Lazy Linux: essential tricks for admins

http://www.ibm.com/developerworks/linux/library/l-10sysadtips/?S_TACT=105AGX54&S_CMP=C0115&ca=dnw-1002&open&cm_mmc=4633-_-n-_-vrm_newsletter-_-10731_101108&cmibm_em=dm:0:6992641

by jaspertheghost • 18 years ago

162 53 18 years ago

ibm.com

mlLK3• 18 years ago

While how-to lists hardly see the light of day (the front page) on HN, I had hate to see one like this go unrecognized.

mark_h2• 18 years ago

Agreed; way better than the usual lists.

babo• 18 years ago

A pretty unique collection, worth a look!

lallysingh• 18 years ago

Quick question, is it just me or is gig ethernet 1000 Mbps, not 1024?

Man "mebibits" sounds terrible.

iigs• 18 years ago

Trick 5 (opening a remote port on a "public" machine to connect back to your local machine) is great. Combine it:

office$ ssh -R 9999:localhost:22 user@home ## do this in a screen for good measure

and another lesser known ssh feature:

home$ ssh -D 8888 -p 9999 user@localhost

and now you have a SOCKS proxy on home:8888 that will access everything visible to the computer named "office".

For extra credit add PingTunnel and a hotspot that happens to allow ICMP and enjoy free internet wherever you go.

gommm• 18 years ago

Thanks for the tip on ping tunnel, I hadn't heard of it.... Going to have fun checking it out

mark_h2• 18 years ago

Yeah, that was exactly the one that stood out for me! I've wanted this several times recently, at work and at play.

sven• 18 years ago

combine your ssh-tunnel-socks-proxy with tsocks, and you have a nearly transparent access for your applications on your home-box into the office.

raamdev• 18 years ago

Very nice collection. A tech at the datacenter that hosts one my servers showed me trick #3 and I remember being thrilled sitting there watching him do stuff on my server and sharing the keyboard to type messages back and forth in vi.

My company uses trick #5 as a primary feature for accessing the remote Linux machines that our product is built upon. We have it set up so that every single machine automatically creates a reverse SSH tunnel to the server on boot, so that the tunnel is always accessible in case we need it. Very cool stuff.

Goladus• 18 years ago

If you thought #8 was really cool and useful, you should go learn bash, sed, and awk. Stuff like #8 is what makes unix fun.

LogicHoleFlaw• 18 years ago

When I was doing AIX administration, I liked that one command to kill processes with open files keeping a mountpoint mounted was:

  fuser -fuck /dev/whatever

http://moka.ccr.jussieu.fr/doc_link/C/a_doc_lib/cmds/aixcmds...

Oh, admin humor.

mlLK3• 18 years ago

Any admins care to share some pornographic passwords?

     p4ss1ng g4s 1n h3r 4ss w/ my sp34r
     d4n4 d03s d1ld0s @t d4 d1ld0 st0re
     d1ck r4p3d j4n3 w/ h1s d1ng d4ng

mlLK3• 18 years ago

Are you're kidding me? If I must really share. . .most sys admins encourage their users to come up with passwords that read like 'pornographic catch phrases' written in 1337 speak as means of ensuring system security while the end-user is less likely to forget their password since it's something offensive yet expressive.

yters• 18 years ago

People are hitting the downvote button more.

ionfish2• 18 years ago

My general attitude to passwords is "Never choose something you'd be ashamed to recite to your mother over the phone", since you never know when you'll be in a position where you may have to do exactly that.

khafra2• 18 years ago

As an information assurance guy, I'd encourage users to use the most embarassing possible passwords, since you should never share them. If you need to make resources available to more entities, do it by sharing access, not authentication.

meep• 18 years ago

Is it just me or are downvoted posts completely unreadable? It would be nice if there were an "unhide" button or something; it's extremely annoying to have to squint to read it.

pg• 18 years ago

That's intentional. Downvoted posts fade both to save people from reading them (presumably most are mistaken or nasty) and to damp the submitter's karma loss (the fainter they are, the harder you have to work to be offended by them).

sunkencity• 18 years ago

great list! I especially liked the tip about sharing a screen session, been wanting a solution like that many times!

another great tip is how to list all subdomains on registered (not all dns servers allow this, many times you need to be on the same network, or it isn's allowed at all, but for solving you own dns issues it's a boon)

dig mydomain.com. axfr

delano4• 18 years ago

A better title: 9 interesting Linux commands and 1 reason to absolutely avoid CentOS.

jrp• 18 years ago

You mean booting to singleuser? If you don't want it just use a grub password; nothing to do with CentOS.

delano4• 18 years ago

Is the procedure for changing the root password with grub the same regardless of the flavour of Linux?

davidw3• 18 years ago

What are your favorite, but lesser known Linux commands?

fuser, strace, ltrace, nc come to mind offhand.

xelfer• 18 years ago

lsof, ngrep, history (only found out this one a month ago after 6 years of being a sysadmin)

palish3• 18 years ago

What terrible names. Sorry, but from a non-Unix perspective, symbols such as 'lsof' and 'ngrep' seem arbitrary and nonsensical.

11ren5• 18 years ago

pgrep, pkill, rename

utnick• 18 years ago

not sure how well known this is but I use 'tee' alot

m0nty• 18 years ago

To get back a hosed screen, also try:

stty sane ^j

(That's Ctrl-j there.)

You might be flying blind, but just do it and you might get your screen back.

You probably know this, but to rescue a hosed system with Knoppix or similar live-cd:

- Boot from CD.

- Open root console.

- Mount your usual root partition: mount -t somefs /dev/hda1 /mnt/oldsys

- chroot /mnt/odlsys /bin/bash

Showed that to another admin who'd lost a production box, and his chin kind of hit the floor :) I gifted him the Knoppix disk... You can also use that to reset passwords (as per the article), by editing /etc/shadow or /etc/passwd in the /mnt/oldssys directory.

easyrider2• 18 years ago

A detailed article on rescuing a hosed system with Knoppix:

How Knoppix saved the day

http://www.dancingbison.com/writings/knopresc.txt

marbletiles• 18 years ago

# while [ 1 ]; do echo "All your drives are belong to us!"; sleep 30; done

Hee, things I didn't think I'd ever see on ibm.com, #12234 in a series.

People with company songbooks and nice ties must be spinning in their graves

Lazy Linux: essential tricks for admins

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