Question

I’m trying to learn some scripting however I can’t find solution for one functionality.

Basically I would like to ask to evaluate my script as it’s probably possible to reduce the complexity and number of lines.

The purpose of this script is to download random, encrypted MySQL backups from Amazon S3, restore the dump and run some random MySQL queries.

I’m not sure how to email the output from printf statements – one is for headers and second one for actual data. I’ve tried to format the output so it looks like below but I had to exclude the headers from the loop:

Database:   Table:          Entries:                      

database1   random_table        0                             
database2   random_table        0                             
database3   random_table        0
database4   random_table        0

I would like to include this output in the email and also change the email subject based on the success/failure of the script.

I probably use to much if loops and MySQL queries are probably to complicated.

Script:

#!/usr/bin/env bash

# DB Details:
db_user="user"
db_pass="password"
db_host="localhost"

# Date
date_stamp=$(date +%d%m%Y)

# Initial Setup
data_dir="/tmp/backup"

# Checks
if [ ! -e /usr/bin/s3cmd ]; then
    echo "Required package (http://s3tools.org/s3cmd)"
    exit 2
fi
if [ -e /usr/bin/gpg ]; then

    gpg_key=$(gpg -K | tr -d "{<,>}" | awk '/[e-mail]/ { print $4 }')

    if [ "$gpg_key" != "[e-mail]" ]; then
        echo "No GPG key"
        exit 2
    fi

else
    echo "No GPG package"
    exit 2
fi

if [ -d $data_dir ]; then
    rm -rf $data_dir/* && chmod 700 $data_dir
else
    mkdir $data_dir && chmod 700 $data_dir
fi

# S3 buckets
bucket_1=s3://test/

# Download backup

for backup in $(s3cmd ls s3://test/ | awk '{ print $2 }')
do
    latest=$(s3cmd ls $backup | awk '{ print $2 }'  | sed -n '$p')
    random=$(s3cmd ls $latest | shuf | awk '{ print $4 }' | sed -n '1p')
    s3cmd get $random $data_dir >/dev/null 2>&1
done

# Decrypting Files
for file in $(ls -A $data_dir)
do
    filename=$(echo $file | sed 's/\.e//')
    gpg --out $data_dir/$filename --decrypt $data_dir/$file >/dev/null 2>&1 && rm -f $data_dir/$file
    if [ $? -eq 0 ]; then

        # Decompressing Files
        bzip2 -d $data_dir/$filename
        if [ $? -ne 0 ]; then
            echo "Decompression Failed!"
        fi
    else
        echo "Decryption Failed!"
        exit 2
    fi
done

# MySQL Restore

printf "%-40s%-30s%-30s\n\n" Database: Table: Entries:

for dump in $(ls -A $data_dir)
do
    mysql -h $db_host -u $db_user -p$db_pass < $data_dir/$dump
    if [ $? -eq 0 ]; then

        # Random DBs query
        db=$(echo $dump | sed 's/\.sql//')
        random_table=$(mysql -h $db_host -u $db_user -p$db_pass $db -e "SHOW TABLES" | grep -v 'Tables' | shuf | sed -n '1p')
        db_entries=$(mysql -h $db_host -u $db_user -p$db_pass $db -e "SELECT * FROM $random_table" | grep -v 'id' | wc -l)

        printf "%-40s%-30s%-30s\n" $db $random_table $db_entries

        mysql -h $db_host -u $db_user -p$db_pass -e "DROP DATABASE $db"     
    else
        echo "The system was unable to restore backups!"
        rm -rf $data_dir
        exit 2
    fi
done

#Remove backups
rm -rf $data_dir

Answer 1

move out of the loop :

random_tables=$(mysql -h $db_host -u $db_user -p$db_pass $db -e "SHOW TABLES" | grep -v 'Tables')
table_nb=$(wc -l <<<"$random_tables")

and in the loop

random_table=$(sed -n $((RANDOM%table_nb+1))p <<<"$random_tables")

A remark $? is the status of latest command executed so after && rm it will not be the status of decrypt