zip.1

给出了 zip 压缩算法的完整实现过程。

.\" =========================================================================
.\" Copyright (c) 1990-2006 Info-ZIP.  All rights reserved.
.\"
.\" See the accompanying file LICENSE, version 2005-Feb-10 or later
.\" (the contents of which are also included in zip.h) for terms of use.
.\" If, for some reason, all these files are missing, the Info-ZIP license
.\" also may be found at:  ftp://ftp.info-zip.org/pub/infozip/license.html
.\" ==========================================================================
.\"
.\" zip.1 by Mark Adler, Jean-loup Gailly and R. P. C. Rodgers
.\"
.TH ZIP 1L "19 June 2006 (v2.32)" Info-ZIP
.SH NAME
zip, zipcloak, zipnote, zipsplit \- package and compress (archive) files
.SH SYNOPSIS
.B zip
.RB [ \-aABcdDeEfFghjklLmoqrRSTuvVwXyz!@$ ]
.RB [ \-b\ path ]
.RB [ \-n\ suffixes ]
.RB [ \-t\ mmddyyyy ]
.RB [ \-tt\ mmddyyyy ]
.I [ zipfile
.I [ file1
.IR file2 " .\|.\|." ]]
.RB [ \-xi\ list ]
.PP
.B zipcloak
.RB [ \-dhL ]
.RB [ \-b\ path ]
.I zipfile
.PP
.B zipnote
.RB [ \-hwL ]
.RB [ \-b\ path ]
.I zipfile
.PP
.B zipsplit
.RB [ \-hiLpst ]
.RB [ \-n\ size ]
.RB [ \-b\ path ]
.I zipfile
.SH DESCRIPTION
.I zip
is a compression and file packaging utility for Unix, VMS, MSDOS,
OS/2, Windows NT, Minix, Atari and Macintosh, Amiga and Acorn RISC OS.
.LP
It is analogous to a combination of the UNIX commands
.IR tar (1)
and
.IR compress (1)
and is compatible with PKZIP (Phil Katz's ZIP for MSDOS systems).
.LP
A companion program
.RI ( unzip (1L)),
unpacks
.I zip
archives.
The
.I zip
and
.IR unzip (1L)
programs can work with archives produced by PKZIP,
and PKZIP and PKUNZIP can work with archives produced by
.IR zip .
.I zip
version 2.32 is compatible with PKZIP 2.04.
Note that PKUNZIP 1.10 cannot extract files produced by PKZIP 2.04
or
.I zip
2.32. You must use PKUNZIP 2.04g or
.I unzip
5.0p1 (or later versions) to extract them.
.PP
For a brief help on \fIzip\fR and \fIunzip\fR,
run each without specifying any parameters on the command line.
.PP
The program is useful for packaging a set of files for distribution;
for archiving files;
and for saving disk space by temporarily
compressing unused files or directories.
.LP
The
.I zip
program puts one or more compressed files into a single
.I zip
archive,
along with information about the files
(name, path, date, time of last modification, protection,
and check information to verify file integrity).
An entire directory structure can be packed into a
.I zip
archive with a single command.
Compression ratios of 2:1 to 3:1 are common for text files.
.I zip
has one compression method (deflation) and can also store files without
compression.
.I zip
automatically chooses the better of the two for each file to be compressed.
.LP
The basic command format is
.IP
\fBzip\fR options archive inpattern inpattern ...
.LP
where \fBarchive\fR is a new or existing \fIzip\fR archive and \fBinpattern\fR is a directory or file path optionally including wildcards.
When given the name of an existing
.I zip
archive,
.I zip
will replace identically named entries in the
.I zip
archive or add entries for new names.
For example,
if
.I foo.zip
exists and contains
.I foo/file1
and
.IR foo/file2 ,
and the directory
.I foo
contains the files
.I foo/file1
and
.IR foo/file3 ,
then:
.IP
\fCzip -r foo.zip foo\fP
.LP
or more concisely
.IP
\fCzip -r foo foo\fP
.LP
will replace
.I foo/file1
in
.I foo.zip
and add
.I foo/file3
to
.IR foo.zip .
