Most powerful examples of Unix commands or scripts

Question

There are many things that all programmers should know, but I am particularly interested in the Unix/Linux commands that we should all know. For accomplishing tasks that we may come up against at some point such as refactoring, reporting, network updates etc.

The reason I am curious is because having previously worked as a software tester at a software company while I am studying my degree, I noticed that all of developers (who were developing Windows software) had 2 computers.

To their left was their Windows XP development machine, and to the right was a Linux box. I think it was Ubuntu. Anyway they told me that they used it because it provided powerful unix operations that Windows couldn't do in their development process.

This makes me curious to know, as a software engineer what do you believe are some of the most powerful scripts/commands/uses that you can perform on a Unix/Linux operating system that every programmer should know for solving real world tasks that may not necessarily relate to writing code?

We all know what sed, awk and grep do. I am interested in some actual Unix/Linux scripting pieces that have solved a difficult problem for you, so that other programmers may benefit. Please provide your story and source.

I am sure there are numerous examples like this that people keep in their 'Scripts' folder.

Update: People seem to be misinterpreting the question. I am not asking for the names of individual unix commands, rather UNIX code snippets that have solved a problem for you.

Best answers from the Community

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Traverse a directory tree and print out paths to any files that match a regular expression:

find . -exec grep -l -e 'myregex' {} \; >> outfile.txt 

Invoke the default editor(Nano/ViM)

(works on most Unix systems including Mac OS X) Default editor is whatever your "EDITOR" environment variable is set to. ie: export EDITOR=/usr/bin/pico which is located at ~/.profile under Mac OS X.

Ctrl+x Ctrl+e

List all running network connections (including which app they belong to)

lsof -i -nP

Clear the Terminal's search history (Another of my favourites)

history -c

Answer 1

• grep
• awk
• sed
• perl
• find

A lot of Unix power comes from its ability to manipulate text files and filter data. Of course, you can get all of these commands for Windows. They are just not native in the OS, like they are in Unix.

and the ability to chain commands together with pipes etc. This can create extremely powerful single lines of commands from simple functions.

Answer 2

My personal favorite is the lsof command.

"lsof" can be used to list opened file descriptors, sockets, and pipes. I find it extremely useful when trying to figure out which processes have used which ports/files on my machine.

Example: List all internet connections without hostname resolution and without port to port name conversion.

lsof -i -nP

http://www.manpagez.com/man/8/lsof/

Answer 3

When solving problems on faulty linux boxes, by far the most common key sequence I type end up typing is alt+sysrq R E I S U B

Answer 4

:() { :|: &} ;: 

Fork Bomb without root access.

Try it on your own risk.

Answer 5

Grep (try Windows Grep)

sed (try Sed for Windows)

In fact, there's a great set of ports of really useful *nix commands available at http://gnuwin32.sourceforge.net/. If you have a *nix background and now use windows, you should probably check them out.

Answer 6

Start all WebService(s)

     find -iname '*weservice*'|xargs -I {} service {} restart

Search a local class in java subdirectory

     find -iname '*.java'|xargs grep 'class Pool'  

Find all items from file recursivly in subdirectories of current path:

     cat searches.txt| xargs -I {} -d, -n 1 grep  -r {} 

P.S searches.txt: first,second,third, ... ,million