Perl reference - Revision history

Woozle: Reverted edits by MMason73 (talk) to last revision by Woozle

2011-10-01T17:58:37Z

Reverted edits by MMason73 (talk) to last revision by Woozle

MMason73: None

2011-09-26T15:13:38Z

None

Woozle: /* Escape Sequences */ example of \cn

2006-04-07T23:04:33Z

Escape Sequences: example of \cn

← Older revision		Revision as of 23:04, 7 April 2006
Line 7:		Line 7:
	\| '''\b''' \|\| backspace (ctrl-H, 008 decimal)		\| '''\b''' \|\| backspace (ctrl-H, 008 decimal)
	\|-		\|-
	\| '''\c'''''n'' \|\| ctrl-''n''		\| '''\c'''<u>n</u> \|\| ctrl-<u>n</u> (e.g. \cj = CTRL-J, i.e. Line Feed)
	\|-		\|-
	\| '''\e''' \|\| ESC (027 decimal, 033 octal)		\| '''\e''' \|\| ESC (027 decimal, 033 octal)
Line 41:		Line 41:
	\| '''\x'''''nn'' \|\| prints the ASCII character numbered ''nn'' in hexadecimal		\| '''\x'''''nn'' \|\| prints the ASCII character numbered ''nn'' in hexadecimal
	\|}		\|}