After this,
.I foo.zip
contains
.IR foo/file1 ,
.IR foo/file2 ,
and
.IR foo/file3 ,
with
.I foo/file2
unchanged from before.
.LP
If the file list is specified as
.BR \-@ ,
[Not on MacOS]
.I zip
takes the list of input files from standard input.
Under UNIX,
this option can be used to powerful effect in conjunction with the
.IR find (1)
command.
For example,
to archive all the C source files in the current directory and
its subdirectories:
.IP
\fCfind . -name "*.[ch]" -print | zip source -@\fP
.LP
(note that the pattern \fB"*.[ch]"\fR must be quoted to keep the shell from
expanding it).
.I zip
will also accept a single dash ("-") as the zip file name, in which case it
will write the zip file to standard output, allowing the output to be piped
to another program. For example:
.IP
\fCzip -r - . | dd of=/dev/nrst0 obs=16k\fP
.LP
would write the zip output directly to a tape with the specified block size
for the purpose of backing up the current directory.
.LP
.I zip
also accepts a single dash ("-") as the name of a file to be compressed, in
which case it will read the file from standard input, allowing zip to take
input from another program. For example:
.IP
\fCtar cf - . | zip backup -\fP
.LP
would compress the output of the tar command for the purpose of backing up
the current directory. This generally produces better compression than
the previous example using the
.B \-r
option, because
.I zip
can take advantage of redundancy between files. The backup can be restored
using the command
.IP
\fCunzip -p backup | tar xf -\fP
.LP
When no zip file name is given and stdout is not a terminal,
.I zip
acts as a filter, compressing standard input to standard output.
For example,
.IP
\fCtar cf - . | zip | dd of=/dev/nrst0 obs=16k\fP
.LP
is equivalent to
.IP
\fCtar cf - . | zip - - | dd of=/dev/nrst0 obs=16k\fP
.LP
.I zip
archives created in this manner can be extracted with the program
.I funzip
which is provided in the
.I unzip
package, or by
.I gunzip
which is provided in the
.I gzip
package. For example:
.IP
\fCdd if=/dev/nrst0  ibs=16k | funzip | tar xvf -\fP
.LP
When changing an existing
.I zip
archive,
.I zip
will write a temporary file with the new contents,
and only replace the old one when the process of creating the new version
has been completed without error.
.LP
If the name of the
.I zip
archive does not contain an extension, the extension
.IR .zip
is added. If the name already contains an extension other than
.IR .zip
the existing extension is kept unchanged.
.SH "OPTIONS"
.TP
.BI \-a
[Systems using EBCDIC] Translate file to ASCII format.
.TP
.BI \-A
Adjust self-extracting executable archive.
A self-extracting executable archive is created by prepending
the SFX stub to an existing archive. The
.B \-A
option tells
.I zip
to adjust the entry offsets stored
in the archive to take into account this "preamble" data.
.LP
Note: self-extracting archives for the Amiga are a special case.
At present, only the Amiga port of \fIzip\fR is capable of adjusting
or updating these without corrupting them.
.B \-J
can be used to remove the SFX stub if other updates need to be made.
.TP
.BI \-B
[VM/CMS and MVS] force file to be read binary (default is text).
.TP
.BI \-Bn
[TANDEM] set Edit/Enscribe formatting options with n defined as
.RS
bit  0: Don't add delimiter (Edit/Enscribe)
.RE
.RS
bit 1: Use LF rather than CR/LF as delimiter (Edit/Enscribe)
.RE
.RS
bit  2: Space fill record to maximum record length (Enscribe)
.RE
.RS
bit  3: Trim trailing space (Enscribe)
.RE
.RS
bit 8: Force 30K (Expand) large read for unstructured files
.RE
.TP
.BI \-b\ path
Use the specified
.I path
for the temporary
.I zip
archive. For example:
.RS
.IP
\fCzip -b /tmp stuff *\fP
.RE
.IP
will put the temporary
.I zip
archive in the directory
.IR /tmp ,
copying over
.I stuff.zip
to the current directory when done. This option is only useful when
updating an existing archive, and the file system containing this
old archive does not have enough space to hold both old and new archives
at the same time.
