Tools a Unix administrator cannot live without

Question

After administering Unix or Unix-like servers, what tools (command-line preferably) do you feel you cannot live without?

score 51 · Answer 1 · answered May 03 '09 at 08:36

51

GNU screen - essential when you're managing large numbers of systems and don't want to have a dozen terminal windows open.

answered May 03 '09 at 08:36

Murali Suriar

10,406

score 34 · Answer 2 · edited Apr 05 '10 at 09:33

Some I know that I cannot live without...

tee - allows simultaneous writing to STDOUT (standard output) and a file. Great for viewing information and logging it for later.
top - the task manager of UNIX, gives a great overview of the system.
tail -f - allows you to view appended data as a file grows, great for monitoring log files on a server.
grep - Global Regular Expression Print, great for searching the system for data in files.
df - reports disk usage of current filesystems.
du - reports disk usage of a certain file/directory.
less - needed to view man pages! also useful for viewing output of commands in an easily seekable manner.
vim/Emacs/nano/pico/ed - whatever your text editor of choice may be, self explanatory of why it's needed.

erichui · Answer 3 · 2009-05-04T01:07:35.370

26

lsof to determine which processes are using a file or directory (useful when trying to figure out what is preventing a device from being umount'd)

netstat to determine which processes are using network connections (especially useful when trying to figure out which daemon is bound to a certain port)

edited May 04 '09 at 01:07

answered May 04 '09 at 00:26

erichui

270

score 19 · Answer 4 · answered May 04 '09 at 06:05

Learn all the basic tools, but learn Perl.

Perl is ideal for manipulating text, and since un*x operators live on text files, pipes, input and output, Perl is a great fit.

The added bonus is Perl is cross platform and if you have to do some work on a windows box you have an easily installable (just drop a Perl directory on the server) language that you already know.

And on that train of thought, get Cygwin as well. If you are a un*x admin and have to work on a windows box (even your desktop) having ls, rm, grep, sed, tail etc save you a lot of time when switching OS's.

score 18 · Answer 5 · answered May 04 '09 at 06:30

sed
awk

The forgotten grandfathers of modern systems scripting. I know Perl gets most of the love (along with Bash scripting, Python, Ruby, and [insert your favorite scripting language here]), and don't get me wrong, I love Perl. I make use of it almost daily.

But sed and awk should not be forgotten, overlooked, or ignored. For a lot of cases, sed and awk are the best tools for the job. Quick examples are command line filtering with sed, and quick and dirty log processing with awk. Both could be done in Perl, but will require more work and development time.

score 13 · Answer 6 · edited Jul 22 '12 at 22:36

13

rsync, especially in concert with ssh. It allows simple efficient copying of files from host to host. How did we ever cope without ssh and rsync? :-)

edited Jul 22 '12 at 22:36

pQd

30,537

answered Jun 01 '09 at 14:24

dr-jan

432

score 12 · Answer 7 · edited Feb 26 '12 at 12:14

12

Face it - sooner or later you'll deal with the network as well. mtr, tcpdump and tshark are really useful for seeing what's happening.

edited Feb 26 '12 at 12:14

Peter Mortensen

2,327

answered May 24 '09 at 10:22

pQd

30,537

score 12 · Answer 8 · answered Jun 01 '09 at 14:32

12

Netcat.

Test if TCP services are listening.
Perform transactions against plaintext protocols such as SMTP.
Quick insecure data transfers between machines.
Telnet client emulation.

The network swiss army knife, as they say.

answered Jun 01 '09 at 14:32

Dan Carley

26,127

score 9 · Answer 9 · answered Jun 04 '09 at 20:31

9

I use most of the tools already listed, but here's one no one has touched on yet:

Puppet - system for automating system administration tasks

answered Jun 04 '09 at 20:31

Shaun Hess

504

score 9 · Answer 10 · answered May 03 '09 at 07:30

9

For quick scripts, automation, etc:

bash
perl

To connect to your *NIX server:

Open SSH (Linux client)
Putty (Windows client)

answered May 03 '09 at 07:30

Paul

133

score 6 · Answer 11 · answered Jun 01 '09 at 16:05

A couple of handy tools I haven't seen mentioned yet:

dstat --nocolor (overview of cpu-, disk-, net-usage)
iftop (nice dynamic overview of network traffic)
ccze (colour logfiles nicely)
ssh tunnels (can be useful once in a while; see the manual; -R)
expect (automate interactive, chatty dialogy interfaces, nice if you're in a pinch)

score 6 · Answer 12 · answered May 03 '09 at 10:56

6

For scripting:

python
gawk

answered May 03 '09 at 10:56

Pablo Santa Cruz

1,164

score 6 · Answer 13 · answered May 05 '09 at 10:37

6

Most of the standard ones are included in other answers, so I'll go fo non-standard ones:

htop — great for process management;
pinfo — lynx like browser for info and man pages.

answered May 05 '09 at 10:37

vartec

6,277

score 5 · Answer 14 · answered May 05 '09 at 10:56

5

ClusterSSH

ClusterSSH controls a number of xterm windows via a single graphical console window to allow commands to be interactively run on multiple servers over an ssh connection.

