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In: Computer Science

Examine the following shell script and describe its function line-by-line: #! /bin/bash #This script backs up...

Examine the following shell script and describe its function line-by-line:

#! /bin/bash

#This script backs up the Oracle DB

rm -f /SAN/backup-oracle*

if tar -zcvf /SAN/backup-oracle- 'date +%F'.tar.gz/oracledb/*

then

echo "Oracle backup completed on 'date'" >>/var/log/oraclelog

else

echo "Oracle backup failed on 'date'" >>/var/log/oraclelog

mail -s ALERT [email protected] </var/log/oraclelog

fi

Expert Solution

#! /bin/bash

#This script backs up the Oracle DB

rm -f /SAN/backup-oracle*

if tar -zcvf /SAN/backup-oracle- 'date +%F'.tar.gz/oracledb/*

then

echo "Oracle backup completed on 'date'" >>/var/log/oraclelog

else

echo "Oracle backup failed on 'date'" >>/var/log/oraclelog

mail -s ALERT [email protected] </var/log/oraclelog

fi

#! /bin/bash

That is called a shebang, it tells the shell what program to interpret the script with, when executed.

#This script backs up the Oracle DB

This is a comment

rm -f /SAN/backup-oracle*

rm command is used to remove files in linux.
'-f' option in rm command will remove or delete the files forcefully regardless of its permissions and will also ignore non-existing files.

This will remove the files with name starting with 'backup-oracle' forcefully in the /SAN/ folder

if tar -zcvf /SAN/backup-oracle- 'date +%F'.tar.gz/oracledb/*

if the file is found this will work else it will go to else statement.
if tar -zcvf /SAN/backup-oracle will compress an entire directory and along with compression it will display the date shown in YYYY-MM-DD.

echo "Oracle backup completed on 'date'" >>/var/log/oraclelog

echo command in linux is used to display line of text/string that are passed as an argument .
>> is used to append to files.
This command will append ''Oracle backup completed on 'date'" along with date to the file oraclelog in the directory /var/log/.

else

If the previous code doesn't work, this code will run.

echo "Oracle backup failed on 'date'" >>/var/log/oraclelog

Which will append the line "Oracle backup failed on 'date'" to the oraclelog file in the /var/log/ directory

mail -s ALERT [email protected] </var/log/oraclelog

mail command is use to Send mails from command-line.
The s option specifies the subject of the mail followed by the recipient email address.
This command will send the ALERT to [email protected] and will redirect input to /var/log/oraclelog
< is used to redirect input to oraclelog file in the /var/log/ directory

fi will end the if statement

If you have any doubts, leave a comment below before rating. I'll be happy to assist you further.

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venereology answered 8 months ago

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