `$p->{'Feb'}`.
`$#var` | last index of array `@var`.
`@var` | the entire array; in a scalar context, the number of elements in the array.
`@var[3,4,5]` | a slice of array `@var`.
`@var{'a','b'}` | a slice of `%var`; same as `($var{'a'},$var{'b'})`.
`%var` | the entire hash; in a scalar context, true if the hash has elements.
`$var{'a',1,`...`}` | emulates a multidimensional array.
`('a'`...`'z')[4,7,9]` | a slice of an array literal.
PKG`::`VAR | a variable from a package, e.g., `$pkg::var`, `@pkg::ary`.
`\`OBJECT | reference to an object, e.g., `\$var`, `\%hash`.
`*`NAME | refers to all objects represented by NAME. `*n1 = *n2` makes `n1` an alias for `n2`. `*n1 = $n2` makes `$n1` an alias for `$n2`.

You can always use a `{`BLOCK`}` returning the right type of reference instead of the variable identifier, e.g., `${`...`}`, `&{`...`}`. `$$p` is just a shorthand for `${$p}`.

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## Operators

`**` |  | Exponentiation
`+ -` | `* /` | Addition, subtraction, multiplication, division
`%` |  | Modulo division
`& |` | `^` | Bitwise AND, bitwise OR, bitwise exclusive OR
`>>` | `<<` | Bitwise shift right, bitwise shift left
`||` | `&&` | Logical OR, logical AND
`.` |  | Concatenation of two strings
`x` |  | Returns a string or array consisting of the left operand (an array or a string) repeated the number of times specified by the right operand
All of the above operators also have an assignment operator, e.g., `.=`
`->` |  | Dereference operator
`\` |  | Reference (unary)
`!` | `~` | Negation (unary), bitwise complement (unary)
`++` | `--` | Auto-increment (magical on strings), auto-decrement
`==` | `!=` | Numeric equality, inequality
`eq` | `ne` | String equality, inequality
`<` | `>` | Numeric less than, greater than
`lt` | `gt` | String less than, greater than
`<=` | `>=` | Numeric less (greater) than or equal to
`le` | `ge` | String less (greater) than or equal to
`<=>` | `cmp` | Numeric (string) compare. Returns -1, 0, 1.
`=~` | `!~` | Search pattern, substitution, or translation (negated)
`..` |  | Range (scalar context) or enumeration (array context)
`?:` |  | Alternation (if-then-else) operator
`,` |  | Comma operator, also list element separator. You can also use `=>`.
`not` |  | Low-precedence negation
`and` |  | Low-precedence AND
`or` | `xor` | Low-precedence OR, exclusive OR

All Perl functions can be used as list operators, in which case they have very high or very low precedence, depending on whether you look at the left or the right side of the operator. Only the operators not, and, or and xor have lower precedence.

A "list" is a list of expressions, variables, or lists. An array variable or an array slice may always be used instead of a list.

Parentheses can be added around the parameter lists to avoid precedence problems.

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## Statements

Every statement is an expression, optionally followed by a modifier, and terminated by a semicolon. The semicolon may be omitted if the statement is the final one in a BLOCK.

Execution of expressions can depend on other expressions using one of the modifiers if, unless, while or until, for example:

EXPR1 if EXPR2 `;`
EXPR1 until EXPR2 `;`

The logical operators `||`, `&&` or `?:` also allow conditional execution:

EXPR1 `||` EXPR2 `;`
EXPR1 `?` EXPR2 `:` EXPR3 `;`

Statements can be combined to form a BLOCK when enclosed in `{}`. Blocks may be used to control flow:

if `(`EXPR`)` BLOCK [ [ elsif `(`EXPR`)` BLOCK ... ] else BLOCK ]
unless `(`EXPR`)` BLOCK [ else BLOCK ]
[ LABEL`:` ] while (EXPR) BLOCK [ continue BLOCK ]
[ LABEL`:` ] until (EXPR) BLOCK [ continue BLOCK ]
[ LABEL`:` ] for (EXPR`;` EXPR`;` EXPR) BLOCK
[ LABEL`:` ] foreach VAR† (LIST) BLOCK
[ LABEL`:` ] BLOCK [ continue BLOCK ]

Program flow can be controlled with:

goto LABEL | Continue execution at the specified label.
last [ LABEL ] | Immediately exits the loop in question. Skips continue block.
next [ LABEL ] | Starts the next iteration of the loop.
redo [ LABEL ] | Restarts the loop block without evaluating the conditional again.

Special forms are:

do BLOCK while EXPR `;`
do BLOCK until EXPR `;`

which are guaranteed to perform BLOCK once before testing EXPR, and

do BLOCK

which effectively turns BLOCK into an expression.

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## Subroutines, Packages and Modules

