Tape backup script with % capacity tracking per-tape (across sessions)

tape-arc-progress.sh

#!/bin/sh       
                                       
die() {           
        echo $@
        exit 1                       
}                 
                                       
which bc || die "no bc found"

if [ $# -lt 2 ] ; then              
        echo "$0 directory_to_archive logfile"
        exit 1
fi
                                                                              
date      

                                       
tapedensity=$(mt-st -f /dev/nst0 status | grep Density | grep -o -e LTO-.)                                                                                  
                                                                              
case $tapedensity in                                                          
        "LTO-2")
                tapesize="200*1024^3"
                ;;
        "LTO-3")                                                                                                                                            
                tapesize="400*1024^3"
                ;;          
        *)                         
                tapesize="200*1024^3"
                ;;                                                            
esac                                                                          
                                       
                                                                              
tapesize=$(echo "$tapesize" | bc -l)                                          
                                       

                                                                              
size=$(du -sb "$1" | awk '{ print $1}') 
logfile=$2
                                       
if [ ! -e "$logfile" ] ; then 
        echo "========================================================================" >> $logfile
        echo "Tape size : $tapesize" > $logfile
        echo "first record on this tape"
        record=0            
        lastwrite=0                                                           
else
        echo "========================================================================" >> $logfile
        text=$(grep asf $logfile)
        echo "${text##*asf}"                                                  
        record=$(grep asf $logfile)
        record=${record##*asf}                                                
        # find out current record from txt file
        echo "starting with record $record"
        record=$((record+1))                                                  
        lastwrite=$(grep "written" $logfile)
        lastwrite=${lastwrite##*written}                      
fi                                                                            

echo "mt-st -f /dev/nst0 asf ${record}" >> $logfile  


echo "files : " >> $logfile
find "$1" -type f >> $logfile
echo "Total size : $size bytes" >> $logfile
du -hs "$1" >> $logfile

echo "Data to write : $size"
size_gb=$(echo "scale=2; $size / 1024 / 1024 / 1024" | bc -l)

echo "That is $size_gb GB"

tar cf - "$1" | pv -s ${size} > /dev/nst0

written=$(echo "$size+$lastwrite" | bc -l)

echo "written $written" >> $logfile
capacity=$(echo "scale=4; $written/$tapesize*100" | bc -l)

written_gb=$(echo "scale=2; $written /1024/1024/1024" | bc -l)
tapesize_gb=$(echo "scale=2; $tapesize /1024/1024/1024" | bc -l)

echo "that is $capacity % of the tape so far" | tee -a $logfile
echo "$written_gb / $tapesize_gb (GB)"