nixCraft – Linux and Unix tutorials for new and seasoned sysadmin

How to install xfs and create xfs file system on Debian/Ubuntu Linux

September 23, 2017in Debian / Ubuntu, File system, Linux last updated September 23, 2017

I recently switched to a Ubuntu/Debian Linux server from a CentOS/RHEL 7.x. How do I install mkfs.xfs command on a Debian/Ubuntu Linux server? How do I create and manage file XFS file system on a Ubuntu or Debian Linux LTS server?

userdel: user vivek is currently used by process 749 error and fix on Linux

September 22, 2017in CentOS, Debian / Ubuntu, Linux, Suse, User Management last updated September 22, 2017

I am trying to delete a user named vivek using the userdel command as follows

userdel -r vivek
userdel: user vivek is currently used by process 749

How do I fix this problem and delete username vivek on a Debian Linux 9.x server?

How to find bash shell function source code on Linux/Unix

September 22, 2017September 22, 2017in BASH Shell, Linux, UNIX last updated September 22, 2017

I am a new Linux server user. I cannot figure out how to find out the source code of a bash function named foo() which is defined. How to locate the file where a bash function is defined and how to view the source code of foo() from shell prompt itself?

How to find disk I/O latency with ioping monitoring tool on Linux

September 21, 2017in FreeBSD, Linux, Mac OS X, OpenBSD, UNIX last updated September 21, 2017

How do I monitor disk I/O latency in real time on Linux, FreeBSD, OpenBSD, and MacOS operating system?

How to find and replace text/IP address with Ansible

September 21, 2017in Linux, UNIX last updated September 21, 2017

I need to find an IP address in the sshd_config file and replace with a fresh one for over 100+ VMs. How do I use Ansible to do so? Is it possible to search replace single string or IP address?
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How To Set Up a Firewall with PF on FreeBSD to Protect a Web Server

August 29, 2017August 29, 2017in FreeBSD, OpenBSD, PF Firewall, Security last updated August 29, 2017

I am a new FreeBSD server user and moved from netfilter on Linux. How do I setup a firewall with PF on FreeBSD server to protect a web server with single public IP address and interface?

How to delete files containing a character or number/digit in their filename on Linux or Unix

August 23, 2017August 24, 2017in BASH Shell, Linux, UNIX last updated August 24, 2017

I am a new Linux system user. How do I delete file containing a character ‘a’ or ‘z’ in their filename or digit such as ‘4’ or ‘2’ in their filename on Linux or Unix bash shell prompt?