	==Operators==		==Operators==
	===Arithmetic===		===Arithmetic===

Woozle: /* Special Variables */ found a bunch more in Barkakati

2006-04-07T11:37:50Z

Special Variables: found a bunch more in Barkakati

← Older revision		Revision as of 11:37, 7 April 2006
Line 128:		Line 128:
	\|-		\|-
	\| '''%ENV''' \|\| hash of all environment variables (see http://vbz.net/cgi-bin/env for a sample listing)		\| '''%ENV''' \|\| hash of all environment variables (see http://vbz.net/cgi-bin/env for a sample listing)
			\|-
			\| '''$0''' \|\| name of Perl program file (the outermost one; may or may not include path, depending on system (in Linux, it does not))
			\|-
			\| '''$^A''' \|\| current value of the accumulator used by the [[write (Perl)\|write]]() function
			\|-
			\| '''$^D''' \|\| current value of Perl's debugging flags
			\|-
			\| '''$^F''' \|\| maximum system file descriptor (typically 2) ''not sure what this means''
			\|-
			\| '''$^L''' \|\| what characters are printed to accomplish a [[form feed]]
			\|-
			\| '''$^T''' \|\| time at which the script began running, in seconds since 00:00:00 GMT January 1, 1970
			\|-
			\| '''$^W''' \|\| is true if warnings have been turned on (by running Perl with the -w command option)
			\|-
			\| '''$^X''' \|\| [[filespec]] of the Perl interpreter
	\|-		\|-
	\| '''$_''' \|\| The default input and pattern-searching space; default argument for many functions.		\| '''$_''' \|\| The default input and pattern-searching space; default argument for many functions.
Line 133:		Line 149:
	\| '''@_''' \|\| list of arguments passed to subroutine (usually in parentheses)		\| '''@_''' \|\| list of arguments passed to subroutine (usually in parentheses)
	\|-		\|-
	\| '''$0''' \|\| ~~name~~ of ~~Perl program file~~ (the ~~outermost one; may or may not include path, depending on system~~ (in Linux~~, it does not)~~)		\| '''$)''' \|\| effective group ID of the current process (UNIX/Linux)
			\|-
			\| '''$(''' \|\| real group ID of the current process (UNIX/Linux)
	\|-		\|-
	\| '''$]''' \|\| version number of the Perl interpreter		\| '''$]''' \|\| version number of the Perl interpreter
Line 139:		Line 157:
	\| '''$[''' \|\| The index of the first element in an array, and of the first character in a substring.		\| '''$[''' \|\| The index of the first element in an array, and of the first character in a substring.
	\|-		\|-
	\| '''$<''' \|\| username of user running the Perl script (may not be very useful for CGI because Apache always executes as the same user)		\| '''$<''' \|\| <s>username of user running the Perl script</s> real user ID of the current process (UNIX/Linux) (may not be very useful for CGI because Apache always executes as the same user)
	\|-		\|-
	\| '''$^X''' \|\| ~~[[filespec]]~~ of the ~~Perl interpreter~~		\| '''$>''' \|\| effective user ID of the current process (UNIX/Linux)
	\|-		\|-
	\| '''$/''' \|\| string to be used as input record separator; default = newline		\| '''$/''' \|\| string to be used as input record separator; default = newline
	\|-		\|-
	\| '''$\''' \|\| string to be used as output record separator in [[print (Perl ~~function~~)\|print]]		\| '''$\''' \|\| string to be used as output record separator in [[print (Perl)\|print]]()
	\|-		\|-
	\| ''';''' \|\| The subscript separator for multi-dimensional array emulation.		\| '''$:''' \|\| "soft-hyphen" characters, i.e. the set of characters after which a line may be broken to fill continuation fields (starting with ^) in a format. Default is space, newline, hyphen.
			\|-
			\| '''$;''' \|\| The subscript separator for multi-dimensional array emulation.
	\|-		\|-
	\| '''$.''' \|\| The current input line number (or record number) of the last filehandle that was read.		\| '''$.''' \|\| The current input line number (or record number) of the last filehandle that was read.
	\|-		\|-
	\| '''$,''' \|\| separator for printing arrays		\| '''$,''' \|\| output field separator for [[print (Perl)\|print]]() function, i.e. the separator for printing arrays
	\|-		\|-
	\| '''$"''' \|\| This is similar to "$," except that it applies to array values interpolated into a double-quoted string (or similar interpreted string)		\| '''$"''' \|\| This is similar to "'''$,'''" except that it applies to array values interpolated into a double-quoted string (or similar interpreted string)
	\|-		\|-
	\| '''$#''' \|\| The output format for numbers display via [[print (Perl ~~function~~)\|print]]		\| '''$#''' \|\| The output format for numbers display via [[print (Perl)\|print]]()
	\|-		\|-
	\| '''$$''' \|\| The process number of the Perl running this script		\| '''$$''' \|\| The process number of the Perl running this script
	\|-		\|-
	\| '''$?''' \|\| The status returned by the last pipe close, backtick(``) command or system operator.		\| '''$?''' \|\| The status returned by the last child process, i.e. pipe close, backtick(``) command or system operator.
	\|-		\|-
	\| '''$!''' \|\| If used in a numeric context, yields the current value of errno, with all the usual caveats. (This means that you shouldn't depend on the value of $! to be anything in particular unless you've gotten a specific error return indicating a system error.) If used in a string context, yields the corresponding sysem error string.		\| '''$!''' \|\| If used in a numeric context, yields the current value of errno, with all the usual caveats. (This means that you shouldn't depend on the value of $! to be anything in particular unless you've gotten a specific error return indicating a system error.) If used in a string context, yields the corresponding sysem error string.
Line 182:		Line 202:
	\| '''$-''' \|\| Number of lines remaining on the page		\| '''$-''' \|\| Number of lines remaining on the page
	\|-		\|-
	\| '''$~''' \|\| Name of the current report format		\| '''$~''' \|\| Name of the current report format (default is the filenandle's name)
	\|-		\|-
	\| '''$^''' \|\| Name of the current top-of-page format		\| '''$^''' \|\| Name of the current top-of-page format (default is the filehandle's name plus "_TOP")
	\|-		\|-
	\| colspan=2 \|		\| colspan=2 \|
Line 199:		Line 219:
	\|-		\|-
	\| '''$+''' \|\| The last bracket matched by the last search pattern. This is useful if you don't know which of a set of alternative patterns matched.		\| '''$+''' \|\| The last bracket matched by the last search pattern. This is useful if you don't know which of a set of alternative patterns matched.
			\|-
			\| '''$*''' \|\| When set to 1, string searching is done for multiple lines within the string (i.e. if the string contains newline characters); otherwise, presumably the search stops at the first newline.
	\|-		\|-
	\|		\|
	\|}		\|}
	Portions of this were shamelessly copied from [http://www.kichwa.com/quik_ref/spec_variables.html here], at least until more information can be found.		Portions of this were shamelessly copied from [http://www.kichwa.com/quik_ref/spec_variables.html here], at least until more information can be found. Other portions were copied from ''Discover Perl 5'' by Naba Barkakati, ISBN 0-7645-3076-3

