Unzipping command in linux

» gets cancelled, but the old backup file is already lost. A similar scenario takes place when the sequence number range for numbered backup files gets exhausted (99999, or 65535 for 16-bit systems). In this case, the backup file with the maximum sequence number is deleted and replaced by the new backup version without notice. -C use case-insensitive matching for the selection of archive entries from the command-line list of extract selection patterns. unzip‘s philosophy is «you get what you ask for» (this is also responsible for the -L/-U change; see the relevant options below). Because some file systems are fully case-sensitive (notably those under the Unix operating system) and because both zip archives and unzip itself are portable across platforms, unzip‘s default behavior is to match both wildcard and literal filenames case-sensitively. That is, specifying «makefile» on the command line will only match «makefile in the archive, not «Makefile» or «MAKEFILE» (and similarly for wildcard specifications). Since this does not correspond to the behavior of many other operating/file systems (for example, OS/2 HPFS, which preserves mixed case but is not sensitive to it), the -C option may be used to force all filename matches to be case-insensitive. In the example above, all three files would then match «makefile» (or «make*, or similar). The -C option affects file specs in both the normal file list and the excluded-file list (xlist).

Please note that the -C option does neither affect the search for the zipfile(s) nor the matching of archive entries to existing files on the extraction path. On a case-sensitive file system, unzip will never try to overwrite a file «FOO» when extracting an entry «foo«! -D skip restoration of timestamps for extracted items. Normally, unzip tries to restore all meta-information for extracted items that are supplied in the Zip archive (and do not require privileges or impose a security risk). By specifying -D, unzip is told to suppress restoration of timestamps for directories explicitly created from Zip archive entries. This option only applies to ports that support setting timestamps for directories (currently ATheOS, BeOS, MacOS, OS/2, Unix, VMS, Win32; for other unzip ports, -D has no effect). The duplicated option -DD forces suppression of timestamp restoration for all extracted entries (files and directories). This option results in setting the timestamps for all extracted entries to the current time.