`&`SUBROUTINE LIST
  Executes a SUBROUTINE declared by a sub declaration, and returns the value of the last expression evaluated in SUBROUTINE. SUBROUTINE can be an expression yielding a reference to a code object. The `&` may be omitted if the subroutine has been declared before being used.
bless REF [ `,` PACKAGE ]
  Turns the object REF into an object in PACKAGE. Returns the reference.
caller [ EXPR ]
  Returns an array (`$`package,`$`file,`$`line,...) for a specific subroutine call. `caller` returns this info for the current subroutine, `caller(1)` for the caller of this subroutine, etc. Returns false if no caller.
do SUBROUTINE LIST
  Deprecated form of `&`SUBROUTINE.
goto `&`SUBROUTINE
  Substitutes a call to SUBROUTINE for the current subroutine.
import MODULE [ [ VERSION ] LIST ]
  Imports the named subroutines from MODULE.
no MODULE [ LIST ]
  Cancels imported semantics. See use.
package NAME
  Designates the remainder of the current block as a package.
require EXPR†
  If EXPR is numeric, requires Perl to be at least that version. Otherwise EXPR must be the name of a file that is included from the Perl library. Does not include more than once, and yields a fatal error if the file does not evaluate to a true value. If EXPR is a bare word, assumes extension `.pm` for the name of the file.
return EXPR
  Returns from a subroutine with the value specified.
sub NAME `{` EXPR `;` ... `}`
  Designates NAME as a subroutine. Parameters are passed by reference as array `@_`. Returns the value of the last expression evaluated.
[ sub ] `BEGIN` `{` EXPR `;` ... `}`
  Defines a setup BLOCK to be called before execution.
[ sub ] `END` `{` EXPR `;` ... `}`
  Defines a cleanup BLOCK to be called upon termination.
tie VAR`,` PACKAGE`,` [ LIST ]
  Ties a variable to a package that will handle it. Can be used to bind a dbm or ndbm file to a hash.
untie VAR
  Breaks the binding between the variable and the package.
use MODULE [ [ VERSION ] LIST ]
  Imports semantics from the named module into the current package.

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## Object-Oriented Programming

Perl rules of object oriented programming:

- An object is simply a reference that happens to know which class it belongs to. Objects are blessed, references are not.
- A class is simply a package that happens to provide methods to deal with object references. If a package fails to provide a method, the base classes as listed in `@ISA` are searched.
- A method is simply a subroutine that expects an object reference (or a package name, for static methods) as the first argument.

Methods can be applied with:

METHOD OBJREF PARAMETERS or
OBJREF`->`METHOD PARAMETERS

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## Arithmetic Functions

abs EXPR† | Returns the absolute value of its operand.
atan2 Y`,`X | Returns the arctangent of Y/X in the range -pi to pi.
cos EXPR† | Returns the cosine of EXPR (expressed in radians).
exp EXPR† | Returns `e` to the power of EXPR.
int EXPR† | Returns the integer portion of EXPR.
log EXPR† | Returns natural logarithm (base `e`) of EXPR.
rand [ EXPR ] | Returns a random fractional number between 0 and the value of EXPR. If EXPR is omitted, returns a value between 0 and 1.
sin EXPR† | Returns the sine of EXPR (expressed in radians).
sqrt EXPR† | Returns the square root of EXPR.
srand [ EXPR ] | Sets the random number seed for the rand operator.
time | Returns the number of seconds since January 1, 1970. Suitable for feeding to gmtime and localtime.

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## Conversion Functions

chr EXPR†
  Returns the character represented by the decimal value EXPR.
gmtime EXPR†
  Converts a time as returned by the time function to a 9-element array (0: `$`sec, 1: `$`min, 2: `$`hour, 3: `$`mday, 4: `$`mon, 5: `$`year, 6: `$`wday, 7: `$`yday, 8: `$`isdst) with the time analyzed for the Greenwich time zone. `$`mon has the range 0..11 and `$`wday has the range 0..6.
hex EXPR†
  Returns the decimal value of EXPR interpreted as a hex string.
localtime EXPR†
  Converts a time as returned by the time function to ctime(3) string. In array context, returns a 9-element array with the time analyzed for the local time zone.
oct EXPR†
  Returns the decimal value of EXPR interpreted as an octal string. If EXPR starts off with `0x`, interprets it as a hex string instead.
ord EXPR†
  Returns the ASCII value of the first character of EXPR.
vec EXPR`,` OFFSET`,` BITS
  Treats string EXPR as a vector of unsigned integers, and yields the bit at OFFSET. BITS must be between 1 and 32. May be assigned to.

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## Structure Conversion

pack TEMPLATE`,` LIST
  Packs the values into a binary structure using TEMPLATE.
unpack TEMPLATE`,` EXPR
  Unpacks the structure EXPR into an array, using TEMPLATE.

TEMPLATE is a sequence of characters as follows:

`a` / `A` | ASCII string, null- / space-padded
`b` / `B` | Bit string in ascending / descending order
`c` / `C` | Native / unsigned char value
`f` / `d` | Single / double float in native format
`h` / `H` | Hex string, low / high nybble first
`i` / `I` | Signed / unsigned integer value
`l` / `L` | Signed / unsigned long value
`n` / `N` | Short / long in network (big endian) byte order
`s` / `S` | Signed / unsigned short value
`u` / `P` | Uuencoded string / pointer to a string
`v` / `V` | Short / long in VAX (little endian) byte order
`x` / `@` | Null byte / null fill until position
`X` | Backup a byte

Each character may be followed by a decimal number that will be used as a repeat count; an asterisk (`*`) specifies all remaining arguments. If the format is preceded with `%`N, unpack returns an N-bit checksum instead. Spaces may be included in the template for readability purposes.