Woozle: /* Pattern Matching (regex) */ three of these introduce significant overhead

2006-03-29T21:56:14Z

Pattern Matching (regex): three of these introduce significant overhead

← Older revision		Revision as of 21:56, 29 March 2006
Line 192:		Line 192:
	\| '''$<u>n</u>''' \|\| in the replacement section, indicate that the <u>n</u><sup>th</sup> matched section in parentheses should be used here (first matched parentheses becomes $1, second becomes $2, etc., up through $9)		\| '''$<u>n</u>''' \|\| in the replacement section, indicate that the <u>n</u><sup>th</sup> matched section in parentheses should be used here (first matched parentheses becomes $1, second becomes $2, etc., up through $9)
	\|-		\|-
	\| '''$&''' \|\| Contains the string matched by the last pattern match		\| '''$&''' \|\| Contains the string matched by the last pattern match. ''Introduces CPU/memory overhead for all regex operations in the script; avoid.''
	\|-		\|-
	\| '''$`''' \|\| The string preceding whatever was matched by the last pattern match, not counting patterns matched in nested blocks that have been exited already.		\| '''$`''' \|\| The string preceding whatever was matched by the last pattern match, not counting patterns matched in nested blocks that have been exited already. ''Introduces CPU/memory overhead for all regex operations in the script; avoid.''
	\|-		\|-
	\| '''$'''' \|\| The string following whatever was matched by the last pattern match, not counting patterns matched in nested blockes that have been exited already.		\| '''$'''' \|\| The string following whatever was matched by the last pattern match, not counting patterns matched in nested blockes that have been exited already. ''Introduces CPU/memory overhead for all regex operations in the script; avoid.''
	\|-		\|-
	\| '''$+''' \|\| The last bracket matched by the last search pattern. This is useful if you don't know which of a set of alternative patterns matched.		\| '''$+''' \|\| The last bracket matched by the last search pattern. This is useful if you don't know which of a set of alternative patterns matched.

Woozle: /* File Test Operators */ regular operators

2006-03-26T02:17:26Z

File Test Operators: regular operators

@@ Line 40: / Line 40: @@
 |-
 | '''\x'''''nn'' || prints the ASCII character numbered ''nn'' in hexadecimal
 |}
 ==File Test Operators==
@@ Line 76: / Line 121: @@
 | '''-A''' || Number of days since file was last accessed
 |}
 ==Special Variables==
 {|

Woozle: /* Special Variables */ minor formatting fix

2006-03-25T23:01:57Z

Special Variables: minor formatting fix

← Older revision		Revision as of 23:01, 25 March 2006
Line 118:		Line 118:
	\|-		\|-
	\| '''$@''' \|\| The Perl syntax error or routine error message from the last eval, do-FILE, or require command. If set, either the compilation failed, or the die function was executed within the code of the eval.		\| '''$@''' \|\| The Perl syntax error or routine error message from the last eval, do-FILE, or require command. If set, either the compilation failed, or the die function was executed within the code of the eval.
			\|-
	\| colspan=2 \|		\| colspan=2 \|
	===Output Flags===		===Output Flags===

