Bash commands putting out extra information which results into issues with scripts

Question

Okay, hopefully I can explain this correctly as I have no idea what's causing this or how to resolve this.

For some reason bash commands (on a CentOS 6.x server) are displaying more information than "normally" and that causes issues with certain scripts. I have no clue if there is a name for this, but hopefully someone knows a solution for this.

First example.

Correct / good server:

[root@goodserver ~]# vzctl enter 3567
entered into CT 3567
[root@example /]#

(this is the correct behaviour)

Incorrect / bad server:

[root@badserver /]# vzctl enter 3127
Entering CT
entered into CT 3127
Open /dev/pts/0
           [root@example /]#

With the "bad" server it will display more information as usual, like:

• Entering CT
• Open /dev/pts/0

It's like it parsing extra information on what it's doing.

Ofcourse the above is purely something cosmetic, however with several bash scripts we use, these issues are really issues.

A part of the script we use, uses the following command (there are more, but this is mainly a example of what's wrong):

 DOMAIN=`vzctl exec $VEID 'hostname -d'`

The result of the above information is parsed in /etc/named.conf.

On the GOOD server it would be added in the named.conf like this:

zone "example.com" {
    type master;
    file "example.com";
    allow-transfer {
            200.190.100.10;
            200.190.101.10;
            common-allow-transfer;
    };
};

The above is correct.

On the BAD server it would be added in the named.conf like this:

zone "Executing command: hostname -d
example.com" {
    type master;
    file "Executing command: hostname -d
example.com";
    allow-transfer {
            200.190.100.10;
            200.190.101.10;
            common-allow-transfer;
    };
};

So it's add stuff of the action it does, in this example "Executing command: hostname -d"

Another example here when I run the command on a good server and on the bad server.

Bad server:

[root@bad-server /]# DOMAIN=`vzctl exec 3333 'hostname -d'`
[root@bad-server /]# echo $DOMAIN
Executing command: hostname -d example.com

Good server:

[root@good-server ~]# DOMAIN=`vzctl exec 4444 'hostname -d'`
[root@good-server ~]# echo $DOMAIN
example.com

My knowledge is limited, but I have tried several things checking rsyslog and the grub.conf, but nothing seems out of the ordinary.

I have no clue why it's displaying the extra information.

Probably it's something simple / stupid, but I have been trying to solve this for hours now and I really have no clue...

So any help is really appreciated.

Added information: Both servers use: kernel.printk = 7 4 1 7 (I don't know if that's useful)

Answer 1

Well (thanks to Aaron for pointing me in the right direction) I finally found the little culprit which was causing all the issues I experienced with this script (which worked for every other server, so no need to change that obviously).

The issues were caused by the VERBOSE leven set in vz.conf (located in /etc/vz/ directory). There is an option in there called "VERBOSE" and in my case it was set to 3.

According to OpenVZ's website it does the following:

Increments logging level up from the default. Can be used multiple times. 
Default value is set to the value of VERBOSE parameter in the global
configuration file vz.conf(5), or to 0 if not set by VERBOSE parameter.

After I changed VERBOSE=3 to VERBOSE=0 my script worked fine once again (as it did for every other server). :-)

So a big shoutout to Aaron for pointing me in the right direction. The answer is easy when you know where to look!

^{Sorry to say, but I am kinda disappointed by ndim's reaction. This is the 2nd time he was very unhelpful and rude in his response after that. He clearly didn't read the issue I posted correctly. Oh well.}

Answer 2

I would make sure to properly parse the output of the command. In this case, we are only interested in lines of the form

entered into CT 12345

One way of doing this would be to pipe everything through sed and having sed print only the number when the line looks as above (untested, and I always forget which braces/brackets/parens need a backslash in front of them):

whateverthecommand | sed -n 's/^entered into CT ([0-9]{1,})$/\1/p'