Useful Linux Scripts and Commands

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[[ http://student.northpark.edu/pemente/sed/ | Great SED Reference Site]]

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How to Create an ISO File in Linux
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[@
dd if=/dev/cdrom of=/cdrom_image.iso
@]

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Monitor the /home drive and report if its usage is greater than 80%.
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[@
#!/bin/bash

declare -i usage=0

usage=`df | grep "/home" | cut -c 52-54`
if [ $usage -gt 4 ]; then
du --max-depth=1 /home | mail -s "Warning: Usage of /home is above 80 percent" "brandtb"
fi
exit 0
@]

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Find the fully qualified host name of a system (i.e. host.domain.name)
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[@
function fullhostname {
domain=sed -n 's|^search\s\(.*\)|\1|p' /etc/resolv.conf | sed 's|\s.*||' | sed -n 's|\w\+\.\w\+|&|p'
if [ -n "$domain" ]; then
domain=".$domain"
fi
echo `hostname`"$domain"
}
@]

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function findpath() {
relativepath=`echo "$0" | sed -n 's|\(.*\)/.*|\1|p'`
pushd "$relativepath" > /dev/null ; pwd ; popd > /dev/null
}

function findname() { echo $0 | sed 's|.*/||' }

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Find a full path from a relative path
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[@

@]
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Find the name of a script file
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[@

@]

(:title Useful Linux Scripts and Commands :)

Display a Hex dump of a file
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[@
od -Ax -tx1z -v /path/to/filename
@]
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Trim Strings
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[@
# Front Trim
echo " the test " | sed 's/^[[:space:]]*//'

# Rear Trim
echo " the test " | sed 's/[[:space:]]*$//'

# Full Trim (the -e tells sed that there is more than one command)
echo " the test " | sed -e 's/^[[:space:]]*//' -e 's/[[:space:]]*$//'
@]
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Find out how many specific characters there are in a string (i.e. how many t's are in a test string)
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[@
char=t
numchar=`echo " the test string " | sed 's/[^$char]//g'`
numchar=${#numchar}
@]
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Search and replace text within a file
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[@
filename="$1"
searchtext="$2"
replacetext="$3"

sed 's~'"$searchtext"'~'"$replacetext"'~g' $filename
@]
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Make sure user is root
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[@
if [ "`id -u`" != "0" ]; then
echo "You must be root to run this script" && exit 1
fi
@]
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Ask for user input
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[@
##############################################################################
# Below is the code responsible for producing asking a question #
# #
# USAGE: userinput Question DefaultAnswer #
# #
##############################################################################
function userinput {
echo -e -n "$1 [$2]: "
read value
if [ -z "$value" ]; then
value=$2
fi
echo
}
@]
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Script to find all the MAC Addresses Of Windows PCs in an IP subnet.
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[@
#!/bin/bash

if [ "$1" == "" ]; then
echo -e "Used to create a CSV file of all the IP Addresses in the a subnet and the MAC\n addresses of those Windows IPs" 2>&1
echo -e "Usage: $0 aaa.bbb.ccc\n" 2>&1
exit 1
fi

for i in `seq 1 254`
do

ip="$1.$i"
if ping -c 1 $ip > /dev/null
then
result=`nmblookup -A $ip | grep "MAC Address = "`
if [ "$result" != "" ]; then
echo "\"$ip\", \"$result\""
fi
fi
done
exit 0
@]
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