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.
Pattern |
What does it match? |
bag |
The string |
^bag |
|
bag$ |
|
^bag$ |
|
[Bb]ag |
|
b[aeiou]g |
|
b[^aeiou]g |
|
b.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* |
|
“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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