Thomas Weise (汤卫思)

A professor at Hefei University.

2 minute read

In this recent post, I gave a small script for packing files and folders into tar.xz archives. To the best of my knowledge, this offers the best compression ratio. However, sadly, not everybody knows how to deal with tar.xz archives and there might be situations where we must provide data as zip archives. These usually have a much worse compression ratio, but are fast to compress and uncompress and widely accepted. I here present the small / script zipCompress.sh, which is drop-in compatible with xzCompress.sh but instead produces zip archives. It attempts to produce the strongest zip compression possible with the built-in tools. You can download the script from here.

If you want to compress a single file or folder named X, just invoke zipCompress.sh "X" and this will create the archive X.zip. If you want to store multiple files or folders, say, A, B, and C, into an archive named Y.zip, then you would write zipCompress.sh "Y" "A" "B" "C".

The resulting archives Z.zip can later be unpacked using unzip Z.zip.

#!/bin/bash

# Compress files and folders to .zip archives, using the strongest
# available zip compression.
# This compression is generally worse than tar.xz compression.
# Later, you can decompress the generated archive with the command
# "unzip archive.zip".
#
# The script can be called in two ways:
#
# 1. With a single parameter 'X', which can be either a file or directory.
#    Then, an archive with name 'X.zip' is created and the contents of 'X'
#    are packaged into it.
#
# 2. With multiple parameters 'Y', 'A', 'B', 'C', and so on.
#    Then, an archive with name 'Y.zip' is created and the contents of 'A',
#    'B', and 'C', and so on are packaged into it.
#    'Y' is treated solely as archive name, not as source.

# strict error handling
set -o pipefail  # trace ERR through pipes
set -o errtrace  # trace ERR through 'time command' and other functions
set -o nounset   # set -u : exit the script if you try to use an uninitialized variable
set -o errexit   # set -e : exit the script if any statement returns a non-true return value

dest="${1%/}"
dest="$(basename "$dest").zip"
echo "$(date +'%0Y-%0m-%0d %0R:%0S'): Destination archive name is '$dest'."

if [ $# \> 1 ];
then
    echo "$(date +'%0Y-%0m-%0d %0R:%0S'): Beginning to compress sources '${@:2}' to destination '$dest'"
    nice -n 19 zip -9 -r "$dest" "${@:2}"
else
    echo "$(date +'%0Y-%0m-%0d %0R:%0S'): Beginning to compress sources '$1' to destination '$dest'"
    nice -n 19 zip -9 -r "$dest" "$1"
fi

echo "$(date +'%0Y-%0m-%0d %0R:%0S'): Done compressing to destination '$dest'."

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