egrep—searches a file for a pattern using full regular expressions
egrep [ –bchilnsv ] [ –e special–expression ][ –f filename ]
[ strings ] [ filename ... ]
egrep (expression grep) searches files for a pattern of characters and prints all lines that contain that pattern. egrep uses full regular expressions (expressions with string values that use the full set of alphanumeric and special characters) to match the patterns.
Example A.23.
1 egrep 'Tom|John' datafile
2 egrep '^ [A-Z]+' file
EXPLANATION
Displays all lines in datafile containing the pattern either Tom or John. Displays all lines starting with one or more uppercase letters.
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