Datacenter Oliekoets

Just a quick update, to let you all knowing that the private datacenter is now redundant IaaS. The only thing it does not offer (yet) is a redundant network. The main cluster filesystem is spread over 4 hosts on 2 locations, which should improve reliability. Its also reliable to assume, that when you mirror hardware… Continue reading Datacenter Oliekoets

Saturdaynight Ubuntu puzzle

For the Unix saturday night puzzle entry: #!/bin/bash cat $1|while read EMPID FIRST INIT LAST JOB SEX DATEX SAL EXT1 EXT2 do if [[ ${SAL} == “” && FIRST != “” ]]; then SAL=${DATEX} DATEX=${SEX} SEX=${JOB} JOB=${LAST} LAST=${INIT} INIT=””; fi let DATEPOCH=`date -d “$DATEX” +%s 2>/dev/null` 2>/dev/null let DATEPOCH=${DATEPOCH}-1 DATEX=`date –date @${DATEPOCH} +”%Y-%m-%d”` if [[… Continue reading Saturdaynight Ubuntu puzzle

Counting Inode usage on a directory

See the script below. Really useful if you are running out of inodes. #!/bin/bash # count inodes for each directory LIST=`ls` for i in $LIST; do echo $i find $i -printf “%in” | sort -u | wc -l done

Deleting lost+found is a bad idea

I recently came across an oracle redhat linux server without lost+found. It had been deleted because oracle needs an empty directory on installation. Albeit this is an insane rule, deleting an important system directory is a really bad idea. I will tell you why.

Detect VMware guest in cfengine

There are a few reliable ways to detect if the host is a VMWare guest. The ones below make the most sense. First choice: “vmware_guest” expression => returnszero(“/bin/grep -qi vmware /proc/scsi/scsi”,”noshell”); Second choice: “vmware_guest” expression => fileexists(“/usr/sbin/vmware-toolbox-cmd”);

Evaluation order of $PATH variable and why its important to understand.

I recently came across a default SLES installation which has the following $PATH: (truncated for clarity) /sbin:/usr/sbin/:${HOME}/bin:/bin:/usr/sbin/:/usr/local/bin ………. This at first glance appears as a security problem , as a malevolant user can add $HOME/bin/ls and a user can execute a different ls or other arbitrary command that does something totally different. However, changing the… Continue reading Evaluation order of $PATH variable and why its important to understand.

Owncloud

I installed owncloud today on my private unix webserver. Installation was fast & painless with Mysql backend, but sqlite somehow didn’t work. This program really is an awesome web application, as it allows you many things. It even intergrates my roundcube webmail client painlessly. -Mark.