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## String Functions

chomp LIST†
  Removes line endings from all elements of the list; returns the (total) number of characters removed.
chop LIST†
  Chops off the last character on all elements of the list; returns the last chopped character.
crypt PLAINTEXT`,` SALT
  Encrypts a string.
eval EXPR†
  EXPR is parsed and executed as if it were a Perl program. The value returned is the value of the last expression evaluated. If there is a syntax error or runtime error, an undefined string is returned by eval, and `$@` is set to the error message. See also eval in section Miscellaneous.
index STR`,` SUBSTR [ `,` OFFSET ]
  Returns the position of SUBSTR in STR at or after OFFSET. If the substring is not found, returns `-1` (but see `$[` in section Special Variables).
length EXPR†
  Returns the length in characters of the value of EXPR.
lc EXPR
  Returns a lowercase version of EXPR.
lcfirst EXPR
  Returns EXPR with the first character lowercase.
quotemeta EXPR
  Returns EXPR with all regular expression metacharacters quoted.
rindex STR`,` SUBSTR [ `,` OFFSET ]
  Returns the position of the last SUBSTR in STR at or before OFFSET.
substr EXPR`,` OFFSET [ `,` LEN ]
  Extracts a substring of length LEN out of EXPR and returns it. If OFFSET is negative, counts from the end of the string. May be assigned to.
uc EXPR
  Returns an uppercased version of EXPR.
ucfirst EXPR
  Returns EXPR with the first character uppercased.

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## Array and List Functions

delete `$`HASH`{`KEY`}`
  Deletes the specified value from the specified hash. Returns the deleted value unless HASH is tied to a package that does not support this.
each `%`HASH
  Returns a 2-element array consisting of the key and value for the next value of the hash. Entries are returned in an apparently random order. After all values of the hash have been returned, a null array is returned. The next call to each after that will start iterating again.
exists EXPR†
  Checks if the specified hash key exists in its hash array.
grep EXPR`,` LIST
grep BLOCK LIST
  Evaluates EXPR or BLOCK for each element of the LIST, locally setting `$_` to refer to the element. Modifying `$_` will modify the corresponding element from LIST. Returns the array of elements from LIST for which EXPR returned true.
join EXPR`,` LIST
  Joins the separate strings of LIST into a single string with fields separated by the value of EXPR, and returns the string.
keys `%`HASH
  Returns an array with all of the keys of the named hash.
map EXPR`,` LIST
map BLOCK LIST
  Evaluates EXPR or BLOCK for each element of the LIST, locally setting `$_` to refer to the element. Modifying `$_` will modify the corresponding element from LIST. Returns the list of results.
pop `@`ARRAY
  Pops off and returns the last value of the array.
push `@`ARRAY`,` LIST
  Pushes the values of LIST onto the end of the array.
reverse LIST
  In array context, returns the LIST in reverse order. In scalar context: returns the first element of LIST with bytes reversed.
scalar `@`ARRAY
  Returns the number of elements in the array.
scalar `%`HASH
  Returns a true value if the hash has elements defined.
shift [ `@`ARRAY ]
  Shifts the first value of the array off and returns it, shortening the array by 1 and moving everything down. If `@`ARRAY is omitted, shifts `@ARGV` in main and `@_` in subroutines.
sort [ SUBROUTINE ] LIST
  Sorts the LIST and returns the sorted array value. SUBROUTINE, if specified, must return less than zero, zero, or greater than zero, depending on how the elements of the array (available to the routine as `$a` and `$b`) are to be ordered. SUBROUTINE may be the name of a user-defined routine, or a BLOCK.
splice `@`ARRAY`,` OFFSET [ `,` LENGTH [ `,` LIST ] ]
  Removes the elements of `@`ARRAY designated by OFFSET and LENGTH, and replaces them with LIST (if specified). Returns the elements removed.
split [ PATTERN [ `,` EXPR† [ `,` LIMIT ] ] ]
  Splits a string into an array of strings, and returns it. If LIMIT is specified, splits into at most that number of fields. If PATTERN is also omitted, splits at the whitespace. If not in array context, returns number of fields and splits to `@_`. See also Search and Replace Functions.
unshift `@`ARRAY`,` LIST
  Prepends list to the front of the array, and returns the number of elements in the new array.
values `%`HASH
  Returns a normal array consisting of all the values of the named hash.

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## Regular Expressions

Each character matches itself, unless it is one of the special characters `+ ? . * ^ $ ( ) [ ] { } | \`. The special meaning of these characters can be escaped using a `\`.

`.` | matches an arbitrary character, but not a newline unless it is a single-line match (see m//s).
`(`...`)` | groups a series of pattern elements to a single element.
`^` | matches the beginning of the target. In multiline mode (see m//m) also matches after every newline character.
`$` | matches the end of the line. In multiline mode also matches before every newline character.
`[` ... `]` | denotes a class of characters to match. `[^` ... `]` negates the class.
`(` ... `|` ... `|` ... `)` | matches one of the alternatives.
`(?#` TEXT `)` | Comment.
`(?:` REGEXP `)` | Like `(`REGEXP`)` but does not make back-references.
`(?=` REGEXP `)` | Zero width positive look-ahead assertion.
`(?!` REGEXP `)` | Zero width negative look-ahead assertion.
`(?` MODIFIER `)` | Embedded pattern-match modifier. MODIFIER can be one or more of i, m, s, or x.
Quantified subpatterns match as many times as possible. When followed with a `?` they match the minimum number of times. These are the quantifiers:
`+` | matches the preceding pattern element one or more times.
`?` | matches zero or one times.
`*` | matches zero or more times.
`{`N`,`M`}` | denotes the minimum N and maximum M match count. `{`N`}` means exactly N times; `{`N`,``}` means at least N times.
A `\` escapes any special meaning of the following character if non-alphanumeric, but it turns most alphanumeric characters into something special:
`\w` | matches alphanumeric, including `_`, `\W` matches non-alphanumeric.
`\s` | matches whitespace, `\S` matches non-whitespace.
`\d` | matches numeric, `\D` matches non-numeric.
`\A` | matches the beginning of the string, `\Z` matches the end.
`\b` | matches word boundaries, `\B` matches non-boundaries.
`\G` | matches where the previous m//g search left off.
`\n`, `\r`, `\f`, `\t` | etc. have their usual meaning.
`\w`, `\s` and `\d` | may be used within character classes, `\b` denotes backspace in this context.
Back-references:
`\1` ... `\9` | refer to matched subexpressions, grouped with `()`, inside the match.
`\10` | and up can also be used if the pattern matches that many subexpressions.

