Steven J Lamb wrote:
what I am looking for is information on how to use grep in the following
way. I want to do essentially this
grep (string1|string2|string3) filename
I would use this to search filename for either string1, string2 or
string 3 instances
I realize I could do the following but would like to use it as one grep
statement as I believe it should be more efficient.
tmp;
grep string1 filename >>tmp;
grep string2 filename >>tmp;
grep string3 filename >>tmp
as this would be defined in a normal regular expression. grep claims to
be able to use this functionality as best I can tell ... it is
documented in the man page and it says
Two regular expressions may be joined by the infix operator |; the
resulting regular expression matches
any string matching either subexpression.
I have not been able to find an example of this anywhere and have tried
several forms of the syntax but no luck. my command interpreter keeps
trying to use the pipe instead of letting grep have it.
any one have any thoughts
thanks
Steven Lamb
Use egrep:
egrep "(string1|string2|string3)" filename
does exactly this.
--
Joachim Backes <joachim.backes@xxxxxxxxxxxxxx>
Registered Linux user #407492
University of Kaiserslautern,Computer Center [RHRK],
Systems and Operations, High Performance Computing,
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