Simple bash hash verification utility

hashchecker

#!/bin/bash
# hashchecker Created by Tugzrida(https://gist.github.com/Tugzrida)
# A simple utility that accepts a file path and expected md5, sha1 or
# sha256 hash, then verifies the file matches the expected hash.

# Hash length assumptions:
# md5 - 32 chars
# sha1 - 40 chars
# sha256 - 64 chars

file_to_verify="$1"
expected_hash="$2"
length=${#expected_hash}
case "$length" in
  32)
    md5=true
    ;;
  40)
    sha1=true
    ;;
  64)
    sha256=true
    ;;
  128)
    sha512=true
    ;;
  *)
    echo "Usage: $(basename $0) file_to_verify expected_hash"
    exit 1
  ;;
esac

function abspath()
{
  case "${1}" in
    [./]*)
    echo "$(cd ${1%/*}; pwd)/${1##*/}"
    ;;
    *)
    echo "${PWD}/${1}"
    ;;
  esac
}

echo "Checking hash for $(abspath $file_to_verify)"

if [ $md5 ]; then
    echo "Presuming md5 hash. Calculating..."
    command -v md5sum >/dev/null && calculated_hash=$(md5sum "$file_to_verify" | awk '{print $1}') || calculated_hash=$(md5 "$file_to_verify" | awk '{print $NF}')
fi

if [ $sha1 ]; then
    echo "Presuming sha1 hash. Calculating..."
    calculated_hash=$(shasum -a 1 "$file_to_verify" | awk '{print $1}')
fi

if [ $sha256 ]; then
    echo "Presuming sha256 hash. Calculating..."
    calculated_hash=$(shasum -a 256 "$file_to_verify" | awk '{print $1}')
fi

if [ $sha512 ]; then
    echo "Presuming sha512 hash. Calculating..."
    calculated_hash=$(shasum -a 512 "$file_to_verify" | awk '{print $1}')
fi

echo "Provided hash:   $expected_hash"
echo "Calculated hash: $calculated_hash"
if [ "$calculated_hash" == "$expected_hash" ]; then
    printf "\e[92mHashes match\e[39m\n"
    exit 0
fi
printf "\e[91mHashes don't match!\e[39m\n"
exit 1