Re: [Help-bash] something about "find"

[Greg Wooledge]

On Thu, Dec 29, 2011 at 10:41:53PM +0800, lina wrote:
> I tried
> 
> $ grep -e "7.9" -e "2.4" -e "4.2" -e "12.2" */*
> 
> ...
> lots of nonsense results out like
> ...
> s100a9/s100a9.log:Package: natmove 2009/04/20 v1.1 Automatic citation 
> moving with natbib

grep knows 3 different kinds of patterns: Basic Regular Expressions (BRE),
Extended Regular Expressions (ERE), and plain strings.  By default, grep
uses BRE, and in BRE syntax, the "." is a single-character wildcard; that
is, it matches any single character in the input.

In this case, the grep for BRE pattern "4.2" matched the "4/2" in the
datestamp.

If you want grep to match only literal periods, you must either tell grep
to use plain strings (with the -F option), or write an appropriate BRE
pattern ('4\.2' and so on).  The -F option would be much cleaner here.