Woozle: /* Special Variables */ and hopefully that's all

2006-03-13T00:44:39Z

Special Variables: and hopefully that's all

@@ Line 83: / Line 83: @@
 | '''%ENV''' || hash of all environment variables (see http://vbz.net/cgi-bin/env for a sample listing)
 |-
-| '''$_''' || default argument for many functions
+| '''$_''' || The default input and pattern-searching space; default argument for many functions.
 |-
 | '''@_''' || list of arguments passed to subroutine (usually in parentheses)
 |-
-| '''$0''' || name of Perl program file (the outermost one, and just the name without any path)
+| '''$0''' || name of Perl program file (the outermost one; may or may not include path, depending on system (in Linux, it does not))
 |-
 | '''$]''' || version number of the Perl interpreter
 |-
 | '''$<''' || username of user running the Perl script (may not be very useful for CGI because Apache always executes as the same user)
@@ Line 95: / Line 97: @@
 | '''$^X''' || [[filespec]] of the Perl interpreter
 |-
-| '''$/''' || string to be used as input record separator
+| '''$/''' || string to be used as input record separator; default = newline
 |-
-| '''$\''' || string to be used as output record separator
+| '''$&''' || Contains the string matched by the last pattern match
 |-
-| '''$=''' || not sure what this does
+| '''$`''' || The string preceding whatever was matched by the last pattern match, not counting patterns matched in nested blocks that have been exited already.
 |-
-| '''$~''' || not sure what this does
+| '''$'''' || The string following whatever was matched by the last pattern match, not counting patterns matched in nested blockes that have been exited already.
 |-
-| '''$.''' || current record number in input
+| '''$+''' || The last bracket matched by the last search pattern. This is useful if you don't know which of a set of alternative patterns matched.
 |-
-| '''$<u>n</u>''' || used within [[Perl regex|regular expressions]] to indicate that the matched section in parentheses should be used here (first matched parentheses becomes $1, second becomes $2, etc.)
 |}

Woozle: /* Special Variables */ some more vars

2006-03-12T22:27:16Z

Special Variables: some more vars

← Older revision		Revision as of 22:27, 12 March 2006
Line 95:		Line 95:
	\| '''$^X''' \|\| [[filespec]] of the Perl interpreter		\| '''$^X''' \|\| [[filespec]] of the Perl interpreter
	\|-		\|-
	\| '''$/''' \|\| not sure what this does		\| '''$/''' \|\| string to be used as input record separator
			\|-
			\| '''$\''' \|\| string to be used as output record separator
			\|-
			\| '''$=''' \|\| not sure what this does
			\|-
			\| '''$~''' \|\| not sure what this does
			\|-
			\| '''$.''' \|\| current record number in input
	\|-		\|-
	\| '''$<u>n</u>''' \|\| used within [[Perl regex\|regular expressions]] to indicate that the matched section in parentheses should be used here (first matched parentheses becomes $1, second becomes $2, etc.)		\| '''$<u>n</u>''' \|\| used within [[Perl regex\|regular expressions]] to indicate that the matched section in parentheses should be used here (first matched parentheses becomes $1, second becomes $2, etc.)
	\|}		\|}

Woozle: /* File Test Operators */ special variables

2006-03-12T22:17:56Z

File Test Operators: special variables

@@ Line 75: / Line 75: @@
 |-
 | '''-A''' || Number of days since file was last accessed
 |}

