LAMPdocs: Linux, Apache, MySQL, PHP

Today I’ve noticed a strange thing after Directadmin software update. Exim stopped processing e-mails, the thing that is really necessary for any server. I’ve started to look through log files to identify the problem. Here is what I have at the moment.

My mainlog (/var/log/exim/mainlog) is full of messages like this:

2008-10-30 19:27:02 exim 4.67 daemon started: pid=16453, -q15m, listening for SMTP on port 25 (IPv4) port 587 (IPv4)
2008-10-30 19:27:03 1KvZad-0001Ra-TE unable to set gid=12 or uid=510 (euid=8): domain_filter router (recipient is luna@mydomain.com)
2008-10-30 19:27:03 1KvZad-0001Ra-TE internal problem in domain_filter router (recipient is luna@mydomain.com): failure to transfer data from subprocess: status=0100 readerror=’Success’

Messages are not delivered and I’m trying to investigate the issue. paniclog has messages similar to the shown above.

What are the ideas? First of all I’ve checked all the file permissions and they were ok. I’ve compared them to the permissions of a working server and found no difference. Then I’ve checked domain_filter setting of exim.conf: everything seems to be good too.

The idea came fromone of the numerous mailing lists. And it was simple enough to solve my issue. I just had to add a sticky bit to exim executable with one command. Here is what I had before:

The command I had to enter was chmod u+s exim

This solved all the issues after exim reboot. The most strange thing is that at another server such a software update came without anything like this: all the permissions were OK. Just preventing you from spending so much time: if you’re getting a problem like this, most probably you will be able to solve it with one single command.

Just found some on the internet. I can’t find any proof of this information, but I think the data is quite real. So, I will show you keywords with top cpc, and top google cost per month.

Google.Adsense TOP by Google Cost

Google Adsense TOP 2008 by CPC

This information was copypasted from here. Let me repeat that I don’t know anything about the source of this info. But… I hope it will be useful for you

Sometimes you need to truncate a file to zero bytes. For example you have a big file that contains various logs and its size is too big to open it easily. Of course, you can revome this file and touch it again. But this way you’ll have to deal with permissions and file ownership. There is a simple command that will truncate the file to zero length without affecting any permissions. Here it is:

:>filename

If the file already exists, it will be truncated to zero bytes, else this command will create an empty file. This is great for truncating big log files, e,g. Apache logs.

Today I come with a short and simple command that will be useful for Linux newbies. What to do if you need to find out whether the package you need is already installed or not? There is a short command that will allow you to do this.

rpm -qa | grep <package>

What does this do? This command queries all installed rpms and sends them to grep that is able to tell us whether it is the package we need. For example, if we need to know whether httpd is installed (I mean rpm installations only, compiling apache from source has nothing to do with rpm), we need to enter this command:

rpm -qa | grep httpd

I think this command will be useful for you: you will always know what software you have installed on your server. If you need to list all the packages that are installed, you’re welcome to type:

rpm -qa

This command will list all the packages you have.