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UNIX

How to apply patches on OpenBSD system/kernel and packages easily

I am a regular Linux system user. In Linux (especially CentOS), I am used to applying updates a few times a week using yum command, but how do I do that on my OpenBSD severer? How do I apply updates on OpenBSD operating system?
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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 00:50 every day for root user:
       50 0 * * * /etc/cron.d/backups
How do I fix this problem on Linux or Unix-like system?
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How to make disk image with dd on Linux or Unix

How do I create disk image using dd command? How do I perform disk cloning from a live Linux cd for backup or recovery purpose?
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How to configure pfSense as multi wan (DUAL WAN) load balance failover router

How do I setup a multi-WAN load balancing and failover on pfSense router with two ADSL or cable or leased-line or FTTH (Fiber to the home) connections?
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PHP-fpm Too Many Open Files 24 Error (set open file descriptor limit)

I am getting the following error in my /var/log/php7.0-fpm.log file:
        “ERROR: failed to prepare the stderr pipe: Too many open files (24)
How do I fix this problem?
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How to install htop on pfSense firewall

I am using pfSense version 2.3.2-RELEASE (FreeBSD 10.3-RELEASE-p5). How do I install htop version 2.x on a pfSense firewall?
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How to fix Httpoxy a CGI PHP/Nginx/Apache/Go application vulnerability on Linux or Unix

A serious vulnerability was discovered in how CGI scripts are used by Linux or Unix that use PHP, Go, Python, and other scripting languages. How do I fix Httpoxy a CGI application vulnerability on Linux or Unix for HAProxy, Varnish, Nginx, PHP, Go, Python, Tomcat and others?
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How to get Ethernet Link Speed in MAC OS X Through Command Prompt

I‘m a Mac OS X user. How do I find out my Ethernet Link Speed in terminal using bash shell prompt? How do I see my current Ethernet connection Speed in Mac OS X?
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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 my log file and renaming it my-app.log.gz. How do I force the gzip command to keep original file while maintaining the original file on Linux or Unix-like system?
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Unix / Linux: Remove duplicate lines from a text file using awk or perl

I have a text file with exact duplicates of lines. I need to remove all those duplicates lines and preserves the order too on Linux or Unix-like system. How do I delete duplicate lines from a text file?
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