Stoppt die Vorratsdatenspeicherung! Jetzt klicken &handeln! Willst du auch an der Aktion teilnehmen? Hier findest du alle relevanten Infos und Materialien:
Jump to menu and information about this site.


Planet Commandline officially online //at 22:25 //by abe

from the Magrathea dept.

Around the first bunch of postings in my Useful but Unknown Unix Tools, Tobias Klauser of inotail and Symlink fame came up with the idea of making a Planet (i.e. a blog aggregator) of all the comandline blogs and blog categories out there.

A first Planet Venus running prototype based on the template and style sheets of Planet Symlink was quickly up and running.

I just couldn’t decide if I should use an amber or phosphor green style for this new planet. Marius Rieder finally had the right idea to solve this dilemma: Offer both, an amber and a phosphor green style. Christian Herzog pointed me to the right piece of code at A List Apart. So here is it, available in you favourite screen colors:

Planet Commandline

For a beginning, the following feeds are included:

Which leads us to the discussion what kind of feeds should be included in Planet Commandline.

Of course, all blogs or blog categories which (nearly) solely post neat tips and tricks about the command line in English are welcome.

Microblogging feeds containing (only) small but useful command line tips are welcome, too, if they neither permanently contain dozens of posts per day nor have a low signal-to-noise ratio. Unfortunately most groups do, so they’re not suitable for such a planet.

What I’m though unsure about are non-English feeds. Yes, there’s one in already, but I noticed this only after including Beat’s Chrütertee and his FreeBSD command line tips are really good. So if it doesn’t go overboard, I think it’s ok. If there are too many non-English feeds, I’ll probably split Planet Commandline off into at least three Planets: One with all feeds, one with English only and one with all non-English feeds or maybe even one feed per language. But for now that’s still a long way off.

Another thing I’m unsure about are more propgram specific blogs like the impressive Mastering Emacs blog “about mastering the world’s best text editor”. *g* (Yeah, I didn’t include that one yet. But as soon someone shows me the vi-equivalent of that blog, I’ll include both. Anyone thinks, spf13’s vim category is up to that?)

Oh, and sure, any shell-specific (zsh, tcsh, bash, mksh, busybox) tips & tricks blogs don’t count as program-specific blogs like some $EDITOR, $BROWSER, or $VCS specific blogs do. :-)

Of course I’m happy about further suggestions for feeds to include in Planet Commandline. Just remember that the feed should provide (at least nearly) exclusively command line tips, tricks or howtos. Suggestions for links to other commandline related planets are welcome, too.


Perfect Team: autossh and GNU Screen //at 01:06 //by abe

from the shell-functions-for-road-warriors dept.

SSH is definitely one of my most often used tools, not only for system administration at work but also on the road with my netbook, an EeePC 701 running Debian Sid.

On the road, it often happens that I have a flaky WLAN or UMTS connection, so I often have to kill (via <Enter>~.) and reconnect my SSH session due to a changed IP address or so.

First step against problems arising from using SSH over unreliable network connections is of course GNU Screen. Second step is use SSH keys and ssh-agent to not needing to type the password on every reconnect.

But it’s still very annoying to kill the SSH connection and call ssh again manually. For luck there is autossh, a wrapper around SSH which regularily checks via two tunnels connect to each other on the remote side if the connection is still alive, and if not, it kills the ssh and starts a new one with the same parameters (i.e. tunnels, port forwardings, commands to call, etc.).

It’s quite obvious that this is perfect to be combined with screen’s -R and -d options (Reattach if a detached screen is around, else start a new screen; detach a currently attached screen), so I found myself very often typing (or fetching it from the commandline history :-):

autossh -t 'screen -Rd'

-t is necessary to allocate a terminal device on the remote machine which is not done by default if you directly call a command via ssh.

In comparision to OpenSSH, autossh needs the single quotes, because otherwise it would parse -Rd as options to parse to ssh and bail out. That’s not a real problem, but when you’re used to just type ssh -t screen -Rd without any quotes, you’ll run into this then and when.

