Bai tap voi shell script nhom10

Make sure the script runs in the bash shell.. Make sure the script runs in the Korn shell.. $ cat first.bash #!/bin/ksh echo Antwerp Note that while first.bash will technically work as a

sourLab 4: Working With Shell Script

Goal: In this lab, you will learn how to write a shell script.

1 Introduction to scripting

1 Write a script that outputs the name of a city.

$ echo 'echo Antwerp' > first.bash

$ chmod +x first.bash

$ /first.bash

Antwerp

2 Make sure the script runs in the bash shell.

$ cat first.bash

#!/bin/bash

echo Antwerp

3 Make sure the script runs in the Korn shell.

$ cat first.bash

#!/bin/ksh

echo Antwerp

Note that while first.bash will technically work as a Korn shell script, the name ending

in bash is confusing.

4 Create a script that defines two variables, and outputs their value.

$ cat second.bash

#!/bin/bash

var33=300

var42=400

echo $var33 $var42

5 The previous script does not influence your current shell (the variables do not exist outside of the script) Now run the script so that it influences your current shell.

source second.bash

6 Is there a shorter way to source the script ?

./second.bash

7 Comment your scripts so that you know what they are doing.

$ cat second.bash

#!/bin/bash

# script to test variables and sourcing

# define two variables

var33=300

var42=400

# output the value of these variables

echo $var33 $var42

2 Scripting tests and loops

1 Write a script that uses a for loop to count from 3 to 7.

#!/bin/bash

for i in 3 4 5 6 7

do

echo Counting from 3 to 7, now at $i

done

2 Write a script that uses a for loop to count from 1 to 17000.

#!/bin/bash

for i in `seq 1 17000`

do

echo Counting from 1 to 17000, now at $i

done

3 Write a script that uses a while loop to count from 3 to 7.

#!/bin/bash

i=3

while [ $i -le 7 ]

do

echo Counting from 3 to 7, now at $i

let i=i+1

done

4 Write a script that uses an until loop to count down from 8 to 4.

#!/bin/bash

i=8

until [ $i -lt 4 ]

do

echo Counting down from 8 to 4, now at $i

let i=i-1

done

5 Write a script that counts the number of files ending in txt in the current directory.

#!/bin/bash

let i=0

for file in *.txt

do

let i++

done

echo "There are $i files ending in txt"

6 Wrap an if statement around the script so it is also correct when there are zero files ending in txt.

#!/bin/bash

ls *.txt > /dev/null 2>&1

if [ $? -ne 0 ]

then echo "There are 0 files ending in txt"

else

let i=0

for file in *.txt

do

let i++

done

echo "There are $i files ending in txt"

fi

3 Parameters and options

1 Write a script that receives four parameters, and outputs them in reverse order.

echo $4 $3 $2 $1

2 Write a script that receives two parameters (two filenames) and outputs whether those files exist.

#!/bin/bash

if [ -f $1 ]

then echo $1 exists!

else echo $1 not found!

fi

if [ -f $2 ]

then echo $2 exists!

else echo $2 not found!

fi

3 Write a script that asks for a filename Verify existence of the file, then verify that you own the file, and whether it is writable If not, then make it writable.

4 Make a configuration file for the previous script Put a logging switch in the config

file, logging means writing detailed output of everything the script does to a log file

in /tmp.

4 More scripting

1 Write a script that asks for two numbers, and outputs the sum and product (as shown here).

Enter a number: 5

Enter another number: 2

Sum: 5 + 2 = 7

Product: 5 x 2 = 10

#!/bin/bash

echo -n "Enter a number : "

read n1

echo -n "Enter another number : "

read n2

let sum="$n1+$n2"

let pro="$n1*$n2"

echo -e "Sum\t: $n1 + $n2 = $sum"

echo -e "Product\t: $n1 * $n2 = $pro"

2 Improve the previous script to test that the numbers are between 1 and 100, exit with an error if necessary.

echo -n "Enter a number between 1 and 100 : "

read n1

if [ $n1 -lt 1 -o $n1 -gt 100 ]

then

echo Wrong number

exit 1

fi

3 Improve the previous script to congratulate the user if the sum equals the product.

if [ $sum -eq $pro ]

then echo Congratulations $sum == $pro

fi

4 Write a script with a case insensitive case statement, using the shopt nocasematch option The nocasematch option is reset to the value it had before the scripts started.

#!/bin/bash

#

# Wild Animals Case Insensitive Helpdesk Advice

#

if shopt -q nocasematch; then

nocase=yes;

else

nocase=no;

shopt -s nocasematch;

fi

echo -n "What animal did you see ? "

read animal

case $animal in

"lion" | "tiger")

echo "You better start running fast!"

;;

"cat")

echo "Let that mouse go "

;;

"dog")

echo "Don't worry, give it a cookie."

;;

"chicken" | "goose" | "duck" )

echo "Eggs for breakfast!"

;;

"liger")

echo "Approach and say 'Ah you big fluffy kitty.'"

;;

"babelfish")

echo "Did it fall out your ear ?"

;;

*)

echo "You discovered an unknown animal, name it!"

;;

esac

if [ nocase = yes ] ; then

shopt -s nocasematch;

else

shopt -u nocasematch;

fi

Scoring

 Part 1 - 25%

 Part 2 - 25%

 Part 3 - 25%

 Part 4 - 25%