topic Re: Regular Expression Question in Operating System - HP-UX

Regular Expression Question

Mihails Nikitins — Fri, 06 Sep 2002 14:45:27 GMT

Hi,

Please help me in composing very simple regular expression.

I'm parsing e-mail box and there is a need to distinguish two "From" lines

From root@host.com Fri Sep 6 18:32:25 2002
and
From: root@host.com

Both lines are retrieved by expression /From/
I'd like to get line with word 'From' followed by white space. The white space is my problem.

Thanks and points in advance!

BR,
Mihails

Re: Regular Expression Question

Rodney Hills — Fri, 06 Sep 2002 14:47:10 GMT

Unde perl you would use-

/^From:?\s*(.*)/

Then $1 would contain text

-- Rod Hills

Re: Regular Expression Question

Charles McCary — Fri, 06 Sep 2002 14:50:17 GMT

cat mail.box | grep "From "

or

Cat mail.box | grep From | grep -v "From:"

I think this is what you wanted?

c

Re: Regular Expression Question

Rodney Hills — Fri, 06 Sep 2002 14:52:23 GMT

How is white space being a problem?

grep "From " file

doesn't work?

-- Rod Hills

Re: Regular Expression Question

Shannon Petry — Fri, 06 Sep 2002 14:54:27 GMT

I used grep relatively easily

grep "From\ "
will get the word "From" followed by a whitespace.
grep "From:" will grabe other
if the whitespace is a tab, then
grep "From\ "
where the whitespace above is a tab.

This should not require really a regular expression to get, but the same principles exist.

regards,
Shannon

Re: Regular Expression Question

Hai Nguyen_1 — Fri, 06 Sep 2002 14:55:23 GMT

Mihails,

Try /From / (there is a space right behind From.)

Hai

Re: Regular Expression Question

H.Merijn Brand (procura — Fri, 06 Sep 2002 14:57:22 GMT

/^From[^:]/

in most applications (awk, sed, perl

Charles, please unlearn 'cat':

grep /regex/
is both faster and more efficient than

cat file | grep /regex/

and as a bonus you'll hit maxproc less often :)

Re: Regular Expression Question

James R. Ferguson — Fri, 06 Sep 2002 14:58:04 GMT

Hi:

Try:

awk '/From[ ]/ {print}'

Regards!

...JRF...

Re: Regular Expression Question

John Palmer — Fri, 06 Sep 2002 15:15:51 GMT

Try:
/From[|]/

Where is a single space character and a single tab.

Regards,
John

Re: Regular Expression Question

John Palmer — Fri, 06 Sep 2002 15:23:52 GMT

Another one is:

/From[:space:]/

See man 5 regexp

Regards,
John

Re: Regular Expression Question

Mihails Nikitins — Tue, 10 Sep 2002 10:03:25 GMT

Thanks for your replies, I wanted nice regular expression with brackets, not grep. Even do not ask me why simplier solutions did not work. There was a mystic problem located between the seat and keyboard. :-)

BR,
Mihails