On VMS, the default setting for this option is -D for consistency with the behaviour of BACKUP: file timestamps are restored, timestamps of extracted directories are left at the current time. To enable restoration of directory timestamps, the negated option —D should be specified. On VMS, the option -D disables timestamp restoration for all extracted Zip archive items. (Here, a single -D on the command line combines with the default -D to do what an explicit -DD does on other systems.) -E [MacOS only] display contents of MacOS extra field during restore operation. -F [Acorn only] suppress removal of NFS filetype extension from stored filenames. -F [non-Acorn systems supporting long filenames with embedded commas, and only if compiled with ACORN_FTYPE_NFS defined] translate filetype information from ACORN RISC OS extra field blocks into an NFS filetype extension and append it to the names of the extracted files. (When the stored filename appears to already have an appended NFS filetype extension, it is replaced by the info from the extra field.) -i [MacOS only] ignore filenames stored in MacOS extra fields. Instead, the most compatible filename stored in the generic part of the entry’s header is used. -j junk paths. The archive’s directory structure is not recreated; all files are deposited in the extraction directory (by default, the current one). -J [BeOS only] junk file attributes. The file’s BeOS file attributes are not restored, just the file’s data. -J [MacOS only] ignore MacOS extra fields. All Macintosh specific info is skipped. Data-fork and resource-fork are restored as separate files. -K [AtheOS, BeOS, Unix only] retain SUID/SGID/Tacky file attributes. Without this flag, these attribute bits are cleared for security reasons. -L convert to lowercase any filename originating on an uppercase-only operating system or file system. (This was unzip’s default behavior in releases prior to 5.11; the new default behavior is identical to the old behavior with the -U option, which is now obsolete and will be removed in a future release.) Depending on the archiver, files archived under single-case file systems (VMS, old MS-DOS FAT, etc.) may be stored as all-uppercase names; this can be ugly or inconvenient when extracting to a case-preserving file system such as OS/2 HPFS or a case-sensitive one such as under Unix. By default, unzip lists and extracts such filenames exactly as they’re stored (excepting truncation, conversion of unsupported characters, etc.); this option causes the names of all files from certain systems to be converted to lowercase. The -LL option forces conversion of every filename to lowercase, regardless of the originating file system. -M pipe all output through an internal pager similar to the Unix more command. At the end of a screenful of output, unzip pauses with a «—More—» prompt; the next screenful may be viewed by pressing the Enter (Return) key or the spacebar. unzip can be terminated by pressing the «q» key and, on some systems, the Enter/Return key. Unlike Unix more, there is no forward-searching or editing capability. Also, unzip doesn’t notice if long lines wrap at the edge of the screen, effectively resulting in the printing of two or more lines and the likelihood that some text will scroll off the top of the screen before being viewed. On some systems the number of available lines on the screen is not detected, in which case unzip assumes the height is 24 lines. -n never overwrite existing files. If a file already exists, skip the extraction of that file without prompting. By default, unzip queries before extracting any file that already exists; the user may choose to overwrite only the current file, overwrite all files, skip extraction of the current file, skip extraction of all existing files, or rename the current file. -N [Amiga] extract file comments as Amiga filenotes. File comments are created with the -c option of zip, or with the -N option of the Amiga port of zip, which stores filenotes as comments. -o overwrite existing files without prompting. This is a dangerous option, so use it with care. (It is often used with -f, however, and is the only way to overwrite directory EAs under OS/2.) -P password use password to decrypt encrypted zipfile entries (if any). THIS IS INSECURE! Many multi-user operating systems provide ways for any user to see the current command line of any other user; even on stand-alone systems there is always the threat of over-the-shoulder peeking. Storing the plaintext password as part of a command line in an automated script is even worse. Whenever possible, use the non-echoing, interactive prompt to enter passwords. (And where security is truly important, use strong encryption such as Pretty Good Privacy instead of the relatively weak encryption provided by standard zipfile utilities.) -q perform operations quietly (-qq = even quieter). Ordinarily unzip prints the names of the files it’s extracting or testing, the extraction methods, any file or zipfile comments that may be stored in the archive, and possibly a summary when finished with each archive. The -q[q] options suppress the printing of some or all of these messages. -s [OS/2, NT, MS-DOS] convert spaces in filenames to underscores. Since all PC operating systems allow spaces in filenames, unzip by default extracts filenames with spaces intact (e.g., «EA DATA. SF«). This can be awkward, however, since MS-DOS in particular does not gracefully support spaces in filenames. Conversion of spaces to underscores can eliminate the awkwardness in some cases. -S [VMS] convert text files (-a, -aa) into Stream_LF record format, instead of the text-file default, variable-length record format. (Stream_LF is the default record format of VMS unzip. It is applied unless conversion (-a, -aa and/or -b, -bb) is requested or a VMS-specific entry is processed.) -U [UNICODE_SUPPORT only] modify or disable UTF-8 handling. When UNICODE_SUPPORT is available, the option -U forces unzip to escape all non-ASCII characters from UTF-8 coded filenames as «#Uxxxx» (for UCS-2 characters, or «#Lxxxxxx» for unicode codepoints needing 3 octets). This option is mainly provided for debugging purpose when the fairly new UTF-8 support is suspected to mangle up extracted filenames.

The option -UU allows to entirely disable the recognition of UTF-8 encoded filenames. The handling of filename codings within unzip falls back to the behaviour of previous versions.

[old, obsolete usage] leave filenames uppercase if created under MS-DOS, VMS, etc. See -L above. -V retain (VMS) file version numbers. VMS files can be stored with a version number, in the format file.ext;##. By default, the «;##» version numbers are stripped, but this option allows them to be retained. (On file systems that limit filenames to particularly short lengths, the version numbers may be truncated or stripped regardless of this option.) -W [only when WILD_STOP_AT_DIR compile-time option enabled] modifies the pattern matching routine so that both ‘?‘ (single-char wildcard) and ‘*‘ (multi-char wildcard) do not match the directory separator character ‘/‘. (The two-character sequence «**» acts as a multi-char wildcard that includes the directory separator in its matched characters.) Examples:

