How to uncompress zlib data in UNIX?

I have created zlib-compressed data in Python, like this: import zlib s = '...' z = zlib.compress(s) with open('/tmp/data', 'w') as f: f.write(z) (or one-liner in shell: echo -n '...' | python2 -c 'import sys,zlib; sys.stdout.write(zlib.compress(sys.stdin.read()))' > /tmp/data) Now, I want to uncompress the data in shell. Neither zcat nor uncompress work: $ cat /tmp/data | gzip -d - gzip: stdin: n