UNIX related tutorial/FAQ

Change default shell to bash on Macos Catalina

last updated October 8, 2019 in BASH Shell, Mac OS X, UNIX

I noticed that my default shell set to zsh on Macos Catalina. How do I change my default shell to bash on Macos Catalina using the command line or GUI options?

Linux run a command with a time limit (timeout)

last updated September 26, 2019 in BASH Shell, CentOS, Debian / Ubuntu, Linux, Programming, RedHat and Friends, Suse, UNIX

I want to start command called foo, and kill it if still running after given DURATION in seconds. How do I run a command a time Limit on Linux? How do I run a Linux command, and have it timeout (abort) after N seconds?

How to add users on FreeBSD using adduser or pw

last updated September 22, 2019 in FreeBSD, FreeBSD Jails (VPS), UNIX, User Management

I am a new FreeBSD system administrator. How do I add users on FreeBSD Unix operating systems using command line?

How to install htop on FreeBSD

last updated September 14, 2019 in FreeBSD, FreeBSD Jails (VPS), Package Management, UNIX

I am a new user of FreeBSD operating system. How do I install htop on FreeBSD using the pkg command?

FreeBSD Applying Security Updates Using pkg/freebsd-update

last updated September 12, 2019 in FreeBSD, FreeBSD Jails (VPS), Package Management, UNIX

I am a new FreeBSD developer and user. I have root access to my VM running in AWS cloud. How do I update packages and apply security upgrades on FreeBSD? What is the procedure for applying security updates on FreeBSD?

How to check disk space on Unix servers

last updated July 26, 2019 in AIX, Commands, FreeBSD, HP-UX Unix, OpenBSD, UNIX

I recently switched from a Windows server 2016 to a FreeBSD Unix server. I need to check disk space on Unix command line. How do I find out disk space utilization information using the Unix command-line option?

Check if a directory exists in Linux or Unix shell

last updated May 21, 2019 in BASH Shell, KSH Shell, Linux, UNIX

I need to check if a directory exists or not, within a shell script running on Linux or Unix-like system? How do I check if a directory exists in a shell script?

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