O'Reilly logo

Unix in a Nutshell, 4th Edition by Arnold Robbins

Stay ahead with the world's most comprehensive technology and business learning platform.

With Safari, you learn the way you learn best. Get unlimited access to videos, live online training, learning paths, books, tutorials, and more.

Start Free Trial

No credit card required

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. The following tables show some example patterns.

Pattern

What does it match?

bag

The string bag.

^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.

b[aeiou]g

Second letter is a vowel.

b[^aeiou]g

Second letter is a consonant (or uppercase or symbol).

b.g

Second letter is any character.

^...$

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.

"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 as previous, 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, either lower- or uppercase.

[^0-9A-Za-z]

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

[^[:alnum:]]

Same, using ...

With Safari, you learn the way you learn best. Get unlimited access to videos, live online training, learning paths, books, interactive tutorials, and more.

Start Free Trial

No credit card required