Shell Programming and Scripting

Code:

dt="11/20/12"
echo $dt
11/20/12
new_dt=`echo $dt | awk -F'/' '{ print "20"$3"/"$2"/"$1 }' | sed 's#\/#\\\/#g'`
echo $new_dt
2012\/20\/11
nawk '/'"$new_dt"'/,EOF { print $0 }' datefiltertestfile.txt

2012/20/11 :12.00 AM some other data
some line without dates
some more lines without dates
2012/20/11 :12.01 AM some more data
....
.......

Not a single match attempt in an OP post has actually used or required a pattern. They've all been literal matches. If that's always going to be the case, I would recommend using a simpler, less error-prone literal match in favor of regular expression pattern matching.

If the date is the first text on a line and is followed by whitespace, as is the case in the samples:

Code:

awk '$1==x,0' x=11/20/12

For a more general solution which matches the string at any location in a line:

Code:

awk 'index($0,x),0' x=11/20/12

Regards,
Alister