Hi.
I did not need to unzip twice. Perhaps this will help explain the difference in lengths:
#!/usr/bin/env bash
# @(#) s1 Demonstrate gzip lengths.
# Utility functions: print-as-echo, print-line-with-visual-space, debug.
pe() { for i;do printf "%s" "$i";done; printf "\n"; }
pl() { pe;pe "-----" ;pe "$*"; }
db() { ( printf " db, ";for i;do printf "%s" "$i";done; printf "\n" ) >&2 ; }
db() { : ; }
C=$HOME/bin/context && [ -f $C ] && $C spit gzip
rm -f f1 f1.gz f2 f2.gz f3 f3.gz f4 f4.gz f5 f5.gz
spit -c 10 -r 5 > f1
cp f1 f2
cp f1 f3
pl " Input data files f1, f2:"
wc f1 f2
pl " Results, re-direction:"
cat f1 | gzip > f1.gz
wc f1.gz
rm -f f1
pl " Results, by filename:"
gzip -n f2
wc f2.gz
pl " Results, by filename, plain:"
gzip f3
wc f3.gz
cp f1.gz f4.gz
cp f3.gz f5.gz
pl " All files compressed, contents:"
ls -lgG f*
pe
file f*
pl " All files uncompressed:"
for f in *.gz
do
gunzip $f
done
ls -lgG f*
exit 0
producing:
% ./s1
Environment: LC_ALL = C, LANG = C
(Versions displayed with local utility "version")
OS, ker|rel, machine: Linux, 2.6.26-2-amd64, x86_64
Distribution : Debian GNU/Linux 5.0.8 (lenny)
GNU bash 3.2.39
spit - ( local: RepRev 1.3, ~/bin/spit, 2011-04-29 )
gzip 1.3.12
-----
Input data files f1, f2:
5 50 100 f1
5 50 100 f2
10 100 200 total
-----
Results, re-direction:
0 1 30 f1.gz
-----
Results, by filename:
0 1 30 f2.gz
-----
Results, by filename, plain:
0 1 33 f3.gz
-----
All files compressed, contents:
-rw-r--r-- 1 30 Jun 3 21:45 f1.gz
-rw-r--r-- 1 30 Jun 3 21:45 f2.gz
-rw-r--r-- 1 33 Jun 3 21:45 f3.gz
-rw-r--r-- 1 30 Jun 3 21:45 f4.gz
-rw-r--r-- 1 33 Jun 3 21:45 f5.gz
f1.gz: gzip compressed data, from Unix, last modified: Fri Jun 3 21:45:43 2011
f2.gz: gzip compressed data, from Unix
f3.gz: gzip compressed data, was "f3", from Unix, last modified: Fri Jun 3 21:45:43 2011
f4.gz: gzip compressed data, from Unix, last modified: Fri Jun 3 21:45:43 2011
f5.gz: gzip compressed data, was "f3", from Unix, last modified: Fri Jun 3 21:45:43 2011
-----
All files uncompressed:
-rw-r--r-- 1 100 Jun 3 21:45 f1
-rw-r--r-- 1 100 Jun 3 21:45 f2
-rw-r--r-- 1 100 Jun 3 21:45 f3
-rw-r--r-- 1 100 Jun 3 21:45 f4
-rw-r--r-- 1 100 Jun 3 21:45 f5
See man gzip for details.
Best wishes ... cheers, drl