Category: unix

How to see Time-To-Live (TTL) for a DNS record – nixCraft:

Learn how to check DNS TTL records on Linux/Unix/macOS/*BSD/ and Windows with dig and nslookup commands for troubleshooting purposes.

How to test and validate DNSSEC using dig command line – nixCraft:

Want to troubleshoot and validate DNSSEC validation for your domain? Try these dig command examples for Linux/*BSD/macOS and Unix-like systems. 

How to set rsync speed limit from eating all bandwidth with -bwlimit option – nixCraft:

In this tutorial you will learn how to set up bandwidth I/O limit using rsync command on Linux, MacOS, FreeBSD and Unix-like systems.


It is a must-read for all Unix/*BSD/Linux fans. This is the fascinating story of how Unix began & how it took over the world by Brian Kernighan. The author was a member of the original group of Unix developers & many Unix programmes including AWK. You can grab it from Amazon <=

  • Ctrl+r : Backward search 
  • Ctrl+l : clear
  • Ctrl+s : Pause output
  • Ctrl+q : Resume output after Ctrl+s
  • Ctrl+a : move to the beginning of line (BOL)
  • Ctrl+e : move to the end of line (EOL)
  • Ctrl+k : delete all text from the cursor to EOL 
  • Ctrl+_ : undo

Douglas McIlroy is a professor of computer science, mathematician, engineer and famous programmer. He is one of the original Bell Labs Unix pioneers. You can thank him for UNIX pipelines, diff, sort, tr, and many other commands.  McIlroy (left) with Dennis Ritchie.