See also `$1` ... `$9`,`$+`,`$&`,`$``, and`$'` in section Special Variables.

With modifier x, whitespace can be used in the patterns for readability purposes.

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## Search and Replace Functions

[ EXPR `=~` ] [ m ] `/`PATTERN`/` [ g ] [ i ] [ m ] [ o ] [ s ] [ x ]
  Searches EXPR (default: `$_`) for a pattern. If you prepend an m you can use almost any pair of delimiters instead of the slashes. If used in array context, an array is returned consisting of the subexpressions matched by the parentheses in the pattern, i.e., `($1,$2,$3,`...`)`.
  Optional modifiers: g matches as many times as possible; i searches in a case-insensitive manner; o interpolates variables only once. m treats the string as multiple lines; s treats the string as a single line; x allows for regular expression extensions.
  If PATTERN is empty, the most recent pattern from a previous match or replacement is used.
  With g the match can be used as an iterator in scalar context.
`?`PATTERN`?`
  This is just like the `/`PATTERN`/` search, except that it matches only once between calls to the reset operator.
[ `$`VAR `=~` ] s`/`PATTERN`/`REPLACEMENT`/` [ e ] [ g ] [ i ] [ m ] [ o ] [ s ] [ x ]
  Searches a string for a pattern, and if found, replaces that pattern with the replacement text. It returns the number of substitutions made, if any; if no substitutions are made, it returns false.
  Optional modifiers: g replaces all occurrences of the pattern; e evaluates the replacement string as a Perl expression; for any other modifiers, see `/`PATTERN`/` matching. Almost any delimiter may replace the slashes; if single quotes are used, no interpretation is done on the strings between the delimiters, otherwise the strings are interpolated as if inside double quotes.
  If bracketing delimiters are used, PATTERN and REPLACEMENT may have their own delimiters, e.g., `s(foo)[bar]`. If PATTERN is empty, the most recent pattern from a previous match or replacement is used.
[ `$`VAR `=~` ] tr`/`SEARCHLIST`/`REPLACEMENTLIST`/` [ c ] [ d ] [ s ]
  Translates all occurrences of the characters found in the search list with the corresponding character in the replacement list. It returns the number of characters replaced. y may be used instead of tr.
  Optional modifiers: c complements the SEARCHLIST; d deletes all characters found in SEARCHLIST that do not have a corresponding character in REPLACEMENTLIST; s squeezes all sequences of characters that are translated into the same target character into one occurrence of this character.
pos SCALAR
  Returns the position where the last m//g search left off for SCALAR. May be assigned to.
study [ `$`VAR† ]
  Study the scalar variable `$`VAR in anticipation of performing many pattern matches on its contents before the variable is next modified.

#### Back to Contents or Index

## File Test Operators

These unary operators takes one argument, either a filename or a filehandle, and test the associated file to see if something is true about it. If the argument is omitted, they test `$_` (except for `-t`, which tests `STDIN`). If the special argument `_` (underscore) is passed, they use the information from the preceding test or stat call.

`-r -w -x` | File is readable/writable/executable by effective uid/gid.
`-R -W -X` | File is readable/writable/executable by real uid/gid.
`-o -O` | File is owned by effective/real uid.
`-e -z` | File exists/has zero size.
`-s` | File exists and has non-zero size. Returns the size.
`-f -d` | File is a plain file/a directory.
`-l -S -p` | File is a symbolic link/a socket/a named pipe (FIFO).
`-b -c` | File is a block/character special file.
`-u -g -k` | File has setuid/setgid/sticky bit set.
`-t` | Tests if filehandle (`STDIN` by default) is opened to a tty.
`-T -B` | File is a text/non-text (binary) file. `-T` and `-B` return true on a null file, or a file at EOF when testing a filehandle.
`-M -A -C` | File modification / access / inode-change time. Measured in days. Value returned reflects the file age at the time the script started. See also `$^T` in the section Special Variables.

#### Back to Contents or Index

## File Operations

Functions operating on a list of files return the number of files successfully operated upon.

chmod LIST
  Changes the permissions of a list of files. The first element of the list must be the numerical mode.
chown LIST
  Changes the owner and group of a list of files. The first two elements of the list must be the numerical uid and gid.
truncate FILE`,` SIZE
  Truncates FILE to SIZE. FILE may be a filename or a filehandle.
link OLDFILE`,` NEWFILE
  Creates a new filename linked to the old filename.
lstat FILE
  Like stat, but does not traverse a final symbolic link.
mkdir DIR`,` MODE
  Creates a directory with given permissions. Sets `$!` on failure.
readlink EXPR†
  Returns the value of a symbolic link.
rename OLDNAME`,` NEWNAME
  Changes the name of a file.
rmdir FILENAME†
  Deletes the directory if it is empty. Sets `$!` on failure.
stat FILE
  Returns a 13-element array (0: `$`dev, 1: `$`ino, 2: `$`mode, 3: `$`nlink, 4: `$`uid, 5: `$`gid, 6: `$`rdev, 7: `$`size, 8: `$`atime, 9: `$`mtime, 10: `$`ctime, 11: `$`blksize, 12: `$`blocks). FILE can be a filehandle, an expression evaluating to a filename, or `_` to refer to the last file test operation or stat call. Returns a null list if the stat fails.
symlink OLDFILE, NEWFILE
  Creates a new filename symbolically linked to the old filename.
unlink LIST
  Deletes a list of files.
utime LIST
  Changes the access and modification times. The first two elements of the list must be the numerical access and modification times.

