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Often find myself needing to do this but never remember how…

# flirble=(`ls -ltr ssh* | tail -3 | tr -s ' ' | cut -d ' ' -f 9` )
# echo ${flirble[*]}
ssh_host_key ssh_host_dsa_key.pub ssh_host_dsa_key
# echo ${flirble[0]}
ssh_host_key
# echo ${flirble[1]}
ssh_host_dsa_key.pub
# echo ${flirble[2]}
ssh_host_dsa_key
# echo ${flirble[3]}

# ls -ltr ssh* | tail -3
-rw-------  1 robin cm-users 539 Aug 11 12:40 ssh_host_key
-rw-r--r--  1 robin cm-users 614 Aug 11 12:40 ssh_host_dsa_key.pub
-rw-------  1 robin cm-users 668 Aug 11 12:40 ssh_host_dsa_key

This and more useful array manipulation can be found in Chapter 26 of the Advanced Bash Scripting Guide.

The sed regular expressions are essentially the same as the grep regular expressions. They are summarized below.

First, a nice css cheat sheet pdf:http://www.ilovejackdaniels.com/css_cheat_sheet.pdf

And secondly a nice colour picker dashboard widget http://www.colourmod.com/

If you are writing a bash script and you need to know where you are you can use this:

#!/bin/sh

# always prints out the directory in which this script is lives
# no matter where it is run from

# doesnt cope with ../bin/script.sh, which should be ./script.sh anyway

bn=`basename $0`;
echo $0 | grep "^/" > /dev/null 2>&1

if [ $? -eq 1 ]; then
 echo $0 | grep "^\.\/$bn" > /dev/null 2>&1
 if [ $? -eq 1 ]; then
   echo case 1 - relative ref
   here=`dirname $PWD/$0 | sed 's/\.\///'`
 else
   echo case 2 - local ref
   here=$PWD
 fi
else
 echo case 3 - root ref
 here=`dirname $0`
fi

echo script home is $here

Thanks to Justin for this

Found these two nice links this morning, first a very nice periodic table of perl operators and second, a useful little cgi that helps find out what is installed on your server.

Update: An anonymous commenter pointed out that bash has the ability to do this in a much shorter way:

BLAH=${BLAH:-no}

Job done!, my original older way is below…

[root@sn-b02 init.d]# echo $BLAH

[root@sn-b02 init.d]# [ "${BLAH}" = "" ] && export BLAH="no"
[root@sn-b02 init.d]# echo $BLAH
no
[root@sn-b02 init.d]#

When running a command in bash it will store the return code in the special variable $?, like this:

[robin@book robin]$ ls -ld tmp
drwxr-xr-x  3 robin  robin  1024 Aug  3 11:02 tmp
[robin@book robin]$ echo $?
0
[robin@book robin]$ ls -ld bob
ls: bob: No such file or directory
[robin@book robin]$ echo $?
1
[robin@book robin]$

When running a series of commands in a pipe however it is sometimes necerssary to find the return code of an individual command in the pipe, in this case bash stores the return codes in an array names $PIPESTATUS which you can access like any other bash array. The array can only be used once however, so if you want to use it more than once store it in some other temporary array.

[robin@book robin]$ echo "tmp"  | xargs ls -ld
drwxr-xr-x  3 robin  robin  1024 Aug  3 11:02 tmp
[robin@book robin]$ echo ${PIPESTATUS[@]}
0 0
[robin@book robin]$ echo "bob"  | xargs ls -ld
ls: bob: No such file or directory
[robin@book robin]$ echo ${PIPESTATUS[@]}
0 1
[robin@book robin]$ echo "bob"  | xargs ls -ld
ls: bob: No such file or directory
[robin@book robin]$ echo ${PIPESTATUS[1]}
1
[robin@book robin]$

Some perl that sets a timeout value

#!/usr/bin/perl

$SIG{ALRM} = sub { alarmed(); };

alarm(20);
eval { check_whatever; };
alarm(0);

sub check_whatever()
{
  # stuff to do that might timeout
  exit 0;
}

sub alarmed()
{
  # stuff to do after the alarm has gone off.
  exit 1;
}

Thanks to Timbo for help with this…

Nice examples of multi column css layout here

While researching css I’ve found this useful site with an amazingly useful css browser support chart