using grep in script

[Dave Chamberlin]

In the Posix or Bourne shell, I wish to extract lines from a file with strings like "Jul 15". On the command line I can do:
cat myfile | grep "Jul 15"
and this works. When I try this in a script like:
cat myfile | grep "Jul 18"
it works, but when I try to use a variable I can't get the script to work:

set ""Jul 15""
echo $1
cat myfile | grep $1

even though the echo gives "Jul 15" . Also the script:
cat myfile | grep $1
will not work for "Jul 15" as the input argument. I cannot get a script to work with any command line argument that has more than a single string. Does someone know how to do this?

[Rick Garland]

In your script try the following:

DATE=`date %'+b +d'`
grep $DATE

I am assuming that you are wanting something to look for dates. This is for the current date.

[RikTytgat]

Hi,

Rick is right. The catch is in the difference between single and double quotes. This is sometimes confusing when writing shell scripts.

Bye,
Rik

[RikTytgat]

Hi,

Supplement:

When you like to pass a command line argument that contains whitespace as a single positional argument, enclose it in quotes.

Like:
myscript "This is a test"

$1 will contain the string "This is a test" (without the quotes).

If you want to use it as an argument to yet another command which should consider it as 1 positional argument, you should do

grep "$1"

Bye again,
Rik

[Dave Chamberlin]

It works fine if grep "$1" used instead of grep $1. Thanks for the help.