/home/drscream

In bash there is an easy way to generate a sequence of numbers or characters. By defining a start and stop character with the ‘..’ in between:

$ echo {a..z}
a b c d e f g h i j k l m n o p q r s t u v w x y z

The example above works with lower and upper case characters. Use upper and lower case characters in mix:

$ echo {A..z}
A B C D E F G H I J K L M N O P Q R S T U V W X Y Z [  ] ^ _ ` a b c d e f g h i j k l m n o p q r s t u v w x y z

It also work with numbers:

$ echo {0..9}
0 1 2 3 4 5 6 7 8 9
$ echo {0..22}
0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22

Another way to generate a list of numbers is using the command line tool seq:

$ seq 1 4
1
2
3
4

To change the delimiter you can use the parameter -s “delimiter”, for example with a space:

$ seq -s " " 1 10
1 2 3 4 5 6 7 8 9 10

Yes it’s mindless :-)

PS1='C:${PWD//\//\\\}>'

The code:

#/bin/bash

bashBox () {
	str="$@"
	len=$((${#str}+4))
	for i in $(seq $len); do echo -n "*"; done;
	echo; echo "* "$str" *";
	for i in $(seq $len); do echo -n "*"; done;
	echo
}

bashBox "Yea, a bash Box"

The output:

 % ./bashbox.sh
*******************
* Yea, a bash Box *
*******************

Yeaaa :-) Yesterday i’ve found a nice way to set an default value for bash variables.
I use this way if parameter 1 isn’t assigned by the user. Here a small example:

ip=${1-'10.1.1.1'}

If $1 isn’t assigned by the user the default 10.1.1.1 is set as value of $ip.

With find you can everything but you must know it :)

find . -type d -empty

[drscream@havanna] ~/Pictures/upload
 % find . -type d -empty
./Artwork/html/thumb
./Artwork/Photography/html/thumb
./html/thumb

It’s so easy, i’ve only searched a day long for that easy result:-P

[drscream@havanna] ~
 % tclsh
% puts $tcl_version
8.4

Currently i’ve some problems with my router. The reconnect only work sometimes… . So i’ve started to write a small bash script, to check that connection. The script run every hour and start a reconnection if no pppoe connection is available.

#!/bin/bash
#--------------------------------------------------------------------
# $Id: checkIConnect,v 0.1 2008/02/11 17:17:26 drscream Exp $
# Copyright 2008 Frubar Network (drscream@frubar.net)
#--------------------------------------------------------------------

##
## main
##
errors=0
ns_ip=$(cat /etc/resolv.conf | sed 's/nameserver //g' | head -n 1)

## device check
$(/sbin/ip a s dev ppp0 > /dev/null 2>&1)
if [ $? -gt 0 ]; then
        echo "ERROR: Device not found!"
        let errors=$errors+1
fi

## nameserver, ping check
$(ping -c 4 $ns_ip > /dev/null 2>&1)
if [ $? -gt 0 ]; then
        echo "ERROR: Ping doesn't work!"
        let errors=$errors+1
fi

echo "Code: $errors"

if [ $errors -gt 0 ]; then
        echo "INFO: reconnect internet"
        /opt/fruky/bin/pppoe-restart
fi

Easy way to get the last day is to look if the next day is the first of the month. Now here are a small bash script thats show you the functionality:

if [ $(date -d tomorrow +%d) -eq 1 ]; then
    echo "OK: last day of the month"
else
    echo "NOK: not the last day of the month"
fi

Wer kennt es nicht, gerade wenn man viele Datein loeschen moechte:

Argument list too long.

Ein einfacher “workaround” ist das verwenden von xargs:

ls | xargs rm

( Vielen Dank an adminlife.net )