UNIX related tutorial/FAQ

How to override content type with Nginx web server

last updated January 21, 2019 in CentOS, Debian / Ubuntu, FreeBSD, Linux, Nginx, RedHat and Friends, Suse, UNIX

I configured Nginx server. However, it is sending the wrong content type. I need to force Nginx to send specific “Content-Type: text/xml; charset=UTF-8“. How do I configure Nginx to override content type for given URL location?

OpenBSD install MariaDB database server

last updated January 17, 2019 in MySQL, OpenBSD, UNIX

How do I install MariaDB database servers on OpenBSD Unix operating systems?

Bash shell find out if a variable has NULL value OR not

last updated December 27, 2018 in BASH Shell, FreeBSD, Korn Shell Scripting, KSH Shell, Linux, UNIX

I am a new to shell scripting. How do I check for NULL value in a Linux or Unix shell scripts?

How to change root password on macOS Unix using terminal

last updated December 20, 2018 in Mac OS X, UNIX, User Management

I am a new user of macOS Unix running on MacBook Pro and Mac mini server. I need to change the password for root user account on macOS. How do I change the root password on macOS Unix using command line options?

FreeBSD wget cannot verify certificate, issued by Let’s Encrypt

last updated December 17, 2018 in FreeBSD, FreeBSD Jails (VPS), Troubleshooting, UNIX

I installed GNU wget utility on FreeBSD as explained here. However, whenever I use the wget command to download stuff from the Internet, it says:
ERROR: cannot verify download.freebsd.org’s certificate, issued by ‘CN=Let\’s Encrypt Authority X3,O=Let\’s Encrypt,C=US’:
Unable to locally verify the issuer’s authority.
How do I fix this problem on FreeBSD 12?

Bash check if string starts with character such as #

last updated December 14, 2018 in BASH Shell, Linux, UNIX

My bash shell script read a config file line-by-line using a bash while loop. I need to check if a string stored in $var starts with some value such as # character. If so I need to ignore that value and read the next line from my config file. How do I check if variable begins with # in bash shell scripting running on a Linux or Unix-like operating systems?

Bash get exit code of command on a Linux / Unix

last updated December 4, 2018 in BASH Shell, Linux, UNIX

I am a new Linux system user. How do I get the exit code of a command? How do I get the exit code of Linux or Unix shell command and store it into a shell variable?

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