GZip

It's impossible to know the uncompressed size without read all data.

gzip is file format used to compress. It use deflate compression algorithm

gzip is GZIP headers, DEFLATE data (compressed data), and a checksum

zlib is the most common library to handle gzip file format

Compress gzip without save filename and timestamp gzip -9 -n -k -f file

• Zopfli (see also the Thread about it on encode.su)

• DeflOpt (Win, Unix?) support GZIP, PNG and ZIP files (see also the Thread about it on encode.su)

• Defluff

• ScriptGZIP (Win CMD)

• gzthermal use to view compression efficiency (see also the Thread about it on encode.su)

• deflate-analyzer - same as gzthermal but online

• zlib Technical Details

Resources

• Gzip - ForensicsWiki

• gzthermal: pseudo thermal view of Gzip/Deflate compression efficiency

• Huffmix: a PNGOUT -r catalyst

• defdb a tool to dump the deflate stream from .gz and .png files

• SharpZipLib/src/ICSharpCode.SharpZipLib/GZip at master · icsharpcode/SharpZipLib

Concatenation

You can concatenate/merge multiple gzip in one gzip:

echo 1 > 1.txt ; echo 2 > 2.txt; echo 3 > 3.txt;
gzip 1; gzip 2; gzip 3;
cat 1.gz 2.gz 3.gz > all.gz

gunzip -c all.gz > all.txt

cat all.txt
# will output:
1
2
3

The same as cat 1.txt 2.txt 3.txt

Can be usefull when you want add a small data before or after a big chunk already compressed

• GNU Gzip

• https://tools.ietf.org/html/rfc1952#page-5

• Is there a GZIP merger that merges two GZIP files without decompressing them? - Stack Overflow