#### Back to Contents or Index

## Input / Output

In input/output operations, FILEHANDLE may be a filehandle as opened by the open operator, a predefined filehandle (e.g., `STDOUT`) or a scalar variable that evaluates to the name of a filehandle to be used.

`<`FILEHANDLE`>`
  In scalar context, reads a single line from the file opened on FILEHANDLE. In array context, reads the whole file.
`<` `>`
  Reads from the input stream formed by the files specified in `@ARGV`, or standard input if no arguments were supplied.
binmode FILEHANDLE
  Arranges for the file opened on FILEHANDLE to be read or written in binary mode as opposed to text mode (null operation on UNIX).
close FILEHANDLE
  Closes the file or pipe associated with the filehandle.
dbmclose `%`HASH
  Deprecated, use untie instead.
dbmopen `%`HASH`,` DBMNAME`,` MODE
  Deprecated, use tie instead.
eof FILEHANDLE
  Returns true if the next read will return end of file, or if the file is not open.
eof
  Returns the EOF status for the last file read.
eof`()`
  Indicates EOF on the pseudo file formed of the files listed on the command line.
fcntl FILEHANDLE`,` FUNCTION`,` `$`VAR
  Implements the fcntl(2) function. This function has non-standard return values.
fileno FILEHANDLE
  Returns the file descriptor for a given (open) file.
flock FILEHANDLE`,` OPERATION
  Calls flock(2) on the file. OPERATION formed by adding 1 (shared), 2 (exclusive), 4 (non-blocking), or 8 (unlock).
getc [ FILEHANDLE ]
  Yields the next character from the file, or an empty string on end of file. If FILEHANDLE is omitted, reads from `STDIN`.
ioctl FILEHANDLE`,` FUNCTION`,` `$`VAR
  Performs ioctl(2) on the file. This function has non-standard return values.
open FILEHANDLE [ `,` FILENAME ]
  Opens a file and associates it with FILEHANDLE. If FILENAME is omitted, the scalar variable of the same name as the FILEHANDLE must contain the filename.
  The following filename conventions apply when opening a file.

  `"`FILE`"` | open FILE for input. Also `"<`FILE`"`.
  `">`FILE`"` | open FILE for output, creating it if necessary.
  `">>`FILE`"` | open FILE in append mode.
  `"+<`FILE`"` | open FILE with read/write access (file must exist).
  `"+>`FILE`"` | open FILE with read/write access (file truncated).
  `"|`CMD`"` | opens a pipe to command CMD; forks if CMD is `-`.
  `"`CMD`|"` | opens a pipe from command CMD; forks if CMD is `-`.

  FILE may be `&`FILEHND in which case the new filehandle is connected to the (previously opened) filehandle FILEHND. If it is `&=`N, FILE will be connected to the given file descriptor. open returns undef upon failure, true otherwise.
pipe READHANDLE`,` WRITEHANDLE``
  Returns a pair of connected pipes.
print [ FILEHANDLE ] [ LIST† ]
  Equivalent to print FILEHANDLE sprintf LIST.
printf[`(`[FILEHANDLE] LIST†`)`]
  Equivalent to print FILEHANDLE sprintf`(`LIST`)`.
read FILEHANDLE`,` `$`VAR`,` LENGTH [ `,` OFFSET ]
  Reads LENGTH binary bytes from the file into the variable at OFFSET. Returns number of bytes actually read.
seek FILEHANDLE`,` POSITION`,` WHENCE
  Arbitarily positions the file. Returns true if successful.
select [ FILEHANDLE ]
  Returns the currently selected filehandle. Sets the current default filehandle for output operations if FILEHANDLE is supplied.
select RBITS`,` WBITS`,` NBITS`,` TIMEOUT
  Performs a select(2) system call with the same parameters.
sprintf FORMAT`,` LIST
  Returns a string formatted by (almost all of) the usual printf(3) conventions.
sysread FILEHANDLE`,` `$`VAR`,` LENGTH [ `,` OFFSET ]
  Reads LENGTH bytes into `$`VAR at OFFSET.
syswrite FILEHANDLE`,` SCALAR`,` LENGTH [ `,` OFFSET ]
  Writes LENGTH bytes from SCALAR at OFFSET.
tell [ FILEHANDLE ]
  Returns the current file position for the file. If FILENAME is omitted, assumes the file last read.
write [ FILEHANDLE ]
  Writes a formatted record to the specified file, using the format associated with that file.

#### Back to Contents or Index

## Formats

formline PICTURE`,` LIST
  Formats LIST according to PICTURE and accumulates the result into `$^A`.
write [ FILEHANDLE ]
  Writes a formatted record to the specified file, using the format associated with that file.

Formats are defined as follows:

format [NAME] `=`
FORMLIST
`.`

FORMLIST pictures the lines, and contains the arguments which will give values to the fields in the lines. NAME defaults to `STDOUT` if omitted.

