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 -h alias .bash[r_][ca]* | sed 's/^[ ]*//' | egrep -v '^#' | sort -u >> tmp

The -h flag tells the first grep not to print the file name.

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