← Older revision		Revision as of 17:58, 1 October 2011
Line 7:		Line 7:
	\| '''\b''' \|\| backspace (ctrl-H, 008 decimal)		\| '''\b''' \|\| backspace (ctrl-H, 008 decimal)
	\|-		\|-
	\| '''\c'''~~<~~u>n~~<~~/u> \|\| ctrl-~~<~~u>n~~<~~/u> (e.g. \cj = CTRL-J, i.e. Line Feed)		\| '''\c'''<u>n</u> \|\| ctrl-<u>n</u> (e.g. \cj = CTRL-J, i.e. Line Feed)
	\|-		\|-
	\| '''\e''' \|\| ESC (027 decimal, 033 octal)		\| '''\e''' \|\| ESC (027 decimal, 033 octal)
Line 29:		Line 29:
	\| '''\E''' \|\| ends case conversion started by \L or \U		\| '''\E''' \|\| ends case conversion started by \L or \U
	\|-		\|-
	\| '''\~~<~~nowiki>'~~<~~/nowiki>''' \|\| prints a literal single-quote		\| '''\<nowiki>'</nowiki>''' \|\| prints a literal single-quote
	\|-		\|-
	\| '''\"''' \|\| prints a literal double-quote		\| '''\"''' \|\| prints a literal double-quote
Line 54:		Line 54:
	\| '''/''' \|\| divide \|\| $x'''/'''$y		\| '''/''' \|\| divide \|\| $x'''/'''$y
	\|-		\|-
	\| '''%''' \|\| modulo (remainder) \|\| $x'''%'''$y -&~~amp;~~gt; remainder of x/y		\| '''%''' \|\| modulo (remainder) \|\| $x'''%'''$y -> remainder of x/y
	\|-		\|-
	\| '''''' \|\| exponent \|\| $x''''''$y -&~~amp;~~gt; x~~<~~sup>y~~<~~/sup>		\| '''''' \|\| exponent \|\| $x''''''$y -> x<sup>y</sup>
	\|-		\|-
	\| '''++''' \|\| incrememt \|\| $x++ or ++$x -&~~amp;~~gt; x is incremented by 1		\| '''++''' \|\| incrememt \|\| $x++ or ++$x -> x is incremented by 1
	\|-		\|-
	\| '''--''' \|\| decrement \|\| $x-- or --$x -&~~amp;~~gt; x is decremented by 1		\| '''--''' \|\| decrement \|\| $x-- or --$x -> x is decremented by 1
	\|-		\|-
	\| colspan=3 \|		\| colspan=3 \|
Line 69:		Line 69:
	\| '''!=''' \|\| is different \|\| $x'''!='''$y returns true iff x does not equal y		\| '''!=''' \|\| is different \|\| $x'''!='''$y returns true iff x does not equal y
	\|-		\|-
	\| '''&~~amp;~~lt;''' \|\| is less than \|\| $x'''&~~amp;~~lt;'''$y returns true iff x is smaller than y		\| '''<''' \|\| is less than \|\| $x'''<'''$y returns true iff x is smaller than y
	\|-		\|-
	\| '''&~~amp;~~gt;''' \|\| is more than \|\| $x'''&~~amp;~~gt;'''$y returns true iff x is larger than y		\| '''>''' \|\| is more than \|\| $x'''>'''$y returns true iff x is larger than y
	\|-		\|-
	\| colspan=3 \|		\| colspan=3 \|
Line 89:		Line 89:
	==File Test Operators==		==File Test Operators==
	All operators are used like this:		All operators are used like this:
	-''x'' ~~<~~u>$filename~~<~~/u>		-''x'' <u>$filename</u>
	{\|		{\|
	\|-		\|-
Line 158:		Line 158:
	\| '''$[''' \|\| The index of the first element in an array, and of the first character in a substring.		\| '''$[''' \|\| The index of the first element in an array, and of the first character in a substring.
	\|-		\|-
	\| '''$&~~amp;~~lt;''' \|\| ~~<~~s>username of user running the Perl script~~<~~/s> real user ID of the current process (UNIX/Linux) (may not be very useful for CGI because Apache always executes as the same user)		\| '''$<''' \|\| <s>username of user running the Perl script</s> real user ID of the current process (UNIX/Linux) (may not be very useful for CGI because Apache always executes as the same user)
	\|-		\|-
	\| '''$&~~amp;~~gt;''' \|\| effective user ID of the current process (UNIX/Linux)		\| '''$>''' \|\| effective user ID of the current process (UNIX/Linux)
