grepping for period . in file name ? ie grep .

bobk544 · #1 (**permalink**) 11-30-2007

hello,
this works ok where i'm greping for the ./ :

HTML Code:

export m1="./xyz.java "
echo  $m1 | grep ./ > /dev/null
if [ $? = 0 ]; then
     echo $m1
fi

but this doesn't where i'm just greping for the period . and i also tried .\

HTML Code:

export m1="xyz.java "
echo  $m1 | grep . > /dev/null
if [ $? = 0 ]; then
     echo $m1
fi

any ideas on how to wrap the . so it's not treated as a file reference or parm or whatever is happening there please?

thanks
bk

bobk544 · #2 (**permalink**) 11-30-2007

ok i think i have it i put the period in a variable ie:

grep $p

thanks
bk

$antaclau$ · #3 (**permalink**) 11-30-2007

or simply try putting the searching pattern withing quotes

echo $m1 | grep "." > /dev/null

Tada
$anta

drl · #4 (**permalink**) 11-30-2007

Hi.

In regular expressions with grep, the "." (period, dot, full-stop) matches any single character (except newline), so you will need to provide an escape that grep will encounter, thereby effectively removing the normal "magic" of the ".".
Use

Code:

"\."

(with quotes) as that escaped sequence.

Here's an example:

Code:

#!/usr/bin/env sh

# @(#) s1       Demonstrate dot with grep regular expressions.

set -o nounset
echo

debug=":"
debug="echo"

## Use local command version for the commands in this demonstration.

echo "(Versions displayed with local utility \"version\")"
version >/dev/null 2>&1 && version bash my-nl grep

echo

# Create data file data1

cat >data1 <<EOF
Hello, world.
Two, no dot: Hello, world (this line should not be matched)
Next line empty (this line and the next should not be matched)

Next line just a dot.
.
Last line here.
EOF

echo
echo " Numbered input file:"
my-nl data1

echo
echo " grep with just a dot:"
grep -n . data1

echo
echo " grep with escaped dot, but not quoted:"
grep -n \. data1

echo
echo " grep with escaped dot, double quotes:"
grep -n "\." data1

exit 0

which produces:

Code:

% ./s1

(Versions displayed with local utility "version")
GNU bash 2.05b.0
my-nl (local) 296
grep (GNU grep) 2.5.1


 Numbered input file:

==> data1 <==

  1 Hello, world.
  2 Two, no dot: Hello, world (this line should not be matched)
  3 Next line empty (this line and the next should not be matched)
  4
  5 Next line just a dot.
  6 .
  7 Last line here.

 grep with just a dot:
1:Hello, world.
2:Two, no dot: Hello, world (this line should not be matched)
3:Next line empty (this line and the next should not be matched)
5:Next line just a dot.
6:.
7:Last line here.

 grep with escaped dot, but not quoted:
1:Hello, world.
2:Two, no dot: Hello, world (this line should not be matched)
3:Next line empty (this line and the next should not be matched)
5:Next line just a dot.
6:.
7:Last line here.

 grep with escaped dot, double quotes:
1:Hello, world.
5:Next line just a dot.
6:.
7:Last line here.

To see the details, run as:

Code:

sh -vx s1

Best wishes ... cheers, drl

gus2000 · #5 (**permalink**) 11-30-2007

You must either escape the special characters, or tell grep use match ordinary strings instead of regex patterns:

Code:

grep "aaa\.bbb" myfile.txt
grep -F "aaa.bbb" myfile.txt

bobk544 · #6 (**permalink**) 12-01-2007

wow thanks all this is one awesome forum, happy weekend all!

More UNIX and Linux Forum Topics You Might Find Helpful
Thread	Thread Starter	Forum	Replies	Last Post
Grepping the last 30 minutes of a log file...	jtelep	Shell Programming and Scripting	2	03-06-2008 12:27 AM
Loop and grepping into a file	skotapal	Shell Programming and Scripting	3	08-26-2002 10:28 PM
grepping the first 3 characters from a file	rachael	UNIX for Dummies Questions & Answers	2	10-15-2001 03:33 PM
grepping the first 3 characters from a file	g-e-n-o	UNIX for Dummies Questions & Answers	2	10-15-2001 07:11 AM
Deleting a File with an Erroneous Period	PLF	UNIX for Dummies Questions & Answers	3	08-09-2001 03:04 AM

Thread Tools	Search this Thread
Show Printable Version Email this Page	Search this Thread: Advanced Search
Display Modes	Rate This Thread
Switch to Linear Mode Hybrid Mode Switch to Threaded Mode	Rate This Thread:


	Powered by