Update, 25-May-2010, 14:55: As Carsten Hey points out, autossh also supports the -- option to declare that all following options and parameters must be passed to ssh itself. (End of Update)

Typing that often and mistyping it then and when cries for an shell alias or an shell function. So I came up with the following shell function:

asc() {
    autossh -x -a -t "$@" 'screen -RdU'

I used a function instead of an alias in case of autossh will in future regard all parameters given after the command as part of the command as ssh does.

The additional options -x and -a disable X and SSH Agent forwarding which both don’t work if you reattach to an already running screen.

And if you’re using Zsh as I do, you can even add some more format string magic to set the window title more or less to the expanded alias, eh, function:

function asc() {
    # Set the title to something more obvious, e.g. the expanded
    # alias, eh, function
    print -Pn "\e]0;%n@%m: autossh -t $* 'screen -RdU'\a";
    autossh -x -a -t "$@" 'screen -RdU'
compdef asc=ssh

Update, 25-May-2010, 14:59: As Hauke points out in a comment, Zsh users should also declare that asc should have the same tab completion as ssh itself. The example above has been updated accordingly. (End of Update)

In the meantime on the EeePC I use asc on the commandline more often than ssh itself. And I nearly no more type autossh. (The most common exception here is autossh hostname tail -F /path/to/some/logfile.)

Using that function you can also add common ssh options for tunneling, etc. — I use it most often like this:

asc -D 1080

This opens a SOCKS proxy on localhost, port 1080 and that way I can surf via the host I’m connecting to by SSH.

There’s one small drawback though: You didn’t expect that I can just invent some new three letter command without a namespace clash, did you? There is a free game called Advanced Strategic Command whose binary (and Debian package) is named asc, too. If you have that game installed, you can always call it using its full path, e.g. /usr/games/asc on Debian.

P.S.: My whole grml based .zshrc is also available via git at as well as on github.

Multiple Move & Co. //at 00:08 //by abe

from the variations dept.

nion’s blog made me notice that many people don’t know mmv (multiple move), which approximately works like this:

mmv '*.htm' #1.html
mmv '*.foo.*' #1.#2.bla

Additionally, mmv also can copy, link or even append files when called as mcp, mln or mad respectively with the appropriate command line options.

When I told nion in IRC on about mmv, HE pointed me to the Perl script /usr/bin/rename, which is in Debian’s perl package and therefore installed on nearly every Debian system by default. It moves files by applying perl subsitutions to file names:

rename 's/\.htm$/.html/' *.htm
rename 'y/A-Z/a-z/' *

Being curious, if the newly found tool is not only available in Debian, I looked on a SuSE 9.0 box and indeed, I also found there a /usr/bin/rename. But — surprise, surprise — it’s not a Perl script but an ELF binary. And although it does similar things than mmv and Debian’s rename, it is the simplest of the three commands:

rename .htm .html *.htm
rename foo foo00 foo?
rename foo foo0 foo??

Note to my self: Nice add-on for your command line efficiency talk.

autossh vs TCP resetter //at 00:08 //by abe

from the lick-my-ass-script-kiddie dept.

LUG-Camp 2007 in Interlaken is nearly over, and I’m reading my mail as usual using ssh, screen and mutt on the server. But the ssh connection resets every few minutes. According to the LUSC people (who are running the gateway) some script kiddie is running a TCP resetter somewhere in the network.

I remembered that I read about autossh in the Debian package list once a while and that it sounded cool but I had no use for it yet. Until now.

I’m writing this over the same crashing ssh connection and I’m typing without taking big notice of the quite often occurring connection resets:

autossh -t 'screen -rd'

It just works. :-)


xen-tools 4.2 released //at 13:55 //by abe

from the finally-a-final dept.

Last night, I released xen-tools 4.2 and also uploaded it to Debian Unstable. It also should become part of the upcoming Debian stable release called Squeeze. (Thanks, Mehdi!)

For those who are missing xen-tools in Ubuntu 10.04 Lucid Lynx or Ubuntu 10.10 Maverick Meerkat, there’s now a xen-tools PPA containing the current stable package for both Ubuntu releases.

