(gzip.info) Invoking gzip
(gzip.info) Advanced usage
The format for running the `gzip' program is:
gzip OPTION ...
`gzip' supports the following options:
Write output on standard output; keep original files unchanged.
If there are several input files, the output consists of a
sequence of independently compressed members. To obtain better
compression, concatenate all input files before compressing them.
Force compression or decompression even if the file has multiple
links or the corresponding file already exists, or if the
compressed data is read from or written to a terminal. If the
input data is not in a format recognized by `gzip', and if the
option `--stdout' is also given, copy the input data without
change to the standard output: let `zcat' behave as `cat'. If `-f'
is not given, and when not running in the background, `gzip'
prompts to verify whether an existing file should be overwritten.
Print an informative help message describing the options then quit.
For each compressed file, list the following fields:
compressed size: size of the compressed file
uncompressed size: size of the uncompressed file
ratio: compression ratio (0.0% if unknown)
uncompressed_name: name of the uncompressed file
The uncompressed size is given as `-1' for files not in `gzip'
format, such as compressed `.Z' files. To get the uncompressed
size for such a file, you can use:
zcat file.Z | wc -c
In combination with the `--verbose' option, the following fields
are also displayed:
method: compression method (deflate,compress,lzh,pack)
crc: the 32-bit CRC of the uncompressed data
date & time: time stamp for the uncompressed file
The crc is given as ffffffff for a file not in gzip format.
With `--verbose', the size totals and compression ratio for all
files is also displayed, unless some sizes are unknown. With
`--quiet', the title and totals lines are not displayed.
The `gzip' format represents the the input size modulo 2^32, so
the uncompressed size and compression ratio are listed incorrectly
for uncompressed files 4 GB and larger. To work around this
problem, you can use the following command to discover a large
uncompressed file's true size:
zcat file.gz | wc -c
Display the `gzip' license then quit.
When compressing, do not save the original file name and time
stamp by default. (The original name is always saved if the name
had to be truncated.) When decompressing, do not restore the
original file name if present (remove only the `gzip' suffix from
the compressed file name) and do not restore the original time
stamp if present (copy it from the compressed file). This option
is the default when decompressing.
When compressing, always save the original file name and time
stamp; this is the default. When decompressing, restore the
original file name and time stamp if present. This option is
useful on systems which have a limit on file name length or when
the time stamp has been lost after a file transfer.
Suppress all warning messages.
Travel the directory structure recursively. If any of the file
names specified on the command line are directories, `gzip' will
descend into the directory and compress all the files it finds
there (or decompress them in the case of `gunzip').
Use suffix `SUF' instead of `.gz'. Any suffix can be given, but
suffixes other than `.z' and `.gz' should be avoided to avoid
confusion when files are transferred to other systems. A null
suffix forces gunzip to try decompression on all given files
regardless of suffix, as in:
gunzip -S "" * (*.* for MSDOS)
Previous versions of gzip used the `.z' suffix. This was changed to
avoid a conflict with `pack'.
Test. Check the compressed file integrity.
Verbose. Display the name and percentage reduction for each file
Version. Display the version number and compilation options, then
Regulate the speed of compression using the specified digit N,
where `-1' or `--fast' indicates the fastest compression method
(less compression) and `--best' or `-9' indicates the slowest
compression method (optimal compression). The default compression
level is `-6' (that is, biased towards high compression at expense
(gzip.info) Advanced usage
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