Centos

Tonight I started to review the learning material for Red Hat System Administration III to prepare for RHCSE exam. I need a machine with GUI, and all my CentOS 7 VMs are headless. So let’s install the GUI on it, shall I? First install epel repo, if it’s not yet installed: # yum install epel-release -y Then install the 2 groups: # yum groupinstall "X Window system" -y # yum groupinstall "MATE Desktop" -y Tip, if “I” can’t remember the names of the groups, I can run this command to list all available groups: ...

I have a server running CentOS 6 successfully upgraded to CentOS 7. The only problem I encountered so far is that ‘grep’ doesn’t work. [root@zilla ~]# grep grep: error while loading shared libraries: libpcre.so.0: cannot open shared object file: No such file or directory [root@zilla ~]# ldd /usr/bin/grep linux-vdso.so.1 => (0x00007ffc0b639000) libpcre.so.0 => not found libc.so.6 => /lib64/libc.so.6 (0x00007f6be1c6c000) /lib64/ld-linux-x86-64.so.2 (0x00007f6be2038000) First thing I tried was to reinstall pcre package which provides libpcre.so*. It still didn’t work. Fortunately, someone has posted a solution as the following: ...

Someone asked this question in one of his blog posts: Ever see this? dhcpd: uid lease 192.168.1.150 for client xx:xx:xx:xx:xx:xx is duplicate on 192.168.1/24 Yes, I’m seeing something like that now in the my dhdcp logs. Here is the actual message: DHCPREQUEST for 192.168.1.109 from 08:00:27:6e:61:b8 via eth0 DHCPACK on 192.168.1.109 to 08:00:27:6e:61:b8 via eth0 DHCPINFORM from 192.168.1.109 via eth0 DHCPACK to 192.168.1.109 (08:00:27:6e:61:b8) via eth0 uid lease 192.168.1.224 for client 08:00:27:6e:61:b8 is duplicate on 192.168.1.0/24 DHCPREQUEST for 192.168.1.109 from 08:00:27:6e:61:b8 via eth0 DHCPACK on 192.168.1.109 to 08:00:27:6e:61:b8 via eth0 I think I know why this happened. Basically, the machine with MAC address of ’08:00:27:6e:61:b8′ used to have grab an IP address ...

This post is primarily written to remind myself, an Ubuntu user, to figure out how to find what RPM package provides a file — for example a header file. Today, I’m trying to compile and install R 3.1.3 on CentOS 6 from source code. This R installation is one of the requirements to install Tessera stack. The instruction from the installation page is: sudo yum install blas blas-devel lapack lapack-devel wget http://cran.r-project.org/src/base/R-3/R-3.1.3.tar.gz tar zxvf R-3.1.3.tar.gz cd R-3.1.3 ./configure --with-blas --with-lapack --with-x --enable-R-shlib make sudo make install Unfortunately, the process failed with ./configure with the complain about missing readline library. To fix it, I had to install readline-devel package. ...

I have been having issues getting X2Go running on a CentOS 6.5 box. It took me a while to figure out that the problem laid with the permission of /tmp directory. I’ll write how to solve the X2Go problem in another post. The recommended permission for /tmp is 1777. Notice that the forwarding ‘1’ is the sticky bit which only allows the owner of the file within /tmp (or the root user) to delete/rename the file. ...