Picture fields are:

`@<<<`... | left adjusted field, repeat the `<` to denote the desired width
`@>>>`... | right adjusted field
`@|||`... | centered field
`@#.##`... | numeric format with implied decimal point
`@*` | a multi-line field

Use `^` instead of `@` for multiline block filling.
Use `~` at the beginning of a line to suppress unwanted empty lines.
Use `~~` at the beginning of a line to have this format line repeated until all fields are exhausted.
Use `$-` to zero to force a page break on the next write.
See also `$^`, `$~`, `$^A`, `$^F`, `$-` and `$=` in section Special Variables.

#### Back to Contents or Index

## Directory Reading Routines

closedir DIRHANDLE
  Closes a directory opened by opendir.
opendir DIRHANDLE`,` DIRNAME
  Opens a directory on the handle specified.
readdir DIRHANDLE
  Returns the next entry (or an array of entries) from the directory.
rewinddir DIRHANDLE
  Positions the directory to the beginning.
seekdir DIRHANDLE`,` POS
  Sets position for readdir on the directory.
telldir DIRHANDLE
  Returns the position in the directory.

#### Back to Contents or Index

## System Interaction

alarm EXPR
  Schedules a `SIGALRM` to be delivered after EXPR seconds.
chdir [ EXPR ]
  Changes the working directory. Uses `$ENV{"HOME"}` or `$ENV{"LOGNAME"}` if EXPR is omitted.
chroot FILENAME†
  Changes the root directory for the process and its children.
die [ LIST ]
  Prints the value of LIST to `STDERR` and exits with the current value of `$!` (errno). If `$!` is 0, exits with the value of `($? >> 8)`. If `($? >> 8)` is 0, exits with 255. LIST defaults to "`Died`".
exec LIST
  Executes the system command in LIST; does not return.
exit [ EXPR ]
  Exits immediately with the value of EXPR, which defaults to `0` (zero). Calls `END` routines and object destructors before exiting.
fork
  Does a fork(2) system call. Returns the process ID of the child to the parent process and zero to the child process.
getlogin
  Returns the current login name as known by the system.
getpgrp [ PID ]
  Returns the process group for process PID (0, or omitted, means the current process).
getppid
  Returns the process ID of the parent process.
getpriority WHICH`,` WHO
  Returns the current priority for a process, process group, or user.
glob PAT
  Returns a list of filenames that match the shell pattern PAT.
kill LIST
  Sends a signal to a list of processes. The first element of the list must be the signal to send (either numeric, or its name as a string).
setpgrp PID`,` PGRP
  Sets the process group for the PID (0 means the current process).
setpriority WHICH`,` WHO`,` PRIORITY
  Sets the current priority for a process, process group, or a user.
sleep [ EXPR ]
  Causes the program to sleep for EXPR seconds, or forever if no EXPR. Returns the number of seconds actually slept.
syscall LIST
  Calls the system call specified in the first element of the list, passing the rest of the list as arguments to the call.
system LIST
  Does exactly the same thing as exec LIST except that a fork is performed first, and the parent process waits for the child process to complete.
times
  Returns a 4-element array (0: `$`user, 1: `$`system, 2: `$`cuser, 3: `$`csystem) giving the user and system times, in seconds, for this process and the children of this process.
umask [ EXPR ]
  Sets the umask for the process and returns the old one. If EXPR is omitted, returns current umask value.
wait
  Waits for a child process to terminate and returns the process ID of the deceased process (-1 if none). The status is returned in `$?`.
waitpid PID`,` FLAGS
  Performs the same function as the corresponding system call.
warn [ LIST ]
  Prints the message on `STDERR` like die, but doesn't exit. LIST defaults to "`Warning: something's wrong`".

#### Back to Contents or Index

## Networking

accept NEWSOCKET`,` GENERICSOCKET
  Accepts a new socket.
bind SOCKET`,` NAME
  Binds the NAME to the SOCKET.
connect SOCKET`,` NAME
  Connects the NAME to the SOCKET.
getpeername SOCKET
  Returns the socket address of the other end of the SOCKET.
getsockname SOCKET
  Returns the name of the SOCKET.
getsockopt SOCKET`,` LEVEL`,` OPTNAME
  Returns the socket options.
listen SOCKET`,` QUEUESIZE
  Starts listening on the specified SOCKET.
recv SOCKET`,` SCALAR`,` LENGTH`,` FLAGS
  Receives a message on SOCKET.
send SOCKET`,` MSG`,` FLAGS [ `,` TO ]
  Sends a message on the SOCKET.
setsockopt SOCKET`,` LEVEL`,` OPTNAME`,` OPTVAL
  Sets the requested socket option.
shutdown SOCKET`,` HOW
  Shuts down a SOCKET.
socket SOCKET`,` DOMAIN`,` TYPE`,` PROTOCOL
  Creates a SOCKET in DOMAIN with TYPE and PROTOCOL.
socketpair SOCKET1`,` SOCKET2`,` DOMAIN`,` TYPE`,` PROTOCOL
  Works the same as socket, but creates a pair of bidirectional sockets.

