Simple test to check the usage of dd command. This script allows to split a file into chunks and merge them back from chunks to original file using dd command in linux. https://labbots.com/split-and-merge-file-using-dd-command/

split_merge_file.sh

#!/bin/bash
#!/bin/bashset -e

PROGNAME=${0##*/}
SHORTOPTS="mbs:d:p:" 
LONGOPTS="merge,split,source:,destination:,prefix:" 
set -o errexit -o noclobber -o pipefail

OPTS=$(getopt -s bash --options $SHORTOPTS --longoptions $LONGOPTS --name $PROGNAME -- "$@" )
eval set -- "$OPTS"
#Base variable declaration
FILE=""
DESTINATION=""
MERGE=false
SPLIT=false
PREFIX="split"
BLOCK_SIZE=10000

while true; do
  case "$1" in
  	-m | --merge ) MERGE=true; shift ;;
    -b | --split ) SPLIT=true; shift ;;
    -s | --source ) FILE="$2"; shift 2 ;;
    -d | --destination ) DESTINATION="$2"; shift 2 ;;
	-p | --prefix ) PREFIX="$2"; shift 2 ;;
    -- ) shift; break ;;
    * )  break ;;
  esac
done


# if both merge and split flags are set then throw error
if [ "$MERGE" = true ] && [ "$SPLIT" = true ]; then
		echo "Cannot set flag merge and split at the same time."
		exit 1
fi

# if no flags are set then throw error
if [ "$MERGE" = false ] && [ "$SPLIT" = false ]; then
		echo "Atlest one of the merge or split flag must be set."
		exit 1
fi

# If Destination folder is specified then we check whether the folder is there, if not the folder is created.
if [ ! -z "$DESTINATION" ] && [ ! -d "$DESTINATION" ];then
	mkdir -p $DESTINATION
	if [ $? -ne 0 ];then
    	echo "Creating destination directory failed."
    	exit 1
	fi
	DESTINATION="$(readlink -f $DESTINATION)"

fi

if [ ! -z "$DESTINATION" ] && [ -d "$DESTINATION" ];then
	
	DESTINATION="$(readlink -f $DESTINATION)"
fi

# If Destination is empty then create files in the same directory as of source file
if [ -z "$DESTINATION" ];then
	
	DESTINATION="$(dirname "$(readlink -f $FILE)")"
fi

if [ ! -z "$1" ];then
	FILE="$1"
fi


if [ ! -z "$SPLIT" ] && [ "$SPLIT" = true ];then
	
	if [ ! -f "$FILE" ];then
		echo "Invalid file name : $FILE"
			exit 1
	fi

	FULLFILENAME=$(basename $FILE)
	FILENAME="${FULLFILENAME%.*}"
	FILESIZE=$(stat -c%s "$FILE")


	BLOCKS=$(((FILESIZE + (BLOCK_SIZE + 1)) / BLOCK_SIZE))

	echo "$FILESIZE"
	echo "$BLOCKS"

	for (( block = 0; block < $BLOCKS; block += 1 ))
	do 
	    echo $block;
	    START_RANGE=$((block*BLOCK_SIZE))
	    END_RANGE=$((((block +1) * BLOCK_SIZE) - 1))
	    if [ "$block" -eq  $((BLOCKS-1)) ]
	    	then
	    	END_RANGE=$FILESIZE
	    fi
	    echo "$START_RANGE : $END_RANGE"
	    dd if=$FILE skip=$block bs=$BLOCK_SIZE count=1  status=noxfer 2> /dev/null  > "${DESTINATION}/${PREFIX}|${FILENAME}|${block}"
	done
fi

if [ ! -z "$MERGE" ] && [ "$MERGE" = true ];then

	if [ ! -d "$FILE" ];then
		echo "Invalid source folder : $FILE"
		exit 1
	fi
  	FILENAME=$(find -name "split|*" | sort -V | head -1 | sed -n  "s/.*split|\([a-zA-Z0-9_\-]*\)|[0-9]*/\1/p")
  	#cat $(find $FILE -name "${PREFIX}|*" | sort -V) > "${DESTINATION}/${FILENAME}"

  	FILES=$(find -name "split|*"  | sort -V | sed ':a;N;$!ba;s/\n/ /g')
  	for f in $FILES 
	do
		dd if=$f of=${DESTINATION}/${FILENAME} conv=notrunc oflag=append bs=$BLOCK_SIZE	
	done
fi