[SOLVED] grep weird behaviour in linux command line

Issue

I have a file test.txt which contains this text data

# cat test.txt
*@=>*@

if I use grep to check if the string is in the file using this way

# grep "*@=>*@" test.txt
#

it returns nothing..

while if I grep a partial string search

# grep "*@=>" test.txt
# *@=>*@

it works correctly ..

Why in the first case do grep return nothing ?

Solution

The asterisk is special to grep, it means "the previous token is repeated zero or more times". So >* would match an empty string or > or >> etc.

To match an asterisk, backslash it in the pattern:

grep '\*@=>\*@' test.txt

(The first asterisk follows no token, so the backslash is optional.)

Answered By - choroba