Metacharacters, Listed by Linux Program (Linux in a Nutshell, 3rd Edition)

9.2. Metacharacters, Listed by Linux Program

Some metacharacters are valid for one program but not for another. Those that are available to a given program are marked by a bullet () in the following table. Notes are provided after the table, and full descriptions of metacharacters are in the following section.

Symbol	ed	vi	sed	awk	grep	egrep	Action
`.`							Match any character (can match newline in gawk).
`*`							Match zero or more preceding.
`^`							Match beginning of line or string.
`$`							Match end of line or string.
`\`							Escape character following.
`[]`							Match one from a list or range.
``							Store pattern for later replay.
`\`n							Reuse matched text stored in nth .
`{}`							Match a range of instances.
`\{\}`							Match a range of instances.
`\<\>`							Match word's beginning or end.
`+`							Match one or more preceding.
`?`							Match zero or one preceding.
`\|`							Separate choices to match.
`()`							Group expressions to match.

On some Linux systems, grep is a link to egrep, so whenever you run grep you actually get egrep behavior.

In ed, vi, and sed, when you perform a search-and-replace (substitute) operation, the metacharacters in this table apply to the pattern you are searching for but not to the string replacing it.

In awk, {} is specified in the POSIX standard and is supported by gawk if you run it with the -Wre-interval option.

In ed, vi, and sed, the following additional metacharacters are valid only in a replacement pattern:

Symbol	ex	sed	ed	Action
`\`				Escape character following.
`\`n				Reuse matched text stored in nth .
`&`				Reuse previous search pattern.
`~`				Reuse previous replacement pattern.
`\e`				Turn off previous \L or \U.
`\E`				Turn off previous /L or /U.
`\l`				Change single following character to lowercase.
`\L`				Change following characters to lowercase until /E encountered.
`\u`				Change single following character to uppercase.
`\U`				Change following characters to uppercase until \E encountered.