How can this backup script be improved?

Question

ruby

Good day.
Wrote a script to back up the contents of the network share in the office.
Since I have not done this before (ready-made solutions like flexbackup were used), I would like to hear if the backup method given in it is good and how it can be improved.
Thanks in advance.
Script Code

require 'fileutils'
# We will keep 30 latest data snapshots
FileUtils.rm_r '/ext/30', :force => true
# Here we delete the oldest snapshot
range = (1..29).to_a.reverse # Literally the same as (29..1)
for i in range
  FileUtils.mv "/ext/#{i}","/ext/#{i+1}"
  # Shift backup one position to the past
  # Folder 1 becomes folder 2, folder 28 becomes folder 29, etc
end
%x[cp -al /ext/0 /ext/1]
# -a means archive: we go recursively through
# the directory tree, preserving permissions, access dates, etc
# -l means hardlinking: together with -a we create an
# illusion of the directory tree with the hardlinks to
# real files inside
%x[rsync -ae ssh --delete [email protected]:/shares /ext/0]
# We update the 0 folder with the latest data

Answer 1

In one of my publications, a scheme for processing video from webcams to FTP is described.
Everything is documented and commented there, you can look and correct it for yourself, if you wish.

Answer 2

Now I use this method previously described on Habré, it works quickly and has never failed

backup.sh

#!/bin/sh

. /usr/local/sbin/backup_functions.sh
BACKUP_EXPIRES_DAYS=0
# резерв 30Гб
RESERVE_G=4
BACKUP_MAIN_DIR='/media/backup'
VERIFY_BACKUP_MOUNTED='yes'
prepare_for_backup
cd /
make_backup etc boot home root opt srv usr/local /var
#make_backup_with_delta home/123 var/www

backup_functions.sh

#!/bin/sh

export LC_ALL=en_US.utf8
DIR_PATTERN='20..-..-..'
CURR_DATE=`date +%F`
RESERVE_G=5
BACKUP_MAIN_DIR='/backup'
BACKUP_TMP_DIR='/tmp'
BACKUP_DELTA=$BACKUP_TMP_DIR/backup.delta
BACKUP_ERRORS=$BACKUP_TMP_DIR/backup.err
BACKUP_REPORT=$BACKUP_TMP_DIR/backup.report
BACKUP_LOG_FACILITY='user.notice'
BACKUP_EXPIRES_DAYS=0
VERIFY_BACKUP_MOUNTED='no'
PID_FILE='/var/run/backup.pid'
BACKUP_MYSQL_DIR=$BACKUP_TMP_DIR/mysql_dump
MYSQL_DATA_DIR='/var/lib/mysql'

touch /etc/default/backup_exclude
rm $BACKUP_DELTA $BACKUP_ERRORS $BACKUP_REPORT 1>/dev/null 2>/dev/null