.TP
.B \-c
Add one-line comments for each file.
File operations (adding, updating) are done first,
and the user is then prompted for a one-line comment for each file.
Enter the comment followed by return, or just return for no comment.
.TP
.B \-d
Remove (delete) entries from a
.I zip
archive.
For example:
.RS
.IP
\fCzip -d foo foo/tom/junk foo/harry/\\* \\*.o\fP
.RE
.IP
will remove the entry
.IR foo/tom/junk ,
all of the files that start with
.IR foo/harry/ ,
and all of the files that end with
.I \&.o
(in any path).
Note that shell pathname expansion has been inhibited with backslashes,
so that
.I zip
can see the asterisks,
enabling
.I zip
to match on the contents of the
.I zip
archive instead of the contents of the current directory.
You can also use quotes to escape wildcards, as in
.RS
.IP
\fCzip -d foo foo/tom/junk "foo/harry/*" "*.o"\fP
.RE
.IP
Under systems where the shell does not expand wildcards, such as MSDOS,
the backslashes are not needed.  The above would then be
.RS
.IP
\fCzip -d foo foo/tom/junk foo/harry/* *.o\fP
.RE
.IP
Under MSDOS,
.B \-d
is case sensitive when it matches names in the
.I zip
archive.
This requires that file names be entered in upper case if they were
zipped by PKZIP on an MSDOS system.
.TP
.B \-df
[MacOS] Include only data-fork of files zipped into the archive.
Good for exporting files to foreign operating-systems.
Resource-forks will be ignored at all.
.TP
.B \-D
Do not create entries in the zip
archive for directories.  Directory entries are created by default so that
their attributes can be saved in the zip archive.
The environment variable ZIPOPT can be used to change the default options. For
example under Unix with sh:
.RS
.IP
ZIPOPT="-D"; export ZIPOPT
.RE
.IP
(The variable ZIPOPT can be used for any option except
.B \-i
and
.B \-x
and can include several options.) The option
.B \-D
is a shorthand
for
.B \-x
"*/" but the latter cannot be set as default in the ZIPOPT environment
variable.
.TP
.B \-e
Encrypt the contents of the zip
archive using a password which is entered on the terminal in response
to a prompt
(this will not be echoed; if standard error is not a tty,
.I zip
will exit with an error).
The password prompt is repeated to save the user from typing errors.
Note that this encrypts with standard pkzip encryption which is considered
weak.
.TP
.B \-E
[OS/2] Use the .LONGNAME Extended Attribute (if found) as filename.
.TP
.B \-f
Replace (freshen) an existing entry in the
.I zip
archive only if it has been modified more recently than the
version already in the
archive;
unlike the update option
.RB ( \-u )
this will not add files that are not already in the
.I zip
archive.
For example:
.RS
.IP
\fCzip -f foo\fP
.RE
.IP
This command should be run from the same directory from which the original
.I zip
command was run,
since paths stored in
.I zip
archives are always relative.
.IP
Note that the timezone environment variable TZ should be set according to
the local timezone in order for the
.B \-f
,
.B \-u
and
.B \-o
options to work correctly.
The reasons behind this are somewhat subtle but have to do with the differences
between the Unix-format file times (always in GMT) and most of the other
operating systems (always local time) and the necessity to compare the two.
A typical TZ value is ``MET-1MEST'' (Middle European time with automatic
adjustment for ``summertime'' or Daylight Savings Time).
.TP
.B \-F
Fix the
.I zip
archive. This option can be used if some portions of the archive
are missing. It is not guaranteed to work, so you MUST make a backup
of the original archive first.
.IP
When doubled as in
.B \-FF
the compressed sizes given inside the damaged archive are not trusted
and zip scans for special signatures to identify the limits between
the archive members. The single
.B \-F
is more reliable if the archive is not too much damaged, for example
if it has only been truncated, so try this option first.
.IP
Neither option will recover archives that have been incorrectly
transferred in ascii mode instead of binary. After the repair, the
.B \-t
option of
.I unzip
may show that some files have a bad CRC. Such files cannot be recovered;
you can remove them from the archive using the
.B \-d