serfGeek's Geek::Blog

Wednesday, January 25, 2006

Tuesday, January 17, 2006

Files with spaces in their names...

If you want to process the output of find and some files have spaces in their names, you don't need to use double quotes...

find has the -print0 switch and xargs has the -0 (or --null) switch.

find . -type f -print0 | xargs -0 ls -l

Monday, January 09, 2006

Debian public key expired...


Reading package lists... Done
W: GPG error: http://ftp.uk.debian.org testing Release: The following signatures couldn't be verified because the public key is not available: NO_PUBKEY 010908312D230C5F
W: You may want to run apt-get update to correct these problems

and something like this:


10 upgraded, 0 newly installed, 0 to remove and 2 not upgraded.
Need to get 0B/14.7MB of archives.
After unpacking 557kB of additional disk space will be used.
Do you want to continue [Y/n]? 
WARNING: The following packages cannot be authenticated!
  apt apt-utils libgimp2.0 gimp-svg gimp gimp-data
Install these packages without verification [y/N]? 
E: Some packages could not be authenticated

This page explains it:

http://secure-testing-master.debian.net/

And this year (2006) while the link on the secure-testing page is still out of date, you can fix it with this:


gpg --keyserver subkeys.pgp.net --recv-keys 084750FC01A6D388A643D869010908312D230C5F
gpg --export 084750FC01A6D388A643D869010908312D230C5F | sudo apt-key add -

(thanks to #debian irc channel on freenode.net)

NB1: This will only work this year (2006) - because next year's key signiture will be different.

NB2: This has the side effect of adding the public key to root's keyring which you can see with:


gpg --list-keys

which gives:


pub   1024D/2D230C5F 2006-01-03 [expires: 2007-02-07]
uid                  Debian Archive Automatic Signing Key (2006)

You may want to remove it from there once you've imported it into apt, you can do this with:


gpg --delete-key 2D230C5F

Monday, November 28, 2005

Decimal to Binary

Crazy...

I've always had access to Perl (well since I started using Linux in 1994) and yet I've laboured over writing things in C sometimes... like maths stuff! - fancy spending days writing and months tweaking a command line calculator program in C... now I have this *massive* perl script:


#!/usr/bin/perl -w
die "Usage: $0 MATHS\n" unless(@ARGV);for(@ARGV){s/x/*/g};
print eval(join('',@ARGV)),$/;

To convert a decimal number to binary in perl you could do:


unpack("B32", pack("N", $number));

and then chopping off the leading zeros... as per http://www.unix.org.ua/orelly/perl/cookbook/ch02_05.htm

... but TIMTOWTDI, you're better to use:


sprint("%08b", $number);

Wednesday, November 23, 2005

Multi line comments in Perl...

How-can-I-comment-out-a-large-block-of-Perl-code?

or even just...


=pod
blah
blah
blah
~
~
~
=cut

...from http://mail.pm.org/pipermail/nwarkansas-pm/2000-September/000001.html


serf 2005-11-23 14:02:41-05 is =pod ... =cut still OK? or is that deprecated? 
serf 2005-11-23 14:03:28-05 I found it here 
ysth 2005-11-23 14:08:50-05 serf that will confuse any pod parser trying to look for documentation interspersed with your code; =for comment...=end comment =cut is better

http://perldoc.perl.org/perlpod.html

Prompt...

ksh and bash together:


PS_LOG_HOST="$LOGNAME@`hostname`:"
PS_TTY="[`tty|cut -c 6-`]"
case "$TERM" in
"xterm" | "screen" )
      BEL=`printf "\a"`
      if [ -n "${BASH_VERSION}" ]
      then
            PS1='\e]0;\u@\h:\w ${PS_TTY}\a\u@\h:\w ${PS_TTY}\n\$ '
      else
            PS0=`printf "\033]0;"`
            PS_KSH=`printf " (\033[01;31mksh\033[00m)"`
            PS1=$PS0$PS_LOG_HOST'$PWD '$PS_TTY$BEL$PS_LOG_HOST'$PWD '$PS_TTY$PS_KSH"
\$ "
      fi
;;
* )
      PS1=$LOG_HOST'$PWD$ '
;;
esac

You could trim the tty with ${MY_TTY:5}
but that substitution fails on ksh88:


ksh: ${MY_TTY:5}: bad substitution

bash:


case $TERM in
xterm )
      MYTTY=$(tty)
      PS1='\e]0;\u@\h:\w [${MYTTY:5}]\a\u@\h:\w [${MYTTY:5}]\n\$ '
;;
* )
      PS1='\u@\h:\w\n\$ '
;;
esac

ksh:


PS_LOG_HOST="$LOGNAME@`hostname`:"
case "$TERM" in
"xterm" | "screen" )
      BEL=`printf "\a"`
      PS0=`printf "\033]0;"`
      PS_TTY="[`tty|cut -c 6-`]"
      PS_KSH=`printf " (\033[01;31mksh\033[00m)"`
      PS1=$PS0$PS_LOG_HOST'$PWD '$PS_TTY$BEL$PS_LOG_HOST'$PWD '$PS_TTY$PS_KSH"
\$ "
;;
* )
      PS1=$PS_LOG_HOST'$PWD$ '
;;
esac

Tuesday, November 22, 2005

Supress count in isql

To supress "X rows affected" from printing with isql, do:


set nocount on

before the select

Friday, November 18, 2005

Sybase TLI

http://www.outlands.demon.co.uk/sybase/

Tuesday, November 08, 2005

Excel keyboard shortcuts...

The one I wanted to know was to delete a cell (or a column or row)... because <Delete> just clears the cell contents...

The keyboard shortcut is <Ctrl--> (Control+Minus) (Hyphen)

http://www.ozgrid.com/Excel/ExcelKeyBoardShortcutKeys.htm

Monday, November 07, 2005

Replacing with ^M in vim

If you want to remove ^M (<Ctrl-M> or Carriage Return) in vim (or vi) you can just do:


s/^M//g

To get the ^M use ^V^M

If you do


s/<TEXT>/^M/g

the <TEXT> is replaced with a newline character (i.e. ^J or \n) instead :o(

If you want to replace text with an actual ^M do:


s/<TEXT>/\^M/g


Of course if you're on Windows using gvim the ^V^M doesn't work, it's just the same as pressing  -

on Windows you need to use CTRL-Q instead of CTRL-V to escape the special character on the ex command line or to do a blockwise visual selection From the documentation: (usr_24.txt) Note: On MS-Windows CTRL-V is used to paste text. Use CTRL-Q instead of CTRL-V. On Unix, on the other hand, CTRL-Q does not work on some terminals, because it has a special meaning. (gui_w32.txt) *CTRL-V-alternative* *CTRL-Q* Since CTRL-V is used to paste, you can't use it to start a blockwise Visual selection. You can use CTRL-Q instead. You can also use CTRL-Q in Insert mode and Command-line mode to get the old meaning of CTRL-V. But CTRL-Q doesn't work for terminals when it's used for control flow.