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I'm wondering about tools that are powerful and that most system administrators either don't know about or don't use (but should).

Thus, things like sudo, vi, emacs, dtrace, ps, and top are out. I have some ideas but I just hate to skew the statistics...

I'll just wait and see if anyone mentions my favorites.

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closed as not a real question by Chris S Feb 26 '12 at 20:07

It's difficult to tell what is being asked here. This question is ambiguous, vague, incomplete, overly broad, or rhetorical and cannot be reasonably answered in its current form. For help clarifying this question so that it can be reopened, visit the help center.If this question can be reworded to fit the rules in the help center, please edit the question.

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There are so many 'what tools' questions, do we really need another? –  Zoredache Jun 6 '09 at 9:49
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I just have to ask: if no one's heard of a tool, then how will it get upvotes? –  quux Jun 7 '09 at 2:52
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Please mention one tool per answer. –  Cristian Ciupitu Aug 4 '09 at 14:18

40 Answers 40

I personally never go anywhere without UnxUtils. It's got a very large amount of Nix command line utilities. Some of my faves include: find, wget, and sed. And of course it's nice to not have to remember to type dir/copy/etc when I'm switching to a Windows machine after a long stint on a nix machine.

Throw in a batch file to quickly add it to your PATH and you're good to go.

http://sourceforge.net/projects/unxutils/

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sdiff. It displays two files in a split screen, showing the direction of change in the middle. It can also merge files interactively.

#sdiff -w 40 /etc/fstab /tmp/fstab
/dev/md0                /dev/md0
/dev/md1                /dev/md1
tmpfs                   tmpfs
devpts                  devpts
sysfs                   sysfs
proc                    proc
LABEL=SWAP-sdb2    |    /dev/sda2
LABEL=SWAP-sda2    <
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PuTTy connection Manager! Tabbed Putty!

http://puttycm.free.fr/

alt text

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dsh

Distributed SHell. With dsh you can perform a command via ssh on multiple servers. I find it quite handy when doing a lot of the same things on a serverfarm, at least when it's not complicated. For instance, doing a reboot of the whole farm is just 'dsh --all reboot'. I wouldn't recommend it for using it interactively. With dsh you can make lists of servers, like a list of all your webservers or all servers located in .uk, and only perform the action on that list.

ClusterSSH

Sort of the same, it spawns multiple ssh sessions and you can input in multiple sessions at the same time. It's extreme usefull when you've got interactive commands, like aptitude dist-upgrade. I found this very usefull when upgrading a serverfarm from etch to lenny.

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tcping

From the author: "tcping.exe is a small (Win32) console application that operates similarly to 'ping', however it works over a tcp port."

It's one of the best (OSI Layer 3+) ways to determine whether a host is powered on and connected to the network.

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HTOP as yet another TOP. For Windows; PortQueryUI as a replacement for NMAP.

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Ncat (part of Nmap 5) is a great replacement for Netcat, OpenSSL's s_client and telnet. I used it recently to test and verify an HTTPS connection over IPv6.

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Windows PowerShell.

Until Windows PowerShell I always was envious about the powerful Linux shells.

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Another set of tools I am surprised isn't used more - or heard of more - is Performance Co-Pilot. This is an amazing performance monitoring tool, and is available on a number of UNIX platforms. It is a distributed performance monitoring tool with historical recording and history recall - and with an amazing set of rules for alarms and so forth.

The rule engine allows you to do things like: notify me if 80% of the disks in the system are busy 90% of the time over the last 5 minutes; notify me if disk space grows at a rate of more than 1Gb/min; notify me if all processors are more than 75% busy during work hours; notify me of swap space used is increasing more than 5% per second for the last minute.

The tool also allows you to run the programs not only in real-time - even against hosts across the network - but also over an archive file acting as if it was in real-time.

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DBAN

Excellent bootable CD (or floppy) for completely wiping the contents of a hard drive. I use it in two ways:

  1. Zeroing out a hard drive before installing or reinstalling an OS.
  2. Securely wiping a hard drive before shelving it or destroying it.

It's great, and it's easy to use. It runs in about an hour on most of the disks I have ever tried it on, it may require more time for terabyte-class drives, I'm not sure.

This is one example of a good tool that performs one function and performs it right.

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