Need help stripping statement from text file, ksh: sed awk?
 

This is my first time to this site, so go easy on me.

I'm writing a Korn Script that clears out the NO_HW entries from an ioscan. The script takes the output of the ioscan and places into a text file. The text file is reduced to only the lines with "NO_HW" on them.

Example:
I am trying to strip out EVERYTHING except the H/W path.

Example:
So that the text file will look like this:

..and so on. So I can use the rmsf -H 0/3/0/0/0/0.0.21.11.0 command on each H/W Path and remove it.

The command needs to be pretty versatile as the H/W path could be just about anything.

I was thinking this could probably be done with sed or maybe awk but I'm not very proficient in those. Thanks.

No need for anything as fancy as sed or awk.

cut -f3 file.txt

This is assuming the fields are separated by tabs. If they're spaces you'll have to add '-d " "' and change the -f number to match the column you want.

Although "David the H." has an easy method, it fails if the column number ever changes. A less fragile approach is
awk is able to handle an arbitrary number of spaces between columns.

Another approach would be to use sed to replace the spaces with commas, and then use cut:
NOTE: The sed expression has two spaces before the asterisk. That tells sed to match one or more spaces.

Moin,

Why do you use stdin redirect? awk is able to read from files given as command line argument.

Again: Why the redirect? The sed is also (like the majority of unix commands) able to retrieve filenames from the command line.

In the second example I'd prefer to let sed do the whole work. No need for cut:
If you want to catch spaces and tabs:
Jan

Habit.

Again, habit.

Not very readable.

Even less readable.

Yup, I fully agree, lines like that make me sick.

Moin,

*habit*, *not readable*, *makes me sick* - strange. I'd think, that efficiency in scripting should be a part of one's judgement too. Your awk solution is o.k., your sed / cut not, it's a waste of resources. Your *habit* to use redirect makes things more difficult to understand (unnecessary redirects and cat's are like an epidemic in my opinion!).

I only wanted to show, how sed can be used to do the whole work in the second example - if one doesn't understand the line, he should be able to ask. It's a simple basic regular expression, nothing high sophisticated.

Jan

The overhead of reading a file from stdin versus opening the file directly is negligible (long.txt is 70007 lines):
It actually took longer for the version that specified the file name, but I would have to run each command at least 100 times and average the results for us to do a fair comparison.

Let us see how long the sed-plus-cut solution takes
Much less efficient. So why would I suggest it? If the comma-separated data is saved, then cut can be reused. Let us see how well that works
So cut is much more efficient than awk when given well formatted input.

Many would disagree with you. It really comes down to a religious debate.

The problem with those regular expressions you posted is that they are hard to decipher. Someone who writes a script using them may come back in a week and forget what they do. Sometimes script writers like to sacrifice efficiency for clarity.