SHELL-1.1 Shell Script Introduction and Basics


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A shell script is basically a script that runs a bunch of unix commands along with conditional statements, loops statements. When programming shell script, space matters.
#!/bin/bash

# SETTING A VARIABLE
greeting=”Hello World”

# SETTING A GLOBAL/ENVIRONMENT VARIABLE
export blogname=”fuzicast”

# ASSIGN OUTPUT OF SUBSHELL TO VARIABLE
filenames=$(ls -ltr) # note that subshell inherits all environment variables from parent shell
no_of_files=`ls -ltr | wc -l`

# HOW TO CREATE MULTIPLE LINE COMMENT
<<COMMENT
The previous line begins a comment block, this is also known as HERE DOCUMENT
Here's another comment
The following line ends the comment block
COMMENT

# PERFORM ARITHMETIC CALCULATION
var1=45
var2=30
echo $[ $var1 + $var2 ]
(( sum=$var1 + $var2 ))
echo $sum

# IF STATEMENT
if [ $[ $var1 + $var2 ] -gt 70 ];then
echo "sum is greater than 70"
elif [ $[ $var1 + $var2 ] -lt 70 ];then
echo "sum is less than 70"
else
echo "unknown"
fi

# WHILE STATEMENT
var1=30
while [ $var1 -gt 0 ];do
echo "while \$var1 is greater than 0, keep running … "
var1=$[ $var1 – 1 ]
done

# UNTIL STATEMENT
var1=0
until [ $var1 -gt 30 ];do
echo "until \$var1 is greater than 30, keep running …"
var1=$[ $var1 + 1 ]
done

# FOR STATEMENT
for arg in $@;do
echo $arg
done

# CASE STATEMENT
var1=1
case $var1 in
1) echo "hello world"
echo "fuzicast video tutorials";;
2) echo "wrong option";;
3) echo "guess again";;
*) echo "Default option";;
esac

Fuzicast hits 5000+ views; New video on UNIX pipes and direction


Wow, after a little more than 2 months since inception of the blog, fuzicast.com now has over 100+ subscribers (twitter, youtube, facebook, wordpress), 5000+ views on the blog and more than 4000+ views on Youtube videos. Is it worth for a celebration? I say yes! But above all, this couldn’t have been done without all the viewers and subscribers. Thank you for making this happen. More videos will be coming out this weekend to celebrate! =)

PS: If you like the blog, please feel free to share fuzicast.com with your friends and coworkers. Also make sure to subscribe to my channel for more videos on UNIX, Perl and SQL.
facebook: facebook.com/fuzicast
twitter: @fuzicast
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