Very Computer

by **waw..** » Thu, 23 Mar 2000 04:00:00

I need help with grep. A korn shell script I'm modifying uses a grep
with a -e option. The grep on our solaris 2.6 workstation does not
list -e as an option. In over versions of grep, what does the -e
option do. WHat equivalent do I use in Solaris?

Here is example code:
grep -e Error -e Warning $logfiles

Should I be using egrep?

Thanks,
Randy

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by **Barry Margoli** » Fri, 24 Mar 2000 04:00:00

>I need help with grep. A korn shell script I'm modifying uses a grep
>with a -e option. The grep on our solaris 2.6 workstation does not
>list -e as an option. In over versions of grep, what does the -e
>option do. WHat equivalent do I use in Solaris?

RTFM:

/usr/xpg4/bin/grep
The following options are supported for /usr/xpg4/bin/grep
only:

-e pattern_list
Specify one or more patterns to be used dur-
ing the search for input. Patterns in
pattern_list must be separated by a NEWLINE
character. A null pattern can be specified
by two adjacent newline characters in
pattern_list. Unless the -E or -F option is
also specified, each pattern will be treated
as a basic regular expression. Multiple -e
and -f options are accepted by grep. All of
the specified patterns are used when matching
lines, but the order of evaluation is
unspecified.

GNU grep also supports this.

Quote:>Here is example code:
> grep -e Error -e Warning $logfiles

>Should I be using egrep?

You could:

egrep 'Error|Warning' $logfiles

But if you needed to protect patterns beginning with '-', you would have to
use a version of grep that supports -e.

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by **Douglas Stetn** » Fri, 24 Mar 2000 04:00:00

>>Here is example code:
>> grep -e Error -e Warning $logfiles

>>Should I be using egrep?

>You could:

>egrep 'Error|Warning' $logfiles

>But if you needed to protect patterns beginning with '-', you would have to
>use a version of grep that supports -e.

Not true (even though it does not appear that he needs patterns
beginning with '-' from the above).

egrep -- '-pattern|other_pattern' filename

will work just fine.

--
Douglas G. Stetner Senior UNIX Support Engineer

My opinions are my own Wollongong, Australia

by **Ken Pizzi** » Fri, 24 Mar 2000 04:00:00

On 23 Mar 2000 01:07:10 GMT,

>>But if you needed to protect patterns beginning with '-', you would have to
>>use a version of grep that supports -e.

>Not true (even though it does not appear that he needs patterns
>beginning with '-' from the above).

>egrep -- '-pattern|other_pattern' filename

>will work just fine.

Well, that presumes that your egrep understands the "--" option,
which isn't true for 15-year old versions of egrep.

The use of a leading hyphen in an RE actually isn't a problem
for either egrep or plain grep:
egrep '(-)pattern|other_pattern' filename
and
grep '[-]pattern' filename
both work just fine. (Yes, the grep approach would also work
with egrep; I just wanted to show different mechanisms.)

The "-e" option to fgrep is older than the use of "--" to
terminate option processing, so I'd be a little suprised if one
had an implementation of [ef]?grep which understood "--" but
not "-e".

--Ken Pizzini

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