• «*.c» matches «foo.c» but not «mydir/foo.c«
• «**.c» matches both «foo.c» and «mydir/foo.c«
• «*/*.c» matches «bar/foo.c» but not «baz/bar/foo.c«
• «??*/*» matches «ab/foo» and «abc/foo» but not «a/foo» or «a/b/foo«

This modified behaviour is equivalent to the pattern matching style used by the shells of some of UnZip’s supported target OSs (one example is Acorn RISC OS). This option may not be available on systems where the Zip archive’s internal directory separator character ‘/‘ is allowed as regular character in native operating system filenames. (Currently, unzip uses the same pattern matching rules for both wildcard zipfile specifications and zip entry selection patterns in most ports. For systems allowing `/‘ as regular filename character, the -W option would not work as expected on a wildcard zipfile specification.) -X [VMS, Unix, OS/2, NT, Tandem] restore owner/protection info (UICs and ACL entries) under VMS, or user and group info (UID/GID) under Unix, or access control lists (ACLs) under certain network-enabled versions of OS/2 (Warp Server with IBM LAN Server/Requester 3.0 to 5.0; Warp Connect with IBM Peer 1.0), or security ACLs under Windows NT. In most cases this will require special system privileges, and doubling the option (-XX) under NT instructs unzip to use privileges for extraction; but under Unix, for example, a user who belongs to several groups can restore files owned by any of those groups, as long as the user IDs match his or her own. Note that ordinary file attributes are always restored—this option applies only to optional, extra ownership info available on some operating systems. [NT’s access control lists do not appear to be especially compatible with OS/2’s, so no attempt is made at cross-platform portability of access privileges.] -Y [VMS] treat archived file name endings of «.nnn» (where «nnn» is a decimal number) as if they were VMS version numbers («;nnn«). (The default is to treat them as file types.) Example: «a.b.3» -> «a.b;3«. -$ [MS-DOS, OS/2, NT] restore the volume label if the extraction medium is removable (e.g., a diskette). Doubling the option (-$$) allows fixed media (hard disks) to be labelled as well. By default, volume labels are ignored. -/extensions [Acorn only] overrides the extension list supplied by the Unzip$Ext environment variable. During extraction, filename extensions that match one of the items in this extension list are swapped in front of the base name of the extracted file. -: [all but Acorn, VM/CMS, MVS, Tandem] allows to extract archive members into locations outside of the current «extraction root folder». For security reasons, unzip normally removes «parent dir» path components («../«) from the names of extracted file. This safety feature (new for version 5.50) prevents unzip from accidentally writing files to «sensitive» areas outside the active extraction folder tree head. The -: option lets unzip switch back to its previous, more liberal behaviour, to allow exact extraction of (older) archives that used «../» components to create multiple directory trees at the level of the current extraction folder. This option does not enable writing explicitly to the root directory («/«). To achieve this, it is necessary to set the extraction target folder to root (e.g., -d / ). However, when the -: option is specified, it is still possible to implicitly write to the root directory by specifying enough «../» path components within the zip archive. Use this option with extreme caution. -^ [Unix only] allow control characters in names of extracted zip archive entries. On Unix, a file name may contain any (8-bit) character code with the two exception ‘/‘ (directory delimiter) and NUL (0x00, the C string termination indicator), unless the specific file system has more restrictive conventions. Generally, this allows to embed ASCII control characters (or even sophisticated control sequences) in file names, at least on ‘native’ Unix file systems. However, it may be highly suspicious to make use of this Unix «feature». Embedded control characters in file names might have nasty side effects when displayed on the screen by some listing code without sufficient filtering. And, for ordinary users, it may be difficult to handle such file names (e.g., when trying to specify it for open, copy, move, or delete operations). Therefore, unzip applies a filter by default that removes potentially dangerous control characters from the extracted file names. The -^ option allows to override this filter in the rare case that embedded filename control characters are to be intentionally restored. -2 [VMS] force unconditionally conversion of file names to ODS2-compatible names. The default is to exploit the destination file system, preserving case and extended file name characters on an ODS5 destination file system; and applying the ODS2-compatibility file name filtering on an ODS2 destination file system.

