Cheatography
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Special Vars Quick Reference
Standard
$_ |
The default or implicit variable |
@_ |
Subroutine parameters |
$a $b |
Sort comparison routine variables |
@ARGV |
The command-line args |
ID's and Process Information
$$ |
Process ID |
$< |
Real user id of process |
$> |
Effective user id of process |
$( |
Real group id of process |
$) |
Effective group id of process |
$0 |
Program name |
$^O |
Operating System name |
Encoding
${^ENCODING} |
The object reference to the Encode object, used to convert the source code to Unicode |
${^OPEN} |
Internal use: \0 separated Input / Output layer information |
${^UNICODE} |
Read-only Unicode settings |
${^UTF8CACHE} |
State of the internal UTF-8 offset caching code |
${^UTF8LOCALE} |
Indicates whether UTF8 locale was detected at startup |
Miscellaneous
@F |
Autosplit (-a mode) recipient |
@INC |
List of library paths |
%INC |
Keys are filenames, values are paths to modules included via use, require, or do |
%ENV |
Hash containing current environment variables |
%SIG |
Signal handlers |
$[ |
Array and substr first element (Deprecated!) |
Status Reporting
$? |
Child error. Status code of most recent system call or pipe |
$! |
Operating System Error. (What just went 'bang'?) |
$^E |
Extended Operating System Error (Extra error explanation) |
$@ |
Eval error |
${^CHILD_ERROR_NATIVE} |
Native status returned by the last pipe close, backtick (`` ) command, successful call to wait() or waitpid(), or from the system() operator |
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IO and Separators
$. |
Current line number (or record number) of most recent filehandle |
$/ |
Input record separator |
$| |
Output autoflush. 1=autoflush, 0=default. Applies to currently selected handle |
$, |
Output field separator (lists) |
$\ |
Output record separator |
$" |
Output list separator. (interpolated lists) |
$; |
Subscript separator. (Use a real multidimensional array instead) |
Regular Expressions
$<digit> |
Regexp parenthetical capture holders |
$& |
Last successful match (degrades performance) |
${^MATCH} |
Similar to $& without performance penalty. Requires /p modifier |
$` |
Prematch for last successful match string (degrades performance) |
${^PREMATCH} |
Similar to $` without performance penalty. Requires /p modifier |
$' |
Postmatch for last successful match string (degrades performance) |
${^POSTMATCH} |
Similar to $' without performance penalty. Requires /p modifier |
$+ |
Last paren match |
$^N |
Last closed paren match (last submatch) |
@+ |
Offsets of ends of successful submatches in scope |
@- |
Offsets of starts of successful submatches in scope |
%+ |
Like @+, but for named submatches |
%- |
Like @-, but for named submatches |
$^R |
Last regexp (?{code}) result |
${^RE_DEBUG_FLAGS} |
Current value of regexp debugging flags. See use re 'debug' |
${^RE_TRIE_MAXBUF} |
Control memory allocations for RE optimizations for large alternations |
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Perl Status Info
$] |
Old: Version and patch number of perl interpreter. Deprecated |
$^C |
Current value of flag associated with -c switch |
$^D |
Current value of debugging flags |
$^F |
Maximum system file descriptor |
$^I |
Value of the -i (inplace edit) switch |
$^M |
Emergency Memory pool |
$^P |
Internal variable for debugging support |
$^R |
Last regexp (?{code}) result |
$^S |
Exceptions being caught. (eval) |
$^T |
Base time of program start |
$^V |
Perl version |
$^W |
Status of -w switch |
${^WARNING_BITS} |
Current set of warning checks enabled by use warnings; |
$^X |
Perl executable name |
${^GLOBAL_PHASE} |
Current phase of the Perl interpreter |
$^H |
Internal use only: Hook into Lexical Scoping |
%^H |
Internaluse only: Useful to implement scoped pragmas |
${^TAINT} |
Taint mode read-only flag |
${^WIN32_SLOPPY_STAT} |
If true on Windows stat() won't try to open the file |
Command Line Args
ARGV |
Filehandle iterates over files from command line (see also <>) |
$ARGV |
Name of current file when reading <> |
@ARGV |
List of command line args |
ARGVOUT |
Output filehandle for -i switch |
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