	\|-		\|-
	\| '''$/''' \|\| string to be used as input record separator; default = newline		\| '''$/''' \|\| string to be used as input record separator; default = newline
Line 182:		Line 182:
	\| '''$?''' \|\| The status returned by the last child process, i.e. pipe close, backtick(``) command or system operator.		\| '''$?''' \|\| The status returned by the last child process, i.e. pipe close, backtick(``) command or system operator.
	\|-		\|-
	\| '''$!''' \|\| If used in a numeric context, yields the current value <span class="plainlinks">[http://www.thepiggybackrider.com/ <span style="color:black;font-weight:normal; text-decoration:none!important; background:none!important; text-decoration:none;/CITATION/">child carrier</span>]</span> of errno, with all the usual caveats. (This means that you shouldn't depend on the value of $! to be anything in particular unless you've gotten a specific error return indicating a system error.) If used in a string context, yields the corresponding sysem error string.		\| '''$!''' \|\| If used in a numeric context, yields the current value of errno, with all the usual caveats. (This means that you shouldn't depend on the value of $! to be anything in particular unless you've gotten a specific error return indicating a system error.) If used in a string context, yields the corresponding sysem error string.
	\|-		\|-
	\| '''$@''' \|\| The Perl syntax error or routine error message from the last eval, do-FILE, or require command. If set, either the compilation failed, or the die function was executed within the code of the eval.		\| '''$@''' \|\| The Perl syntax error or routine error message from the last eval, do-FILE, or require command. If set, either the compilation failed, or the die function was executed within the code of the eval.
Line 211:		Line 211:
	These are associated with the last successful pattern match.		These are associated with the last successful pattern match.
	\|-		\|-
	\| '''$~~<~~u>n~~<~~/u>''' \|\| in the replacement section, indicate that the ~~<~~u>n~~<~~/u>~~<~~sup>th~~<~~/sup> matched section in parentheses should be used here (first matched parentheses becomes $1, second becomes $2, etc., up through $9)		\| '''$<u>n</u>''' \|\| in the replacement section, indicate that the <u>n</u><sup>th</sup> matched section in parentheses should be used here (first matched parentheses becomes $1, second becomes $2, etc., up through $9)
	\|-		\|-
	\| '''$&~~amp;~~''' \|\| Contains the string matched by the last pattern match. ''Introduces CPU/memory overhead for all regex operations in the script; avoid.''		\| '''$&''' \|\| Contains the string matched by the last pattern match. ''Introduces CPU/memory overhead for all regex operations in the script; avoid.''
	\|-		\|-
	\| '''$`''' \|\| The string preceding whatever was matched by the last pattern match, not counting patterns matched in nested blocks that have been exited already. ''Introduces CPU/memory overhead for all regex operations in the script; avoid.''		\| '''$`''' \|\| The string preceding whatever was matched by the last pattern match, not counting patterns matched in nested blocks that have been exited already. ''Introduces CPU/memory overhead for all regex operations in the script; avoid.''