verify_backup_mounted() {
 mount -a
 [ -d "$BACKUP_MAIN_DIR" ] || { echo "BACKUP main directory does not exist!"; exit; }
 str=`df "$BACKUP_MAIN_DIR" | tail -1 | grep ' /$'`
 [ "$str" ] && { echo 'BACKUP partition is not mounted!!!!!!!!'; exit; }
 return 0
}
prepare_for_backup() {
 if [ -s "$PID_FILE" ] && [ `cat "$PID_FILE"` -ne $PPID ]
 then
 if [ "`ps ax | awk '{print $1;}' | grep -f \"$PID_FILE\"`" ]
 then
 echo -n "Previous BACKUP script is still running. PID = "; cat "$PID_FILE"; exit
 else
 logger -t BACKUP -p $BACKUP_LOG_FACILITY "Previous BACKUP ended unexpectly"
 fi
 fi
 rm "$PID_FILE" 1>/dev/null 2>/dev/null
 echo $PPID > "$PID_FILE"
 old_dir=`pwd`
 cd "$BACKUP_MAIN_DIR" || { echo "BACKUP main directory does not exist!"; exit; }
 VERIFY_BACKUP_MOUNTED=`echo "$VERIFY_BACKUP_MOUNTED" | tr 'A-Z' 'a-z'`
 [ "$VERIFY_BACKUP_MOUNTED" = "yes" ] && verify_backup_mounted
 reserve_k=$(($RESERVE_G * 1048576))
 mkdir -p $BACKUP_TMP_DIR 1>/dev/null 2>/dev/null
 dirs_list=`ls | grep $DIR_PATTERN | sort`
 if [ -n "$dirs_list" ]
 then
 while { free_k=`df -k .|grep -v Filesystem| sed -e "s/.\+ \([0-9]\+\) .\+/\1/"`
 dirs_list=`ls | grep $DIR_PATTERN | sort`
 free_pre=$free_k
 [ $free_pre -lt $reserve_k ] ; }
 do
 dir_oldest=`echo $dirs_list | tr " " "\n" | head -1`
 [ -d $dir_oldest ] && { logger -t BACKUP -p $BACKUP_LOG_FACILITY "Deleting old backup in $BACKUP_MAIN_DIR/$dir_oldest" ; rm -rf $dir_oldest; }
 done
 fi
 [ "$VERIFY_BACKUP_MOUNTED" = "yes" ] && verify_backup_mounted
 last_date=`ls | grep $DIR_PATTERN | sort | tail -1`
 if [ -n "$last_date" -a \( "$CURR_DATE" != "$last_date" \) ]
 then
 logger -t BACKUP -p $BACKUP_LOG_FACILITY "Preparing. Copying $BACKUP_MAIN_DIR/$last_date -> $BACKUP_MAIN_DIR/$CURR_DATE"
 mkdir $CURR_DATE 1>/dev/null 2>/dev/null
 cp -al "$last_date"/* $CURR_DATE 1>/dev/null 2>/dev/null
 rm -rf $CURR_DATE/_delta 1>/dev/null 2>/dev/null
 fi
 mkdir $CURR_DATE/_delta 1>/dev/null 2>/dev/null
 if [ $BACKUP_EXPIRES_DAYS -gt 0 ]
 then
 for expired_dir in `find "$BACKUP_MAIN_DIR" -maxdepth 1 -mtime +$BACKUP_EXPIRES_DAYS -type d | grep "$DIR_PATTERN"`
 do
 logger -t BACKUP -p $BACKUP_LOG_FACILITY "Deleting expired backup $expired_dir" ; rm -rf $expired_dir;
 done
 fi
 cd $old_dir
 return 0
}
make_backup() {
 while [ -n "$1" ]
 do
 [ "$VERIFY_BACKUP_MOUNTED" = "yes" ] && verify_backup_mounted
 src=$1
 full_src=`echo $PWD/$1 | sed -e 's://:/:g'`
 dst=`echo $BACKUP_MAIN_DIR/$CURR_DATE/$src | sed -e "s/\/\w\+$//"`
 mkdir -p $dst 1>/dev/null 2>/dev/null
 logger -t BACKUP -p $BACKUP_LOG_FACILITY "$full_src started"
 rsync -axW8 --del --exclude-from=/etc/default/backup_exclude $src $dst 2>>$BACKUP_ERRORS
 sync
 shift
 done
 return 0
}
make_backup_with_delta() {
 while [ -n "$1" ]
 do
 [ "$VERIFY_BACKUP_MOUNTED" = "yes" ] && verify_backup_mounted
 src=$1
 full_src=`echo $PWD/$1 | sed -e 's://:/:g'`
 dst=`echo $BACKUP_MAIN_DIR/$CURR_DATE/$src | sed -e "s/\/\w\+$//"`
 mkdir -p $dst 1>/dev/null 2>/dev/null
 rm $BACKUP_DELTA 1>/dev/null 2>/dev/null
 logger -t BACKUP -p $BACKUP_LOG_FACILITY "$full_src (with delta) started"
 rsync -axW8i --del $src $dst --exclude-from=/etc/default/backup_exclude 2>>$BACKUP_ERRORS | grep "^>f" | cut -d ' ' -f 2- 1>$BACKUP_DELTA
 old_dir=`pwd`
 cd $BACKUP_MAIN_DIR/$CURR_DATE
 dst=`echo $src | sed -e "s/\w\+$//"`
 xargs -a $BACKUP_DELTA -r -n5 -d '\n' -I '{}' echo $dst{} | xargs -r -n10 -d '\n' cp -ul --parents -t _delta
 rm $BACKUP_DELTA 1>/dev/null 2>/dev/null
 cd $old_dir
 sync
 shift
 done
 return 0
}
send_email_report() {
 if [ -s $BACKUP_ERRORS ]
 then
 logger -t BACKUP -p $BACKUP_LOG_FACILITY "Sending email report"
 echo 'Content-type: text/plain; charset=utf-8' >> $BACKUP_REPORT
 echo 'Content-Transfer-Encoding: 8bit' >> $BACKUP_REPORT
 echo 'From: [email protected]'`hostname --fqdn` >> $BACKUP_REPORT
 echo 'To: root' >> $BACKUP_REPORT
 echo 'Date:' `date` >> $BACKUP_REPORT
 echo -e 'Subject: Cron <[email protected]'`hostname --fqdn`'> BACKUP\n\n' >> $BACKUP_REPORT
 cat $BACKUP_ERRORS >> $BACKUP_REPORT
 cat $BACKUP_REPORT | sendmail root
 fi
 rm $BACKUP_DELTA $BACKUP_ERRORS $BACKUP_REPORT $PID_FILE 1>/dev/null 2>/dev/null
 logger -t BACKUP -p $BACKUP_LOG_FACILITY "Finished"
 return 0
}
make_mysql_backup() {
 MYSQL_DATA_DIR='/var/lib/mysql'
 mkdir $BACKUP_MAIN_DIR/$CURR_DATE/MySQL 1>/dev/null 2>/dev/null
 rm -rf $BACKUP_MAIN_DIR/$CURR_DATE/MySQL/* 1>/dev/null 2>/dev/null
 rm -rf $BACKUP_MYSQL_DIR 1>/dev/null 2>/dev/null
 mkdir -p $BACKUP_MYSQL_DIR 1>/dev/null 2>/dev/null
 cd $MYSQL_DATA_DIR
 logger -t BACKUP -p $BACKUP_LOG_FACILITY "MySQL started"
 for db_dir in `ls -p | grep '/' | tr -d '/'`
 do
 cd $MYSQL_DATA_DIR/$db_dir
 db_name=`echo $db_dir | sed -e 's/@003d/=/g' -e 's/@002d/-/g'`
 logger -t BACKUP -p $BACKUP_LOG_FACILITY "MySQL database '$db_name' started"
 for table in `ls | grep '.frm' | sed -e 's/\.frm//' -e 's/ /:::/g'`
 do
 table=`echo $table | sed -e 's/:::/ /g' -e 's/@003d/=/g' -e 's/@002d/-/g'`
 mysqldump $db_name "$table" --skip-lock-tables -Q -u $mysql_user -p$mysql_pass > "$BACKUP_MYSQL_DIR/$table.sql"
 done
 cd $BACKUP_MYSQL_DIR
 tar czf $BACKUP_MAIN_DIR/$CURR_DATE/MySQL/$db_name.tar.gz * 1>/dev/null 2>/dev/null
 rm $BACKUP_MYSQL_DIR/* 1>/dev/null 2>/dev/null
 done
 return 0
}