Options for Perl Regular Expressions
Regular expressions can have options (also known as flags) that modify their behavior. Each engine supports a different set of options.
| Option | Description | Backend value | Portable value |
|---|
| m | Multiline | multiline | multiline |
| s | Single line | dotall | (not portable) |
| i | Case-insensitive | ignorecase | ignorecase |
| x | Extended with whitespace and comments | comment | comments |
| p | Preserve matched strings | p | (not portable) |
| g | Global match | global | (not portable) |
| c | Keep current position | c | (not portable) |
| a | Use ASCII charset rules | a | (not portable) |
| d | Use default charset rules | d | (not portable) |
| l | Use locale charset rules | l | (not portable) |
| u | Use Unicode charset rules | u | (not portable) |
When m and s together, . matches any char including newlines but ^ and $ match lines.