Split a large .gz file and gzip each of split file?
Solution 1:
Here's a loop around awk
and gzip
that will split a file on line boundaries and compress the parts as it goes:
# Generate files part0.dat.gz, part1.dat.gz, etc.
prefix="part"
count=0
suffix=".dat"
lines=10000 # Split every 10000 line.
zcat thefile.dat.gz |
while true; do
partname=${prefix}${count}${suffix}
# Use awk to read the required number of lines from the input stream.
awk -v lines=${lines} 'NR <= lines {print} NR == lines {exit}' >${partname}
if [[ -s ${partname} ]]; then
# Compress this part file.
gzip --best ${partname}
(( ++count ))
else
# Last file generated is empty, delete it.
rm -f ${partname}
break
fi
done
To recreate the original file, just zcat part*.dat.gz | gzip --best >thefile1.dat.gz
. The compressed file might have a different MD5 checksum from the original due to varying gzip
compression options used, but the uncompressed files will be absolutely identical.