#### Back to Contents or Index

## System V IPC

You need to`require "sys/ipc.ph"` before you can use the symbolic names of the operations.

msgctl ID`,` CMD`,` ARGS
  Calls msgctl(2). If CMD is `&IPC_STAT` then ARGS must be a variable.
msgget KEY`,` FLAGS
  Creates a message queue for KEY. Returns the message queue identifier.
msgsnd ID`,` MSG`,` FLAGS
  Sends MSG to queue ID.
msgrcv ID`,` `$`VAR`,` SIZE`,` TYPE`,` FLAGS
  Receives a message from queue ID into VAR.
semctl ID`,` SEMNUM`,` CMD`,` ARG
  Calls semctl(2). If CMD is `&IPC_STAT` of `&GETALL` then ARG must be a variable.
semget KEY`,` NSEMS`,` SIZE`,` FLAGS
  Creates a set of semaphores for KEY. Returns the message semaphore identifier.
semop KEY`,` ...
  Performs semaphore operations.
shmctl ID`,` CMD`,` ARG
  Calls shmctl(2). If CMD is `&IPC_STAT` then ARG must be a variable.
shmget KEY`,` SIZE`,` FLAGS
  Creates shared memory. Returns the shared memory segment identifier.
shmread ID`,` `$`VAR`,` POS`,` SIZE
  Reads at most SIZE bytes of the contents of shared memory segment ID starting at offset POS into VAR.
shmwrite ID`,` STRING`,` POS`,` SIZE
  Writes at most SIZE bytes of STRING into the contents of shared memory segment ID at offset POS.

#### Back to Contents or Index

## Miscellaneous

defined EXPR
  Tests whether the lvalue EXPR has an actual value.
do FILENAME
  Executes FILENAME as a Perl script. See also require in the section Subroutines, Packages and Modules.
dump [ LABEL ]
  Immediate core dump. When reincarnated, starts at LABEL.
eval `{` EXPR `;` ... `}`
  Executes the code between `{` and `}`. Traps runtime errors as described with eval`(`EXPR`)`, in the section String Functions.
local VARIABLE
local `(` LIST `)`
  Creates a scope for the listed variables local to the enclosing block, subroutine or eval.
my VARIABLE
my `(` LIST `)`
  Creates a scope for the listed variables lexically local to the enclosing block, subroutine or eval.
ref EXPR†
  Returns a true value if EXPR is a reference. Returns the package name if EXPR has been blessed into a package.
reset [ EXPR ]
  Resets `??` searches so that they work again. EXPR is a list of single letters. All variables and arrays beginning with one of those letters are reset to their pristine state. Only affects the current package.
scalar EXPR
  Forces evaluation of EXPR in scalar context.
undef [ LVALUE ]
  Undefines the LVALUE. Always returns the undefined value.
wantarray
  Returns true if the current context expects an array value.

#### Back to Contents or Index

## Information from System Files

• passwd
Returns `($`name, `$`passwd, `$`uid, `$`gid, `$`quota, `$`comment, `$`gcos, `$`dir, `$`shell`)`.
endpwent | Ends lookup processing.
getpwent | Gets next user information.
getpwnam NAME | Gets information by name.
getpwuid UID | Gets information by user ID.
setpwent | Resets lookup processing.
• group
Returns `($`name, `$`passwd, `$`gid, `$`members`)`.
endgrent | Ends lookup processing.
getgrgid GID | Gets information by group ID.
getgrnam NAME | Gets information by name.
getgrent | Gets next information.
setgrent | Resets lookup processing.
• hosts
Returns `($`name, `$`aliases, `$`addrtype, `$`length, `@`addrs`)`.
endhostent | Ends lookup processing.
gethostbyaddr ADDR`,` ADDRTYPE | Gets information by IP address.
gethostbyname NAME | Gets information by hostname.
gethostent | Gets next host information.
sethostent STAYOPEN | Resets lookup processing.
• networks
Returns `($`name, `$`aliases, `$`addrtype, `$`net`)`.
endnetent | Ends lookup processing.
getnetbyaddr ADDR`,` TYPE | Gets information by address and type.
getnetbyname NAME | Gets information by network name.
getnetent | Gets next network information.
setnetent STAYOPEN | Resets lookup processing.
• services
Returns `($`name, `$`aliases, `$`port, `$`proto`)`.
endservent | Ends lookup processing.
getservbyname NAME`,` PROTO | Gets information by service name.
getservbyport PORT`,` PROTO | Gets information by service port.
getservent | Gets next service information.
setservent STAYOPEN | Resets lookup processing.
• protocols
Returns `($`name, `$`aliases, `$`proto`)`.
endprotoent | Ends lookup processing.
getprotobyname NAME | Gets information by protocol name.
getprotobynumber NUMBER | Gets information by protocol number.
getprotoent | Gets next protocol information.
setprotoent STAYOPEN | Resets lookup processing.