Major changes since the 4.2 release candidate 1:

  • Tons of documentation improvements
  • Preliminary support for Ubuntu 11.04 Natty Narwhal and Debian 7.0 Wheezy (Closes #597521)
  • More robustness on exotic combinations of command-line options

Major changes since 4.2 beta 1:

  • Uses GeoIP for Debian mirrors: Default Debian mirror is now
  • Uses apt-config to parse Dom0’s apt.conf. (Closes #560011)
  • With --verbose, the output of commands called by xen-tools (e.g. debootstrap) is not only logged, but also printed to STDOUT. (Closes #513126)
  • Adds btrfs support.

New Team Member

I’d also like to welcome Stéphane Jourdois as member of the xen-tools development team who contributed quite a lot of the new code in 4.2. See GitHub’s Impact Graph or Ohloh’s List of Contributors.


If there’s no need for a bug fix release, the next release will be 5.0 and will be the result of some heavy refactoring. Our aim is:

  • less code duplication
  • more modularity
  • more consistency over all included scripts and hooks

We will probably also use Perl::Critic to improve the code consistency and quality further. (Thanks Renée for the idea!)


Screen and Emacsclient: Automatically switching to the Emacs window //at 10:38 //by abe

from the desktop-comfort-in-text-mode dept.

For a very long time, I use mutt with emacsclient as configured editor and a single GNU Emacs instance started from either .screenrc or .Xsession, depending on the system. And I’m very used to switching the virtual desktop or the screen window after starting a mail in mutt.

Since Debian 5.0 Lenny and Emacs 22, Emacs automatically grabs the focus and switches to the right virtual desktop. So after telling mutt recipient and subject of a new e-mail, it invokes emacsclient and immediately the focus has moved to the running Emacs instance. Because I was used to switch one virtual desktop to the right at that point, I often found my self two desktops to the right until I got used to it. :-)

I usually hate applications which grab the focus without being asked. But in this case I basically asked for it. And there’s no delay like with starting up an application which has to read in some database first – think of Liferea or Rhythmbox which take many seconds to minutes to start up, even on my 2.2 GHz dual core ThinkPad.

In the meantime I got so used to that automatic desktop switch that I forget to switch the screen window in the second scenario where I use this combination: My screen doesn’t automatically switch to the Emacs window (window 1) after I told mutt recepient and subject in window 2.

Knowing that screen is quite scriptable, I found out that only a very small change is needed to my mutt configuration to get that desktop feature to my everyday screen session. I simply replaced the editor setting in my .muttrc with the following line:

set editor="screen -X select 1;emacsclient"

Now mutt tells screen to switch to window 1 (where Emacs is running) and then tells Emacs to open the appropriate file to edit my new mail.

Update Friday, 2009-04-24, 18:22

Even though Zack surely is right with his comment about the multi-terminal feature of the upcoming GNU Emacs 23, I still have Etch (and therefore GNU Emacs 21) on the server where I have my screen session.

So the next step was to switch back to the mutt window (window 2) after I’m finished with editing the mail. Since mutt gives the the file to edit as argument to the contents of $editor, simply adding ;screen -X select 2 at the end of $editor doesn’t suffice.

So I wrote a small shell script (named ~/.mutt/ as wrapper which calls all the commands and passes the parameters to the right command:


screen -X select 1
emacsclient -a ~/.mutt/ "$@"
screen -X select 2

Of course, $editor is now set to that script:

set editor="/home/abe/.mutt/"

Emacsclient of GNU Emacs 21 already supports the -a option to call another editor in case of not being able to connect to a running Emacs instance. Since I don’t want to switch to another screen window in that case, I wrote a second shell script (named ~/.mutt/ which switches back to the mutt window and then calls GNU Zile, my preferred low-end emacs clone:


screen -X select 2
zile "$@"
screen -X select 1

I love it!


Nice Shell Bloomer //at 16:39 //by abe

from the works-for-me dept.

While looking for users which still have “.” in their path, I found the following nice bloomer:


It’s obvious what the user tried to do. But why the fuck does this (more or less man or info page alike) quoting syntax work?

It took me a moment to realise that this kind of “quoting” works in nearly all Unix shells: The two backquotes as well as the two single quotes become an empty string and are therefor completely useless in this case.