← Older revision		Revision as of 15:13, 26 September 2011
Line 7:		Line 7:
	\| '''\b''' \|\| backspace (ctrl-H, 008 decimal)		\| '''\b''' \|\| backspace (ctrl-H, 008 decimal)
	\|-		\|-
	\| '''\c'''<u>n</u> \|\| ctrl-<u>n</u> (e.g. \cj = CTRL-J, i.e. Line Feed)		\| '''\c'''<u>n</u> \|\| ctrl-<u>n</u> (e.g. \cj = CTRL-J, i.e. Line Feed)
	\|-		\|-
	\| '''\e''' \|\| ESC (027 decimal, 033 octal)		\| '''\e''' \|\| ESC (027 decimal, 033 octal)
Line 29:		Line 29:
	\| '''\E''' \|\| ends case conversion started by \L or \U		\| '''\E''' \|\| ends case conversion started by \L or \U
	\|-		\|-
	\| '''\<nowiki>'</nowiki>''' \|\| prints a literal single-quote		\| '''\<nowiki>'</nowiki>''' \|\| prints a literal single-quote
	\|-		\|-
	\| '''\"''' \|\| prints a literal double-quote		\| '''\"''' \|\| prints a literal double-quote
Line 54:		Line 54:
	\| '''/''' \|\| divide \|\| $x'''/'''$y		\| '''/''' \|\| divide \|\| $x'''/'''$y
	\|-		\|-
	\| '''%''' \|\| modulo (remainder) \|\| $x'''%'''$y -> remainder of x/y		\| '''%''' \|\| modulo (remainder) \|\| $x'''%'''$y -&gt; remainder of x/y
	\|-		\|-
	\| '''''' \|\| exponent \|\| $x''''''$y -> x<sup>y</sup>		\| '''''' \|\| exponent \|\| $x''''''$y -&gt; x<sup>y</sup>
	\|-		\|-
	\| '''++''' \|\| incrememt \|\| $x++ or ++$x -> x is incremented by 1		\| '''++''' \|\| incrememt \|\| $x++ or ++$x -&gt; x is incremented by 1
	\|-		\|-
	\| '''--''' \|\| decrement \|\| $x-- or --$x -> x is decremented by 1		\| '''--''' \|\| decrement \|\| $x-- or --$x -&gt; x is decremented by 1
	\|-		\|-
	\| colspan=3 \|		\| colspan=3 \|
Line 69:		Line 69:
	\| '''!=''' \|\| is different \|\| $x'''!='''$y returns true iff x does not equal y		\| '''!=''' \|\| is different \|\| $x'''!='''$y returns true iff x does not equal y
	\|-		\|-
	\| '''<''' \|\| is less than \|\| $x'''<'''$y returns true iff x is smaller than y		\| '''&lt;''' \|\| is less than \|\| $x'''&lt;'''$y returns true iff x is smaller than y
	\|-		\|-
	\| '''>''' \|\| is more than \|\| $x'''>'''$y returns true iff x is larger than y		\| '''&gt;''' \|\| is more than \|\| $x'''&gt;'''$y returns true iff x is larger than y
	\|-		\|-
	\| colspan=3 \|		\| colspan=3 \|
Line 89:		Line 89:
	==File Test Operators==		==File Test Operators==
	All operators are used like this:		All operators are used like this:
	-''x'' <u>$filename</u>		-''x'' <u>$filename</u>
	{\|		{\|
	\|-		\|-
Line 158:		Line 158:
	\| '''$[''' \|\| The index of the first element in an array, and of the first character in a substring.		\| '''$[''' \|\| The index of the first element in an array, and of the first character in a substring.
	\|-		\|-
	\| '''$<''' \|\| <s>username of user running the Perl script</s> real user ID of the current process (UNIX/Linux) (may not be very useful for CGI because Apache always executes as the same user)		\| '''$&lt;''' \|\| <s>username of user running the Perl script</s> real user ID of the current process (UNIX/Linux) (may not be very useful for CGI because Apache always executes as the same user)
	\|-		\|-
	\| '''$>''' \|\| effective user ID of the current process (UNIX/Linux)		\| '''$&gt;''' \|\| effective user ID of the current process (UNIX/Linux)
	\|-		\|-
	\| '''$/''' \|\| string to be used as input record separator; default = newline		\| '''$/''' \|\| string to be used as input record separator; default = newline
Line 182:		Line 182:
	\| '''$?''' \|\| The status returned by the last child process, i.e. pipe close, backtick(``) command or system operator.		\| '''$?''' \|\| The status returned by the last child process, i.e. pipe close, backtick(``) command or system operator.
	\|-		\|-
	\| '''$!''' \|\| If used in a numeric context, yields the current value of errno, with all the usual caveats. (This means that you shouldn't depend on the value of $! to be anything in particular unless you've gotten a specific error return indicating a system error.) If used in a string context, yields the corresponding sysem error string.		\| '''$!''' \|\| If used in a numeric context, yields the current value <span class="plainlinks">[http://www.thepiggybackrider.com/ <span style="color:black;font-weight:normal; text-decoration:none!important; background:none!important; text-decoration:none;/CITATION/">child carrier</span>]</span> of errno, with all the usual caveats. (This means that you shouldn't depend on the value of $! to be anything in particular unless you've gotten a specific error return indicating a system error.) If used in a string context, yields the corresponding sysem error string.
	\|-		\|-
	\| '''$@''' \|\| The Perl syntax error or routine error message from the last eval, do-FILE, or require command. If set, either the compilation failed, or the die function was executed within the code of the eval.		\| '''$@''' \|\| The Perl syntax error or routine error message from the last eval, do-FILE, or require command. If set, either the compilation failed, or the die function was executed within the code of the eval.
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	These are associated with the last successful pattern match.		These are associated with the last successful pattern match.
	\|-		\|-
	\| '''$<u>n</u>''' \|\| in the replacement section, indicate that the <u>n</u><sup>th</sup> matched section in parentheses should be used here (first matched parentheses becomes $1, second becomes $2, etc., up through $9)		\| '''$<u>n</u>''' \|\| in the replacement section, indicate that the <u>n</u><sup>th</sup> matched section in parentheses should be used here (first matched parentheses becomes $1, second becomes $2, etc., up through $9)
	\|-		\|-
	\| '''$&''' \|\| Contains the string matched by the last pattern match. ''Introduces CPU/memory overhead for all regex operations in the script; avoid.''		\| '''$&''' \|\| Contains the string matched by the last pattern match. ''Introduces CPU/memory overhead for all regex operations in the script; avoid.''
	\|-		\|-
	\| '''$`''' \|\| The string preceding whatever was matched by the last pattern match, not counting patterns matched in nested blocks that have been exited already. ''Introduces CPU/memory overhead for all regex operations in the script; avoid.''		\| '''$`''' \|\| The string preceding whatever was matched by the last pattern match, not counting patterns matched in nested blocks that have been exited already. ''Introduces CPU/memory overhead for all regex operations in the script; avoid.''