#### Back to Contents or Index

## Special Variables

The following variables are global and should be localized in subroutines:
`$_` | The default input and pattern-searching space.
`$.` | The current input line number of the last filehandle that was read.
`$/` | The input record separator, newline by default. May be multicharacter.
`$,` | The output field separator for the print operator.
`$"` | The separator that joins elements of arrays interpolated in strings.
`$\` | The output record separator for the print operator.
`$#` | The output format for printed numbers. Deprecated.
`$*` | Set to 1 to do multiline matching within strings. Deprecated, see the m and s modifiers in section Search and Replace Functions.
`$?` | The status returned by the last ```...``` command, pipe close or system operator.
`$]` | The perl version number, e.g., `5.001`.
`$[` | The index of the first element in an array, and of the first character in a substring. Default is 0. Deprecated.
`$;` | The subscript separator for multidimensional array emulation. Default is "`\034`".
`$!` | If used in a numeric context, yields the current value of errno. If used in a string context, yields the corresponding error string.
`$@` | The Perl error message from the last eval or do EXPR command.
`$:` | The set of characters after which a string may be broken to fill continuation fields (starting with `^`) in a format.
`$0` | The name of the file containing the Perl script being executed. May be assigned to.
`$$` | The process ID of the currently executing Perl program. Altered (in the child process) by fork.
`$<` | The real user ID of this process.
`$>` | The effective user ID of this process.
`$(` | The real group ID of this process.
`$)` | The effective group ID of this process.
`$^A` | The accumulator for formline and write operations.
`$^D` | The debug flags as passed to perl using `-D`.
`$^F` | The highest system file descriptor, ordinarily 2.
`$^I` | In-place edit extension as passed to Perl using `-i`.
`$^L` | Formfeed character used in formats.
`$^P` | Internal debugging flag.
`$^T` | The time (as delivered by time) when the program started. This value is used by the file test operators `-M`, `-A` and `-C`.
`$^W` | The value of the `-w` option as passed to Perl.
`$^X` | The name by which the currently executing program was invoked.
The following variables are context dependent and need not be localized:
`$%` | The current page number of the currently selected output channel.
`$=` | The page length of the current output channel. Default is 60 lines.
`$-` | The number of lines remaining on the page.
`$~` | The name of the current report format.
`$^` | The name of the current top-of-page format.
`$|` | If set to nonzero, forces a flush after every write or print on the currently selected output channel. Default is 0.
`$ARGV` | The name of the current file when reading from `<>`.
The following variables are always local to the current block:
`$&` | The string matched by the last successful pattern match.
`$`` | The string preceding what was matched by the last successful match.
`$'` | The string following what was matched by the last successful match.
`$+` | The last bracket matched by the last search pattern.
`$1`...`$9`... | Contain the subpatterns from the corresponding sets of parentheses in the last pattern successfully matched. `$10`... and up are only available if the match contained that many subpatterns.

#### Back to Contents or Index

## Special Arrays

`@ARGV` | Contains the command-line arguments for the script (not including the command name).
`@EXPORT` | Names the methods a package exports by default.
`@EXPORT_OK` | Names the methods a package can export upon explicit request.
`@INC` | Contains the list of places to look for Perl scripts to be evaluated by the do FILENAME and require commands.
`@ISA` | List of base classes of a package.
`@_` | Parameter array for subroutines. Also used by split if not in array context.
`%ENV` | Contains the current environment.
`%INC` | List of files that have been included with require or do.
`%OVERLOAD` | Can be used to overload operators in a package.
`%SIG` | Used to set signal handlers for various signals.

#### Back to Contents or Index

## Environment Variables

Perl uses the following environment variables.

`HOME` | Used if chdir has no argument.
`LOGDIR` | Used if chdir has no argument and `HOME` is not set.
`PATH` | Used in executing subprocesses, and in finding the Perl script if `-S` is used.
`PERL5LIB` | A colon-separated list of directories to look in for Perl library files before looking in the standard library and the current directory.
`PERL5DB` | The command to get the debugger code. Defaults to `BEGIN { require 'perl5db.pl' }`.
`PERLLIB` | Used instead of `PERL5LIB` if the latter is not defined.

#### Back to Contents or Index

## The Perl Debugger

The Perl symbolic debugger is invoked with `perl -d`.

`h` | Prints out a help message.
`T` | Prints a stack trace.
`s` | Single steps.
`n` | Single steps around subroutine call.
RETURN key | Repeats last `s` or `n`.
`r` | Returns from the current subroutine.
`c` [ LINE ] | Continues (until LINE, or another breakpoint, or exit).
`p` EXPR | Prints EXPR.
`l` [ RANGE ] | Lists a range of lines. RANGE may be a number, start-end, start+amount, or a subroutine name. If RANGE is omitted, lists next window.
`w` | Lists window around current line.
`-` | Lists previous window.
`f` FILE | Switches to FILE and starts listing it.
`l` SUB | Lists the named subroutine.
`S` | List the names of all subroutines.
`/`PATTERN`/` | Searches forward for PATTERN.
`?`PATTERN`?` | Searches backward for PATTERN.
`b` [ LINE [ CONDITION ] ] | Sets breakpoint at LINE; default is the current line.
`b` SUB [ CONDITION ] | Sets breakpoint at the subroutine.
`d` [ LINE ] | Deletes breakpoint at the given line.
`D` | Deletes all breakpoints.
`L` | Lists lines that have breakpoints or actions.
`a` LINE COMMAND | Sets an action for line.
`A` | Deletes all line actions.
`<` COMMAND | Sets an action to be executed before every debugger prompt.
`>` COMMAND | Sets an action to be executed before every `s`, `c` or `n` command.
`V` [ PACKAGE [ VARS ] ] | Lists all variables in a package. Default package is `main`.
`X` [ VARS ] | Like `V`, but assumes current package.
`!` [ [`-`]NUMBER ] | Re-executes a command. Default is the previous command.
`H` [ -NUMBER ] | Displays the last `-`NUMBER commands of more than one letter.
`t` | Toggles trace mode.
`=` [ ALIAS VALUE ] | Sets alias, or lists current aliases.
`q` | Quits. You may also use your EOF key character.
COMMAND | Executes COMMAND as a Perl statement.

#### Back to Contents or Index

### Other Summaries and Demos

- See my home page for other summaries and demos: APL, REXX, XEDIT, KEDIT, Perl, HTML, RGB Colors, HTTP Cookies, Email Forms, CGI Environment Variables, Server Side Includes, etc...

Sorry, but I do not have time to provide free answers to questions about Perl.
(I'm busy trying to make a living!) So please don't e-mail your questions to me.

Text copyright © 1996 Johan Vromans
HTML copyright © 1996-2003 Rex Swain
Email rex@rexswain.com, Web http://www.rexswain.com
Reports of errors or omissions appreciated