answered May 05 '09 at 10:56

Tom Feiner

18,598

score 4 · Answer 15 · edited Feb 26 '12 at 17:20

4

ssh, Vim, htop, su, Python, ls, cd, screen, du, tar :)

edited Feb 26 '12 at 17:20

Peter Mortensen

2,327

answered Jun 02 '09 at 20:41

score 4 · Answer 16 · answered Jun 04 '09 at 22:57

pv: Displays the progress of long operations that can be redirected. http://www.ivarch.com/programs/pv.shtml

Useful then you want to monitor something that is going to take ages, like copying/compressing a raw block device over the network (which is how I take paranoia backups of my 8Gb netbook before tinkering with anything major like tweaking with file system settings).

Also: I'll second votes for ssh, rsync, screen, htop and netcat as mentioned by people above - all of which are more important than pv but pv had not been mentioned yet. In fact pv is often a useful addition when piping stuff to or from to netcat.

score 4 · Answer 17 · answered May 05 '09 at 00:48

4

vmstat 1

Gives you a great overview of system behaviour.

answered May 05 '09 at 00:48

score 3 · Answer 18 · edited Feb 26 '12 at 12:17

Most of these tools are made much more powerful using Bash "programmable completion" - so you can tab-complete things like commandline options, or say the name of a package with "apt-get install". It will also limit what you tab-complete for relevant files - for example, "unzip" will only complete supported archive files.

It really is the mutts - if you have never tried it you probably just need to fiddle your .bashrc:

if [ -f /etc/bash_completion ]; then
    . /etc/bash_completion
 fi

Certainly this is true on Ubuntu and Debian. You may need to get the package on some Linux distributions.

score 3 · Answer 19 · answered Jun 02 '09 at 01:43

tar pipe!

piping the output of tar to another utility, to tar running on the same box, or to tar running over SSH is my favorite old-school Unix move for moving files from one place to another.

This also gives you the Windows-style option of copying one folder to another and ending up with all of the files in the source and destination directory.

score 3 · Answer 20 · answered Jun 04 '09 at 22:46

3

zsh as a shell

It is especially efficient with grml.org's extensions/setup.

answered Jun 04 '09 at 22:46

cstamas

6,917

score 3 · Answer 21 · answered May 03 '09 at 07:15

3

sudo.

Seriously though, tail -f is useful.

answered May 03 '09 at 07:15

Sophie Alpert

1,629

score 3 · Answer 22 · answered Jul 15 '09 at 19:58

3

iotop, is a top-like program to monitor I/O accesses to your disks.

answered Jul 15 '09 at 19:58

Emilio

55

score 3 · Answer 23 · answered May 05 '09 at 12:13

3

Some that haven't been mentioned before:

head/tail
diff
pstree
tar
gzip/bzip
watch

answered May 05 '09 at 12:13

CK.

1,173

score 2 · Answer 24 · answered Jun 01 '09 at 16:44

A few things overlooked I wanted to mention.

vim -d split screen console diff that makes it very easy to see the differences in a file
pdsh allows you to easily run a command over as many systems as you want either serial or parallel(I am a cluster admin. I can't function without it.)
nmon is like top on crack. It gives you a great idea of what is going on on a system on a single screen. You can see disk I/O, network I/O CPU usage, and memory usage real time. At the very least a real fun thing to play with when profiling a system.

Oh, and I forgot to mention, when scripting, I believe you should always use Korn. I hate Korn(Not the band. I love the band:-P) but it's literally everywhere. You can take a script and move it between Solaris, AIX and Linux and not have to worry about whether or not the admin had the decency to install Bash.

score 2 · Answer 25 · edited Feb 26 '12 at 18:20

2

The shutdown command.

edited Feb 26 '12 at 18:20

Peter Mortensen

2,327

answered Nov 23 '10 at 14:16

user237419

1,653

score 2 · Answer 26 · answered Jun 05 '09 at 15:27

2

One tool sometimes very handy is nohup. I use it to run scripts that last for a long time using remote SSH clients.

answered Jun 05 '09 at 15:27

score 2 · Answer 27 · edited Apr 12 '10 at 08:49

2

I love AWK as well as "for" on the command line.

Especially to build up a list of commands I want to run and then execute them all at once.

edited Apr 12 '10 at 08:49

Peter Mortensen

2,327

answered Jun 26 '09 at 14:53

Brian G

375

score 2 · Answer 28 · edited Apr 12 '10 at 08:48

2

vi

find

ssh

AWK

sed

netcat

tar

ps

edited Apr 12 '10 at 08:48

Peter Mortensen

2,327

answered Jun 26 '09 at 14:58

Maxwell

5,086

score 2 · Answer 29 · answered Jun 26 '09 at 15:02

2

man - to read the man pages.

elinks - to check google, cause I sure as hell cant remember everything.

