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 | ${^CHILD_ERROR_NATIVE} | Native status returned by the last pipe close, backtick (`` ) command, successful call to wait() or waitpid(), or from the system() operator |
| | IO and Separators$. | 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' | ${^RE_TRIE_MAXBUF} | Control memory allocations for RE optimizations for large alternations |
| | Perl Status Info$] | 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 ArgsARGV | 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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