The user probably read some uglily localized man or info page (like the German ones in Debian Sarge) and did some copy and paste to his .bashrc. And since it “worked” he didn’t see any reason to change it again.

Tag Cloud

2CV, aha, Apache, APT, aptitude, ASUS, Automobiles, autossh, Berlin, bijou, Blogging, Blosxom, Blosxom Plugin, Browser, BSD, CDU, Chemnitz, Citroën, CLI, CLT, Conkeror, CSS, CX, deb, Debian, Doofe Parteien, E-Mail, eBay, EeePC, Emacs, Epiphany, Etch, ETH Zürich, Events, Experimental, Firefox, Fläsch, FreeBSD, Freitagstexter, FVWM, Galeon, Gecko, git, GitHub, GNOME, GNU, GNU Coreutils, GNU Screen, Google, GPL, grep, grml, gzip, Hackerfunk, Hacks, Hardware, Heise, HTML,, IRC, irssi, Jabber, JavaShit, Kazehakase, Lenny, Liferea, Linux, LinuxTag, LUGS, Lynx, maol, Meme, Microsoft, Mozilla, Music, mutt, Myon, München, nemo, Nokia, nuggets, Open Source, Opera, packaging, Pentium I, Perl, Planet Debian, Planet Symlink, Quiz, Rant, ratpoison, Religion, RIP, Sarcasm, Sarge, Schweiz, screen, Shell, Sid, Spam, Squeeze, SSH, Stoeckchen, Stöckchen, SuSE, Symlink, Symlink-Artikel, Tagging, Talk, taz, Text Mode, ThinkPad, Ubuntu, USA, USB, UUUCO, UUUT, VCFe, Ventilator, Vintage, Wahlen, Wheezy, Wikipedia, Windows, WML, Woody, WTF, X, Xen, zsh, Zürich, ÖPNV


← 2020 →
OctNov Dec
 October →
Mo Tu We Th Fr Sa Su
20 21 22 23 24 25
26 27 28 29 30 31  

Tattletale Statistics

Blog postings by posting time
Blog posting times this month


Advanced Search


Recent Postings

13 most recent of 18 postings total shown.

Recent Comments

Hackergotchi of Axel Beckert


This is the blog or weblog of Axel Stefan Beckert (aka abe or XTaran) who thought, he would never start blogging... (He also once thought, that there is no reason to switch to this new ugly Netscape thing because Mosaïc works fine. That was about 1996.) Well, times change...

He was born 1975 at Villingen-Schwenningen, made his Abitur at Schwäbisch Hall, studied Computer Science with minor Biology at University of Saarland at Saarbrücken (Germany) and now lives in Zürich (Switzerland), working at the Network Security Group (NSG) of the Central IT Services (Informatikdienste) at ETH Zurich.

Links to internal pages are orange, links to related pages are blue, links to external resources are green and links to Wikipedia articles, Internet Movie Database (IMDb) entries or similar resources are bordeaux. Times are CET respective CEST (which means GMT +0100 respective +0200).

RSS Feeds

Identity Archipelago

Picture Gallery

Button Futility

Valid XHTML Valid CSS
Valid RSS Any Browser
This content is licensed under a Creative Commons License (SA 3.0 DE). Some rights reserved. Hacker Emblem
Get Mozilla Firefox! Powered by Linux!
Typed with GNU Emacs Listed at Tux Mobil
XFN Friendly Button Maker


People I know personally

Other blogs I like or read

Independent News

Interesting Planets

Web comics I like and read

Stalled Web comics I liked

Blogging Software

Blosxom Plugins I use

Bedside Reading

Just read

  • Bastian Sick: Der Dativ ist dem Genitiv sein Tod (Teile 1-3)
  • Neil Gaiman and Terry Pratchett: Good Omens (borrowed from Ermel)

Currently Reading

  • Douglas R. Hofstadter: Gödel, Escher, Bach
  • Neil Gaiman: Keine Panik (borrowed from Ermel)

Yet to read

  • Neil Stephenson: Cryptonomicon (borrowed from Ermel)

Always a good snack

  • Wolfgang Stoffels: Lokomotivbau und Dampftechnik (borrowed from Ermel)
  • Beverly Cole: Trains — The Early Years (getty images)