And attention to detail & tenacity, because without them I just waste time.

answered Jun 26 '09 at 15:02

pjd

131

score 2 · Answer 30 · answered Jul 15 '09 at 20:16

2

screen is a must, especially with a good .screenrc file. I have it configured to display visually which window I'm in and can move between them with Ctrl+Arrow. For a single ssh session and multiple shells, it is a life saver.

answered Jul 15 '09 at 20:16

Nasko

727

score 2 · Answer 31 · edited Apr 13 '17 at 12:14

2

Some additional answers can be found in this similar question

edited Apr 13 '17 at 12:14

Community

1

answered May 05 '09 at 12:19

Vagnerr

1,275

score 1 · Answer 32 · edited Apr 12 '10 at 08:47

1

Bash
Vim
iostat
ps
top
lsof
strace
tcpdump
netstat
find
grep
Perl
sed
tail
dig
traceroute

Where possible the GNU versions of the above over the propritary versions.

edited Apr 12 '10 at 08:47

Peter Mortensen

2,327

answered Apr 05 '10 at 14:12

Jason Tan

2,792

score 1 · Answer 33 · edited Apr 12 '10 at 08:52

1

rsync running over ssh to keep things consistent... in multiple directions (-gloptru[n]c)
Vim and vimdiff to edit with 'folding' and viewing differences in scripts, logs, etc.
Perl and (Ba)sh for scripting and analysis
cURL (and maybe Wget) for posting/fetching data from ...
Apache to webify them all (or at least create point-n-click admin tools)

edited Apr 12 '10 at 08:52

Peter Mortensen

2,327

answered Jun 04 '09 at 19:43

ericslaw

1,592

score 1 · Answer 34 · edited Apr 12 '10 at 08:51

1

Perl and Vim. In that order. Anything else, I can use Perl to emulate somehow.

edited Apr 12 '10 at 08:51

Peter Mortensen

2,327

answered Jun 04 '09 at 20:45

Alexandre Carmel-Veilleux

509

score 1 · Answer 35 · edited Apr 12 '10 at 08:50

All the standard commands and utilities (Bash, grep, sed, AWK, find, xargs, ssh, Vim, etc.)

Lsof, awesome in so many ways, I love to use it for finding open ports AND the files associated with that process.
Screen, for multi-session awesome.
Tcpdump, its funny how many application problems are really weird network issues
Ruby, makes more sense to me than Perl, becoming wildly popular for SA work.
Chef, configuration management system.
Capistrano, ssh in a for loop, but less crappy. And in Ruby.
Rake, more sensible than make.

score 1 · Answer 36 · edited Apr 12 '10 at 08:49

1

These are the tools I use on a daily basis (as a developer more than a system administrator)

zsh
lsof
ps
ack (or grep)
find
svn
Python
tar
which
fortune (a guy has to keep his sanity somehow)

edited Apr 12 '10 at 08:49

Peter Mortensen

2,327

answered Jun 05 '09 at 15:44

score 1 · Answer 37 · answered May 03 '09 at 07:38

1

Simple, basic but still essential:

ps - report a snapshot of the current processes.

free - Display amount of free and used memory in the system.

w - Show who is logged on and what they are doing.

answered May 03 '09 at 07:38

gimel

1,203

Iain Holder · Answer 38 · 2009-05-04T11:13:36.443

1

pkill or ps for killing processes.

If you want to use ps to kill any process with a given name or under a certain directory blah (or any matching string you require) you can:

kill `ps -ef | grep <blah> | grep -v grep | awk '{print $2}'`

edited May 04 '09 at 11:13

answered May 03 '09 at 11:39

Iain Holder

240

score 1 · Answer 39 · answered Feb 26 '12 at 12:51

nmon

Haven't seen anyone mention this yet.

The nmon tool is designed for AIX and Linux performance specialists to use for monitoring and analyzing performance data, including:

CPU utilization
Memory use
Kernel statistics and run queue information
Disks I/O rates, transfers, and read/write ratios
Free space on file systems
Disk adapters
Network I/O rates, transfers, and read/write ratios
Paging space and paging rates
CPU and AIX specification
Top processors
and more

Can be run in file mode which generates a big CSV file. IBM also provide an Excel macro for parsing this and turning it in to awesome graphs, although you do need a Windows VM for that.

nagios and munin for monitoring and graphing.

score 0 · Answer 40 · answered Jun 04 '09 at 20:09

atop - yet another top alternative, great for monitoring changes in processes
strace/ltrace - for tracking down those REALLY annoying bugs
ldd - track down broken library dependencies
cron, logrotate ;)

Of course, beyond command line, you need Nagios/Cacti/MRTG/etc...

score 0 · Answer 41 · edited Apr 12 '10 at 08:51

0

Learn Vim or Emacs in and out!!
For text editing
Grep
Sed
AWK

For network tools
Nmap
dig

edited Apr 12 '10 at 08:51

Peter Mortensen

2,327

answered Jun 04 '09 at 20:36

XTZ

183

score 0 · Answer 42 · answered Nov 23 '10 at 13:58

0

munin is a great tool for doing capacity analysis and review, but you need to set it up before you need it. We install it as a standard part of every server install we do.

answered Nov 23 '10 at 13:58

Sean Reifschneider

10,990

Tools a Unix administrator cannot live without

42 Answers42

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