Examples of Searching

When used with grep or egrep, regular expressions should be surrounded by quotes. (If the pattern contains a $, you must use single quotes; e.g., ' pattern '.) When used with ed, ex, sed, and awk, regular expressions are usually surrounded by /, although (except for awk) any delimiter works. Tables 6-6 through Table 6-9 show some example patterns.

Table 6-6. General search patterns

Pattern

What does it match?

bag

The string bag anywhere in the line

^bag

bag at the beginning of the line.

bag$

bag at the end of the line.

^bag$

bag as the only word on the line.

[Bb]ag

Bag or bag anywhere in the line.

b[aeiou]g

b, a vowel, and g.

b[^aeiou]g

b, a consonant (or uppercase or symbol), and g.

b.g

b, any character, and g.

^...$

Any line containing exactly three characters.

^\.

Any line that begins with a dot.

^\.[a-z][a-z]

Same, followed by two lowercase letters (e.g., troff requests).

^\.[a-z]\{2\}

Same as previous; ed, grep, and sed only.

^\[^.]

Any line that doesn’t begin with a dot.

bugs*

bug, bugs, bugss, etc, anywhere on the line

“word”

A word in quotes.

“*word"*

A word, with or without quotes.

[A-Z][A-Z]*

One or more uppercase letters.

[A-Z]+

Same; egrep or awk only.

[[:upper:]]+

Same; POSIX egrep or awk.

[A-Z].*

An uppercase letter, followed by zero or more characters.

[A-Z]*

Zero or more uppercase letters.

[a-zA-Z]

Any letter.

[^0-9A-Za-z]

Any symbol or space (not a letter or a number).

[^[:alnum:]]

Same, ...

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