Daniel Lange's blog (Entries tagged as shell)

Generate an indexed list of passwords

nospam@example.com (Daniel Lange) — Sun, 09 Aug 2015 17:31:58 +0000

Generating an indexed list of passwords without complex perl or python:

pwgen -y 20 30 | nl -w 2 -n rz -s -

Explanation:

pwgen: -y = complex passwords (including symbols) ; 20 = length of password; 30 = number of passwords to generate

nl: -w 2 = zero pad to a width of two characters; -n rz = print right-justified; -s - = use dash as a separator

Managing a project consisting of multiple git repositories

nospam@example.com (Daniel Lange) — Thu, 05 Mar 2015 13:30:00 +0000

The core team organizing DebConf, the annual Debian developer conference, reached out to me two weeks ago to help support this year's effort a bit.

I'm very happy to do so as Debian is a cornerstone of everything I do in the Open Source/Free Software space.

To get me started I got access to a lot of mailing lists and irc channels. And even more git repositories. So many that the DebConf team even has an instruction page on how the repositories all fit together.

It's unfortunately quite common to split a bigger project into many git repositories to ease access rights management and reduce the noise and data transfer volume for the average user. The downside is, everybody ends up with a dozen or more individual repositories to keep pulling. And then there's git annex for yet another level of indirection.

Joey Hess, a former Debian developer, has even written an extensive tool, myrepos, to meta-manage the different repositories and it can do quite some magic across different SCMSs¹. In my case this is a bit of an overkill though.

And using myrepos may get you confused at some point whether to now run mr or git directly for each batch of repos you have inherited over some time of working on multiple projects.² Thus I prefer the simple route:

Check out each repository into a common top-level directory (~/debconf/ in this case) and then put the following two lines into an executable script git_pull_all into that top level directory:

#!/bin/sh
find ~/debconf -mindepth 1 -maxdepth 1 -type d -exec sh -c "cd {}; test -r .git/config && git pull $*" \;

This will allow you to pull all git repos with one command and keep the normal syntax for everything else you do with each repo.

The --mindepth and --maxdepth will instruct find to just go and run your git pull only inside each direct child of the top level directory. So recursion depth = 1. That is the single trick there is to this.

Updates:

If you like to have some color and a bit of a spaced layout for improved readability, try:

#!/bin/sh
find ~/debconf -mindepth 1 -maxdepth 1 -type d -exec sh -c "cd {}; test -r .git/config && (printf \"\033[1m\033[34m%-50s\033[0m\" \"\${PWD}:\" ; git pull $*)" \;

When you have pull.rebase=true set in your .gitconfig, you can run ./git_pull_all --no-rebase to avoid rebases in case you work somewhere and want to have the merge commits.

P.S.: The DebConf15 Heidelberg registration just opened, please check the DebConf15 homepage for news, venue information and please register if you want to come around.

Source Code Management Systems, like git, mercurial (hg) or subversion (svn). Or God forbid ... cvs. I don't like the (D)VCS (Distributed) Version Control Systems moniker. Because that's not really all these systems do. Not even the most important piece of what they do these days. ↩
With myrepos you can still work with each individual repository via git. Just so nobody will write in "but...". ↩

Apple iPhone ring tones Linux style

nospam@example.com (Daniel Lange) — Sun, 27 Mar 2011 09:55:00 +0000

Apple has crippled the iPhone to not allow normal music files as ringtones. Business decision. Technically any sub 40 second MP4 audio file will do once you rename it to *.m4r and drag-and-drop it to the ringtones folder of your phone in iTunes. Longer ones will work, too. But you'd need a jailbroken iPhone for that as iTunes will refuse to transfer the ringtone file if it's too long. Not much of an issue imho, who keeps ringing your phone for 40 seconds or more?

There's a gazillion websites available telling you how to convert a single .mp3-file to a ringtone with or without iTunes help and there are hundreds of tools doing that for you if you can't find out how to do it with just iTunes itself. Still the ones I tried failed for me as I wanted to convert my 20 or so standard ringtones from the good old Motorola K3 to iPhone ringtones all in one go. Without having to edit each one by hand. They are already nice ringtones and have served me well for years, just too long for the iPhone and in .mp3 format.

The basic processing sequence needed is

Cut the .mp3 down to 39s
Convert the .mp3 -> .wav (with mplayer, normalize output gain while we're at it)
Convert the .wav -> .mp4 (with facc)
Clean up, GOTO 1 for next file

So below is the free shell script to create multiple ringtones in one go on any Linux system. You need to install cutmp3, mplayer and faac for it, so apt-get install cutmp3 mplayer faac on Debian or Ubuntu. cutmp3 is currently not in the portage tree for Gentoo, but you can download an ebuild from Polynomial-C's overlay (mirror). Or you just download the cutmp3 binary from Jochen Puchalla's homepage. There's no error checking in the script, so know your way around the shell before running it.

Without further ado:

#!/bin/sh
#
# convert_to_ringtone file1.mp3 [file2.mp3, ...]
# Placed into the public domain by Daniel Lange, 2011.
#

for arg
do
echo "Processing $arg..."
cutmp3 -c -a 0:0.0 -b 0:39.0 -i "$arg" -O "$arg.tmp"
mplayer -vo null -vc null -af volnorm -ao pcm:fast:file=tmpfile.wav "$arg.tmp"
faac -b 128 -c 44100 -w tmpfile.wav
name=`echo $arg| sed 's/.mp3//g'| sed 's/ /_/g'`
mv tmpfile.m4a $name.m4r
rm tmpfile.wav
rm "$arg.tmp"
echo "$arg done."
done

Update

23.12.14 Apparently the faac package in Debian and Ubuntu has had the MP4 writing capability removed in v1.28-5 and later due to a minor license incompatibility. See the Debian Changelogs. Duh.

faac (1.28-5) unstable; urgency=low
  [ Andres Mejia ]
  * Disable mp4v2 support.
    This only disables mp4v2 for the faac utility program. The faac
    utility is GPL-2 but the mp4v2 library is MPL-1.1. The two licenses
    are incompatible with each other.

So ... unfortunately you have to built faac from source yourself or pin the v1.28-4 version which is identical except for the castration anyways.

Random distro dev: "Why oh why doesn't my distro ever head mainstream...?"
Hint: Because of stuff like this.