rand-file

#!/bin/bash
## $PROG 1.0.0 - Generate randoms files and checks their integrity
## 
## Usage: $PROG [OPTION...] [COMMAND]...
## Options:
##   -s, --size SIZE=4K                 Size (numfmt iec accepted: 1K, 1M, 1G...) of random bytes per file. 
##   -n, --number NUMBER=1              Number of files to generate
##   -c, --checksum CHECKSUM=sha1sum    Checksum function to verify the files. Use none for no verification.
## Commands:
##   -h, --help                         Displays this help and exists
##   -v, --version                      Displays output version and exists
##   -d, --delete                       Clears all the generated files
## Examples:
##   $PROG -s 1G -n 5 -c sha512sum
##   $PROG -s 1G -n 5 -c none
SCRIPT_DIR="$(dirname "$0")"
PROG=${0##*/}

set -o errexit

# Configs
size=4K
count=1
checksum=sha1sum

# Commands
help() 
{
    grep "^##" "$0" | sed -e "s/^...//" -e "s/\$PROG/$PROG/g"
    exit 0
}

version() 
{
    help | head -1
    exit 0
}

delete()
{
    rm ./random-*.bin
    rm ./checksums-*.txt
    exit 0
}

# Helper functions
echoerr() 
{ 
    echo "$@" 1>&2 
}

repl() 
{
     printf "$1"'%.s' $(eval "echo {1.."$(($2))"}")
} 

clearLine() 
{
    printf "\r"
    repl " " $1
    printf "\r"
}

clearPrintLast=""

clearPrint()
{
    clearLine ${#clearPrintLast}
    clearPrintLast="$@"
    printf "$@"
}

none()
{
    :
}

# Args Config functions
size()
{
    size=$1
    return 1
}

number()
{
    if test -z $1; then
        count=1
    elif test $1 -lt 1; then
        echoerr "Count argument must be more than 1"
        exit 1
    fi

    count=$1
    return 1
}

checksum()
{
    checksum=$1
    return 1
}

# Parsing CLI Args
[ $# = 0 ] && help
while [ $# -gt 0 ]; do
  CMD=$(grep -m 1 -Po "^## *$1, --\K[^= ]*|^##.* --\K${1#--}(?:[= ])" ${SCRIPT_DIR}/${PROG} | sed -e "s/-/_/g")
  if [ -z "$CMD" ]; then echo "ERROR: Command '$1' not supported"; exit 1; fi
  shift; eval "$CMD" $@ || shift $? 2> /dev/null
done

# Entry
basename=random-$size-

size=$(numfmt --from=iec $size)
checksumFile="checksums-${checksum}.txt"

printf "" > ${checksumFile}

for i in $(seq 1 $count); do
    file=${basename}${i}.bin

    clearPrint "Generating ${file}"

    head -c ${size} /dev/urandom > ${file}
    
    clearPrint "Checking ${file}"
    
    fileSize=$(stat --printf="%s" ${file})

    if test $fileSize -ne $size; then
        echoerr "File size miss match. Target: ${size} Actual: ${fileSize}"
        exit 1
    fi

    $checksum ${file} >> ${checksumFile}

    clearPrint "Done ${file}\n"
done

if test "$checksum" = "none"; then
    rm ${checksumFile}
    exit
fi

echo "Verifying files"

$checksum -c ${checksumFile}