Linux in a Nutshell, Fifth Edition

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Chapter 7: Pattern Matching

This is the Title of the Book, eMatter Edition

Copyright © 2006 O’Reilly & Associates, Inc. All rights reserved.

Examples of Searching and Replacing

The examples in the following table show the metacharacters available to sed or

ex. Note that ex commands begin with a colon. A space is marked by a ❒; a tab is

marked by a tab.

\

[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 POSIX character class.

egrep or awk pattern What does it match?

[567] One of the numbers 5, 6, or 7.

five|six|seven One of the words five, six, or seven.

80[2-4]?86 8086, 80286, 80386, or 80486.

80[2-4]?86|(Pentium(-III?)?) 8086, 80286, 80386, 80486, Pentium, Pentium-II, or Pentium-III.

compan(y|ies) company or companies.

ex or vi pattern What does it match?

\<the Words like theater or the.

the\> Words like breathe or the.

\<the\> The word the.

ed, sed or grep pattern What does it match?

0\{5,\} Five or more zeros in a row.

[0-9]\{3\}-[0-9]\{2\}-[0-9]\{4\} U.S. Social Security number (nnn-nn-nnnn).

\(why\).*\1 A line with two occurrences of why.

\([[:alpha:]_][[:alnum:]_.]*\) = \1; C/C++ simple assignment statements.

Command Result

s/.*/( & )/ Redo the entire line, but add spaces and parentheses.

s/.*/mv & &.old/ Change a wordlist (one word per line) into mv commands.

/^$/d Delete blank lines.

:g/^$/d Same as previous, ...