As a note-to-self, I’m placing it in my collection of useful tech tips since their library and documentation is more than useful.

And yes, I’m committing to participate there as well, although I don’t know when I’ll be able to send my first contribution.

But committmen is a start, right?

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This time the need was to add a series of users in a Linux system without repeating the command useradd one zirillion of times.

First, we need to populate a text files with details about the users we’re going to create.

Let’s assume the file is called myuserlist.txt (permissions 600) with the following syntax:

user1:password1:1001:510:My First Account:/home/user1:/bin/bash
user2:password2:1002:510:My Second Account:/home/user2:/bin/bash
user3:password3:1003:510:My Third Account:/home/user3:/bin/bash
user4:password4:1004:510:My Fourth Account:/home/user4:/bin/bash

Once you’re done with the list, proceed to add the users with the command:

newusers myuserlist.txt

After command is issued, check the results in the following files:

/etc/passwd
/etc/shadow
/etc/groups

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I tried to set it up on a VIA based appliance with Intel 1 Ghz processor and 1 Gb RAM, using 1 Gb Compact Flash and the image provided in download section of Zeroshell web site.

Everything went smooth, except that when I booted the appliance the BIOS information was displayed correctly, but as soon as Zeroshell boot started I saw crappy characters on screen.

After some investigation and some good hints from a friend, I found where the problem was and, as usual, here’s a tech note to avoid again this investigation in the future.

The issue was that appliance BIOS was set to redirect console to serial port with settings normally in use: 9600 bps, 8N1

…while Zeroshell defaults in its boot to more performing (but also less “default”) 38400.

To solve, remember to set your serial com port with correct speed as shown below (screenshot from a Win 7 box):

Or change the setting of the Terminal emulation software you are using to match the settings, as shown below (example with Putty):

Once you’re done, Zeroshell screen will appear as shown below:

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But I’m talking aout the other way around: haveing your modern MacBook booting in 64 bit mode, and possibly turn it into 32 bit only when you need it (sure, by keeping 3 and 2 pressed while booting).

Here’s howto:

1. Check your Mac is capable of doing it by issuing in terminal the command:
   ioreg -l -p IODeviceTree | grep firmware-abi
2. If output is something like “| |   “firmware-abi” = <”EFI64″>” this means Yes, you can!
3. Open a Terminal and cd to /Library/Preferences/SystemConfiguration/
4. edit com.apple.Boot.plist
5. under Kernel Flags insert
   arch=x86_64
   between the <string> and </string> tags
6. reboot
7. Enjoy

Of course, a good pre-check if you could be fine is to boot keeping pressed 6 and 4… if it boots 64bit then you’re ok.

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The command line is:

openssl x509 –req –in <path>/<certificate_request>.csr  –signkey <path-to-CA-private-cert>/CA-private-cert.pem –out <path-to-certs-repository>/signed-cert-name.pem

Hopefully next time I do not have to search it again hours and hours

Naturally this command required to have created the request before, and to have correctly setup the CA… but there is documentation on the ‘Net concerning these two operations.

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Question: I have a .ISO file representing the image of a DVD and I want to know the LABEL of that DVD.

Answer: Issue the command

dd if=/<path>/filename.iso bs=1 skip=32808 count=32

on whatever Linux terminal.

For example, here’s what is returned for a backup copy of DVD I legally own:

Input command:
dd if=Natale\ in\ Casa\ Muppets.iso bs=1 skip=32808 count=32

Output:
MUPPETS_CHRISTMAS_CAROL         32+0 records in
32+0 records out
32 bytes (32 B) copied, 0.00129793 s, 24.7 kB/s

Enjoy!

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The name of the thing is LLink and although I haven’t exploited at full yet, it looks VERY promising.

Some features:

• Parses various video containers: vob, avi, ts, mkv, tp, mov, m2ts, evo.
• Streams any file type the NMT player can handle: mp3, flac, jpeg, png etc.
• Can play straight from rar files: no more need to unrar your media. (Comes with special unrar-3.7.8-seek.)
• SSDP / UPnP discovery support (although minimal).
• Skin support: make your own html templates or choose from pre-built.
• Simple iMDb querying to look up media information for Jukebox skins.
• Both HD and SD skins available.
• Light, tiny and clean code for Unix, OsX and Windows.
• Paginating: support to send listings in pages, with tags for Next/Prev.
• PlayAll cgi tag, and PlayAllFrom.
• External subtitles: subtitle files can be consolidated in one directory.
• libdvdnav support (and libdvdcss): provides basic playback of DVD .iso and .img files and from DVD drives.
• UDF 2.50 BD5-ISO support: provides basic playback of Bluray and HD-DVD.

Got interested? You can find more here.

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Give a look to the script below, which I’m writing here for future reference.

#!/bin/bash
#
# This script creates a list of file or symbolic link to pictures in a directory
# The pictures are dynamically selected within a library of thousands
# This is to allow a wireless frame to display daily an ever changing list
# of pictures

# Define variable to be the target directory where we put the link/pictures
# This directory is regularly scanned by MediaTomb, the uPnP server talking to
# the digital frame

# Define variable to be the root directory where it will start to scan
scandir=/media/allphotos

# Clean previous contents of the directory used for streaming
cd /var/streampix
rm -rf *

# Define cycle to set the max number of photos to be displayed
# (like from 1 to 50 repeat)
for i in `seq 1 50`

# list the dir, pick a random file, add to the list
do
y="$(find $scandir -type f -iregex ‘.*\.\(bmp\|gif\|jpg\|png\)$’ | sort -R | head -1)"
cp "$y" /var/streampix/
done

Enjoy!

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