_X11TransSocketINETConnect() can't get address for localhost

I connected a CentOS 5 box using PuTTY and ran emacs, but I got the following error.

------------------------------------------------------
$ emacs
_X11TransSocketINETConnect() can't get address for localhost:6011: Name or service not known
emacs: Cannot connect to X server localhost:11.0.
Check the DISPLAY environment variable or use `-d'.
Also use the `xhost' program to verify that it is set to permit
connections from your machine.
---------------------------------------------------

I use Xming as an X server on Windows XP. I checked the X11 option of PuTTY, the sshd setting, and the firewall setting. All the settings were okay. According to the error message, the problem is that the name of "localhost" is not resolved. I took a look at the /etc/hosts file and found the file was empty. So I added the following line to the file.

127.0.0.1 localhost.localdomain localhost

The problem is fixed. I don't know why the file is empty though...

CentOS 5.1 Released

CentOS 5.1 has released. Updating from 5.0 is really easy. Just run

# yum update

I updated my linux box running CentOS 5.0 to 5.1 using yum without any errors. The changes from 5.0 are found in Release Notes.

Many thanks to the CentOS developers!

Package Management on RHEL4 and RHEL5

Here is the difference of the package management commands on between RHEL4 and RHEL5. Of course, you can use the rpm command for both versions, but the frond-end tool for the package management is different. It is good to know the difference.

• Add or Remove package (GUI)

- RHEL5
# pirut

- RHEL4
# system-config-packages

• Update package (GUI)

- RHEL5
# pup

- RHEL4
# up2date

• Add, Remove or Update package (CLI)

- RHEL5
# yum

- RHEL4
# up2date-nox