Linux Check Disk Space Command

I recently switched from a Windows server to a Linux server operating system. I am using Ubuntu LTS server. How do I find out disk space utilization information using command line option?   Linux offer…

How To Patch and Protect Linux Glibc Getaddrinfo Stack-based Buffer Overflow Zero Day Vulnerability CVE-2015-7547 and CVE-2015-5229 [ 16/Feb/2016 ]

A stack-based critical buffer overflow was found in the way the libresolv library (glibc) performed dual A/AAAA DNS queries. A remote attacker could crash or, potentially, execute code running the library on Linux. How do…

How to copy permissions from one file to another on Linux

I need to copy or clone file ownership and permissions from another file on Linux. Is there a bash command line option to clone the user, group ownership and permissions on a file from another…

How to gzip and keep original file on Unix or Linux command line

I would like to compress a log file using gzip Unix command line utility, and I would also like to keep the original file. However, when I use the gzip my-app.log command, results in modifying…

How to gzip and keep original file on Unix or Linux command line

I would like to compress a log file using gzip Unix command line utility, and I would also like to keep the original file. However, when I use the gzip my-app.log command, results in modifying…

Linux Iptables Delete postrouting Rule Command

I am a new Linux server sysadmin. I need to delete POSTROUTING rule. How do I delete postrouting rule on Linux server?   You need to use iptables and ip6tables command. These commands are used…

How to determine Linux guest VM virtualization technology

I have a cloud-based virtual machine running Ubuntu and CentOS Linux server. It may or may not be virtualized. How do I determine what kind of virtualization technology (VMWARE/ KVM/ XEN/ VirtualBox/ Container/ lxc/Hyper-V etc.)…

Linux how long a process has been running?

I‘m a new Linux system user. How do I check how long a process or pid has been running on my Ubuntu Linux server?   You need to use the ps command to see information…

How to make disk image with dd on Linux or Unix

H ow do I create disk image using dd command? How do I perform disk cloning from a live Linux cd for backup or recovery purpose?   You can easily use the dd command for…

cron Error: bad username; while reading /etc/cron.d file on Linux

I am getting the following error in my cron job log file /var/log/cron.log: Aug 22 01:59:01 server2 cron[7510]: Error: bad username; while reading /etc/cron.d/backups I have job entry as follows to run a job at…