解决：gzip -c test.txt >/root/test.gz，文件流重定向，解压也是，gunzip -c /root/test.gz >./test.txt
经验：更常用的命令tar同样可以解压*.gz，参数为-c
附gzip帮助文件
GZIP(1) General Commands Manual GZIP(1)
NAME
gzip, gunzip, zcat - compress or expand files
SYNOPSIS
gzip [ -acdfhlLnNrtvV19 ] [-S suffix] [ name ... ]
gunzip [ -acfhlLnNrtvV ] [-S suffix] [ name ... ]
zcat [ -fhLV ] [ name ... ]
OPTIONS
-a --ascii
Ascii text mode: convert end-of-lines using local conventions.
This option is supported only on some non-Unix systems. For
MSDOS, CR LF is converted to LF when compressing, and LF is con‐
verted to CR LF when decompressing.
-c --stdout --to-stdout
Write output on standard outputkeep 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.
-d --decompress --uncompress
Decompress.
-f --force
Force compression or decompression even if the file has multiple
links or the corresponding file already exists, or if the com‐
pressed 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.
-h --help
Display a help screen and quit.
-l --list
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 for‐
mat, 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
crc: the 32-bit CRC of the uncompressed data
date &time: time stamp for the uncompressed file
The compression methods currently supported are deflate, com‐
press, lzh (SCO compress -H) and pack. The crc is given as
ffffffff for a file not in gzip format.
With --name, the uncompressed name, date and time are those
stored within the compress file if present.
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.
-L --license
Display the gzip license and quit.
-n --no-name
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.
-N --name
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.
-q --quiet
Suppress all warnings.
-r --recursive
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 ).
-S .suf --suffix .suf
When compressing, use suffix .suf instead of .gz. Any non-empty
suffix can be given, but suffixes other than .z and .gz should
be avoided to avoid confusion when files are transferred to
other systems.
When decompressing, add .suf to the beginning of the list of
suffixes to try, when deriving an output file name from an input
file name.
pack(1).
-t --test
Test. Check the compressed file integrity.
-v --verbose
Verbose. Display the name and percentage reduction for each file
compressed or decompressed.
-V --version
Version. Display the version number and compilation options then
quit.
-# --fast --best
Regulate the speed of compression using the specified digit #,
where -1 or --fast indicates the fastest compression method
(less compression) and -9 or --best indicates the slowest com‐
pression method (best compression). The default compression
level is -6 (that is, biased towards high compression at expense
of speed).
引用：如果有使用Zip.DecompressFile()方法去解压标准的ZIP文件，就会出现以下错误：
GZip 头中的幻数不正确。请确保正在传入 GZip 流。
此外，使用Zip.CompressFile()方法也不能将多个文件放入一个ZIP包。
看来，FCL2.0还是不能处理标准的ZIP文件，我目前是使用第三方的ICSharpZipLib来处理ZIP文件
似乎发现都是用第三方的库比较多
GZIP格式说明
http://hi.baidu.com/skyyzq/blog/item/366ecc1f66785f0b314e156f.html
