[SOLVED] I need an awk statement that will look for the home directory and comment it out.

Thaidog · 04-14-2012, 06:41 PM

I need an awk statement that will look for the home directory and comment it out in fstab. The reason is we have multiple ways of defining the device path for differt servers so sed will not work all the time. Does anybody know a simple way to do this with awk?

sycamorex · 04-14-2012, 07:04 PM

What are those multiple ways? It's hard to say anything without knowing what you mean.

sycamorex · 04-14-2012, 07:06 PM

Sorry if I'm missing something but why wouldn't it work?

Code:

sed '/home/ s/^/#/' /etc/fstab

uhelp · 04-14-2012, 07:28 PM

if "sed" does not work reliable how can "awk" do?
Here is a bash only solution:

Code:

while read dev mountpoint dummy;
do
    if [[ $mountpoint = "/home" ]] ; then
        printf "#$dev $mountpoint $dummy\n" > fstab.new
        continue ;
    fi  
    printf "$dev $mountpoint $dummy\n" > fstab.new  ;
done < fstab
mv fstab.new fstab

Thaidog · 04-14-2012, 07:42 PM

Quote:

Originally Posted by sycamorex

What are those multiple ways? It's hard to say anything without knowing what you mean.

The problem is that it could be mounted by path, uuid or label so a simple sed option will not work for all instances. If we can use awk to search the second feild it would work to keep the script working with mount styles.

sycamorex · 04-14-2012, 07:44 PM

Quote:

Originally Posted by Thaidog

The problem is that it could be mounted by path, uuid or label so a simple sed option will not work for all instances. If we can use awk to search the second feild it would work to keep the script working with mount styles.

Ok, but how can you identify the second column of the right row if the naming conventions vary?

Thaidog · 04-14-2012, 10:04 PM

Quote:

Originally Posted by sycamorex

Ok, but how can you identify the second column of the right row is the naming conventions vary?

No the second column is the mount point /tmp, /home, ... etc - so that always stays the same... the first column is what is goofy.

grail · 04-15-2012, 06:16 AM

Hence if you have a common item then either sed or awk will both work fine:

Code:

sed -i '/\/home/s/^/#/' fstab

awk '$2 == "/home"{$0 = "#"$0}{print > FILENAME}' fstab

As such an important file I am guessing you will test with example prior to implementation

sycamorex · 04-15-2012, 06:21 AM

Quote:

Originally Posted by Thaidog

No the second column is the mount point /tmp, /home, ... etc - so that always stays the same... the first column is what is goofy.

Yes, that's right. So either I'm really missing something or sed or awk are just the right tools for that. See grail's or my sed examples above.

David the H. · 04-16-2012, 12:21 AM

You know, instead of just giving vague descriptions and making people guess at your exact requirements, you could post an actual example of what you have, along with any conditions or variations that could be encountered, and save everyone some time.

How To Ask Questions The Smart Way

And as demonstrated you shouldn't assume the use of any specific solution (at least not without a clear reason to do so). Focus on what you want to accomplish, not how you think it should be done.

grail · 04-16-2012, 01:02 AM

@David - couldn't agree with you more, in fact I think it should be a provision of joining the site that you need to have read the whole thing and agreed to having done so prior to
account activation.

Thaidog · 04-16-2012, 06:16 AM

Quote:

Originally Posted by grail

Hence if you have a common item then either sed or awk will both work fine:

Code:

sed -i '/\/home/s/^/#/' fstab

awk '$2 == "/home"{$0 = "#"$0}{print > FILENAME}' fstab

As such an important file I am guessing you will test with example prior to implementation

The awk statement works well thanks for your help.

David the H. · 04-17-2012, 06:48 AM

Incidentally, I want to apologize for coming across as a bit harsh in my last post. I was a bit tired, stressed out, and rushed for time yesterday.

I hope you'll take my comment as a bit of friendly advice, rather than a rebuke. Remember, it helps you to get better answers too!