Regular Expressions/Basic Regular Expressions

Basic Regular Expressions: Note that particular implementations of regular expressions interpret the backslash symbol differently in front of some of the metacharacters. For example, egrep and perl interpret unbackslashed parentheses and vertical bars as metacharacters, reserving the backslashed versions to mean the literal characters themselves. Old versions of grep did not support the pipe alternation operator.

Many ranges of characters depend on the chosen locale setting. For example, in some settings letters are organized as abc..yzABC..YZ, while in some they are organized as aAbBcC..yYzZ.

The ../Posix Basic Regular Expressions/ syntax provided extensions for consistency between utility programs such as grep, sed and awk. These extensions are not supported by some traditional implementations of Unix tools.

Use in Tools
Tools and languages that utilize this regular expression syntax include: TBD