HandsomePlanet

Stripping leading whitespace and comments with sed

In trying to consolidate some bash aliases (found in .bashrc and .bash_aliases), I needed to strip out comments and leading whitespace to sort for unique lines.

To strip spaces, I used
egrep alias .bashrc | sed 's/^[ ]*//'

To remove spaces and tabs in the whitespace (see info on tabs after this example):
egrep alias .bashrc | sed 's/^[ ]*//'
NOTE: In the expression, sed 's/^[ ]*//' , the expression in the brackets is actually a space followed by a tab. At the command line, I had to create the tab by typing Control-V and then hitting TAB on the keyboard. You may need to represent tabs in a different fashion.

To get rid of leading whitespace, comments, and indented comments, I settled on
egrep alias .bashrc | sed 's/^[ ]*//' | egrep -v '^#'

To gather and sort aliases from both .bash and .bash_aliases, then sending to a temporary file:
egrep alias .bash[r_][ca]* | sed 's/^[ ]*//' | egrep -v '^#' | sort -u >> tmp

Getting ‘Scroll Lock’ to work under Linux

I’ve got a couple of keyboards with Scroll Lock keys that are not functional by default under Linux.
For my Ubuntu systems, the following procedure worked to fix the problem. After this, the LED for scroll lock lights and the key function as expected.

The steps are as follows:

1. Find an unused modifier with xmodmap -p
2. Use xmodmap to assign Scroll_Lock to this modifier
3. Make the change persistent by adding it to your .Xmodmap file

First, use xmodmap -p to identify an unused mod key.
For example,

$ xmodmap -p
xmodmap: up to 4 keys per modifier, (keycodes in parentheses):

shift Shift_L (0×32), Shift_R (0x3e)
lock Caps_Lock (0×42)
control Control_L (0×25), Control_R (0×69)
mod1 Alt_L (0×40), Alt_R (0x6c), Meta_L (0xcd)
mod2 Num_Lock (0x4d)
mod3
mod4 Super_L (0×85), Super_R (0×86), Super_L (0xce), Hyper_L (0xcf)
mod5 ISO_Level3_Shift (0x5c), Mode_switch (0xcb)

mod3 is the open modifier. So, we’ll use it with xmodmap -e :

xmodmap -e "add mod3 =Scroll_Lock"

Capitalization is important, so “Scroll_Lock” has to be written exactly as printed.
You can have a space, or no space, after the equal sign.

Check that it works, then add the command content to your home directory (file does not have to exist):

echo "add mod3 =Scroll_Lock" >> ~/.Xmodmap

send man page to text file

Printing a manpage to a text file (perhaps more portable for cross-platform or bedtime reading):

generic Unix/Linux, using `col`:
man rcs | col -b > /tmp/man_rcs.txt

These alternatives would require that you reset PAGER or MANPAGER:
alternative BSD :
export MANPAGER=cat
man pf.conf > man_pf.conf.txt

alternative BSD :
export PAGER=cat
man pf.conf > man_pf.conf.txt

Ubuntu, Debian, Mint, etc. allow all of these alternatives:

-P pager, --pager=pager
Specify which output pager to use. By default, man uses pager -s. This option overrides the $MANPAGER environment variable, which in turn overrides the $PAGER environment variable. It is not used in conjunction with -f or -k.

recovering a complete config from rancid

pink noise

Pink noise can be used to mask distracting sounds in the environment around you. It can be useful for providing a neutral sonic background for concentration.

The program speaker-test comes in the alsa-utils package, and provides pink noise by default. This is described by its man page as “perceptually uniform noise”. There are a number of other options, but for a quick noise generator, speaker-test is very handy.

Command line fun for linux : included utilities

obelix@entity:~$ info util-linux-ng

What’s my ubuntu (or debian) version?

I have a  number of machines running various OS releases. Sometimes I need to check what flavor or relase I’m running on the current machine.
While uname -a will show the Linux kernel version, there are a few ways to get more information.
Here are three possibilities:
cat /etc/issue
cat /etc/lsb-release
and my favorite:
lsb_release -a

Here’s some sample output from lsb_release:
$ lsb_release -a
LSB Version: core-2.0-ia32:core-2.0-noarch:core-3.0-ia32:core-3.0-noarch:core-3.1-ia32:core-3.1-noarch:core-3.2-ia32:core-3.2-noarch:core-4.0-ia32:core-4.0-noarch
Distributor ID: Ubuntu
Description: Ubuntu 10.04.1 LTS
Release: 10.04
Codename: lucid

The “lsb” in these commands refers to the Linux Standard Base.  For more information, see the Linux Foundation .

lucidor

I’ve been looking at a number of different ebooks and e-readers lately.  Lucidor is a project which is a little better looking than some of the older apps, but it is still pretty early in development.

Here’s a copy of lucidor 0.9, which was difficult to find due to problems with the lucidor site:

lucidor_0.9-1_all.deb

md5sum:  08faa6b60df2dae654e70431aa2e7626  lucidor_0.9-1_all.deb.gz
sha1sum: 0397853f5c4fe013fe36aed71ec0aa219f7f35f2  lucidor_0.9-1_all.deb.gz

installing the development version of the sphinx documentation tool

Get the latest version from bitbucket:

$ hg clone http://bitbucket.org/birkenfeld/sphinx

The remainder of the instructions are based on the README, but details will vary according to what package dependencies need to be met. That is, some additional packages beyond what is described here may need to be installed.
Change to the new directory, build, and install.

cd sphinx
python setup.py build
sudo python setup.py install

Build sphinx’s documentation with sphinx:

cd doc
sphinx-build . _build/html

And, that should do it.

Also see the bitbucket sphinx wiki .

installing ntop on Ubuntu : problem with rrd directories

The ubuntu install for ntop is broken without some additional steps.

‘Ubuntu Bloke’ had the easy fix :

"Create the directories that for some reason are not created by the installer
sudo mkdir /var/lib/ntop/rrd
sudo mkdir /var/lib/ntop/rrd/graphics
sudo mkdir /var/lib/ntop/rrd/flows
sudo mkdir /var/lib/ntop/rrd/interfaces
sudo mkdir /var/lib/ntop/rrd/interfaces/eth0
sudo mkdir /var/lib/ntop/rrd/interfaces/ppp0
sudo chmod -R 775 /var/lib/ntop"