gzip, gunzip,
  zcat —
compression/decompression tool using Lempel-Ziv coding
  (LZ77)
  
    | gzip | [ -cdfhlNnqrtVv] [-Ssuffix] file
      [file [...]] | 
  
    | gunzip | [ -cfhNqrtVv] [-Ssuffix] file
      [file [...]] | 
  
    | zcat | [ -fhV] file
      [file [...]] | 
The gzip program compresses and decompresses files using
  Lempel-Ziv coding (LZ77). If no files are specified,
  gzip will compress from standard input, or decompress
  to standard output. When in compression mode, each file
  will be replaced with another file with the suffix, set by the
  -S suffix option, added, if
  possible. In decompression mode, each file will be
  checked for existence, as will the file with the suffix added.
If invoked as gunzip then the
    -d option is enabled. If invoked as
    zcat or gzcat then both the
    -c and -d options are
    enabled.
This version of gzip is also capable of
    decompressing files compressed using
    compress(1),
    bzip2(1),
    lzip, or
    xz(1).
The following options are available:
  - -1,- -- -fast
-  
- -2
-  
- -3
-  
- -4
-  
- -5
-  
- -6
-  
- -7
-  
- -8
-  
- -9,- -- -best
- These options change the compression level used, with the
      -1option being the fastest, with less
      compression, and the-9option being the slowest,
      with optimal compression. The default compression level is 6.
- -c,- -- -stdout,- -- -to-stdout
- This option specifies that output will go to the standard output stream,
      leaving files intact.
- -d,- -- -decompress,- -- -uncompress
- This option selects decompression rather than compression.
- -f,- -- -force
- This option turns on force mode. This allows files with multiple links,
      overwriting of pre-existing files, reading from or writing to a terminal,
      and when combined with the -coption, allowing
      non-compressed data to pass through unchanged.
- -h,- -- -help
- This option prints a usage summary and exits.
- -k,- -- -keep
- This option prevents gzipfrom deleting input
      files after (de)compression.
- -l,- -- -list
- This option displays information about the file's compressed and
      uncompressed size, ratio, uncompressed name. With the
      -voption, it also displays the compression
      method, CRC, date and time embedded in the file.
- -N,- -- -name
- This option causes the stored filename in the input file to be used as the
      output file.
- -n,- -- -no-name
- This option stops the filename and timestamp from being stored in the
      output file.
- -q,- -- -quiet
- With this option, no warnings or errors are printed.
- -r,- -- -recursive
- This option is used to gzipthe files in a
      directory tree individually, using the
      fts(3) library.
- -Ssuffix,- -- -suffixsuffix
- This option changes the default suffix from .gz to
      suffix.
- -t,- -- -test
- This option will test compressed files for integrity.
- -V,- -- -version
- This option prints the version of the gzipprogram.
- -v,- -- -verbose
- This option turns on verbose mode, which prints the compression ratio for
      each file compressed.
If the environment variableGZIP is set, it is parsed as
  a white-space separated list of options handled before any options on the
  command line. Options on the command line will override anything in
  GZIP.
The gzip utility exits 0 on success, 1 on errors, and 2
  if a warning occurs.
gzip responds to the following signals:
  - SIGINFO
- Report progress to standard error.
Thegzip program was originally written by Jean-loup
  Gailly, licensed under the GNU Public Licence. Matthew R. Green wrote a simple
  front end for NetBSD 1.3 distribution media, based on
  the freely re-distributable zlib library. It was enhanced to be mostly
  feature-compatible with the original GNU gzip program
  for NetBSD 2.0.
This manual documents NetBSD
    gzip version 20170803.