Options

unzip‘s default behavior may be modified via options placed in an environment variable. This can be done with any option, but it is probably most useful with the -a, -L, -C, -q, -o, or -n modifiers: make unzip auto-convert text files by default, make it convert filenames from uppercase systems to lowercase, make it match names case-insensitively, make it quieter, or make it always overwrite or never overwrite files as it extracts them. For example, to make unzip act as quietly as possible, only reporting errors, one would use one of the following commands:

VMS (quotes for lowercase):

Environment options are, in effect, considered to be just like any other command-line options, except that they are effectively the first options on the command line. To override an environment option, one may use the «minus operator» to remove it. For instance, to override one of the quiet-flags in the example above, use the command below.

The first hyphen is the normal switch character, and the second is a minus sign, acting on the q option. Thus the effect here is to cancel one quantum of quietness. To cancel both quiet flags, two (or more) minuses may be used:

(the two are equivalent). This may seem awkward or confusing, but it is reasonably intuitive: just ignore the first hyphen and go from there. It is also consistent with the behavior of Unix nice.

As suggested by the examples above, the default variable names are UNZIP_OPTS for VMS (where the symbol used to install unzip as a foreign command would otherwise be confused with the environment variable), and UNZIP for all other operating systems. For compatibility with zip, UNZIPOPT is also accepted. If both UNZIP and UNZIPOPT are defined, however, UNZIP takes precedence. unzip‘s diagnostic option (-v with no zipfile name) can be used to check the values of all four possible unzip and zipinfo environment variables.

The timezone variable (TZ) should be set according to the local timezone for the -f and -u to operate correctly. See the description of -f above for details. This variable may also be necessary to get timestamps of extracted files to be set correctly. The WIN32 (Win9x/ME/NT4/2K/XP/2K3) port of unzip gets the timezone configuration from the Registry, assuming it is correctly set in the Control Panel. The TZ variable is ignored for this port.

Decryption

Encrypted archives are fully supported by Info-ZIP software, but due to United States export restrictions, de-/encryption support might be disabled in your particular compiled binary. However, since the spring of 2000, US export restrictions have been liberated, and our source archives do now include full crypt code. In case you need binary distributions with crypt support enabled, see the file «WHERE» in any Info-ZIP source or binary distribution for locations both inside and outside the US.

Some compiled versions of unzip may not support decryption. To check a version for crypt support, either attempt to test or extract an encrypted archive, or else check unzip‘s diagnostic screen (see the -v option above) for «[decryption]» as one of the special compilation options.

As noted above, the -P option may be used to supply a password on the command line, but at a cost in security. The preferred decryption method is to extract normally; if a zipfile member is encrypted, unzip will prompt for the password without echoing what is typed. unzip continues to use the same password as long as it appears to be valid, by testing a 12-byte header on each file. The correct password will always check out against the header, but there is a 1-in-256 chance that an incorrect password will as well. (This is a security feature of the PKWARE zipfile format; it helps prevent brute-force attacks that might otherwise gain a large speed advantage by testing only the header.) In the case that an incorrect password is given but it passes the header test anyway, either an incorrect CRC will be generated for the extracted data or else unzip will fail during the extraction because the «decrypted» bytes do not constitute a valid compressed data stream.

If the first password fails the header check on some file, unzip will prompt for another password, and so on until all files are extracted. If a password is not known, entering a null password (that is, just a carriage return or «Enter») is taken as a signal to skip all further prompting. Only unencrypted files in the archive(s) will thereafter be extracted. (In fact, that’s not quite true; older versions of zip and zipcloak allowed null passwords, so unzip checks each encrypted file to see if the null password works. This may result in «false positives» and extraction errors, as noted above.)

Archives encrypted with 8-bit passwords (for example, passwords with accented European characters) may not be portable across systems and/or other archivers. This problem stems from the use of multiple encoding methods for such characters, including Latin-1 (ISO 8859-1) and OEM code page 850. DOS PKZIP 2.04g uses the OEM code page; Windows PKZIP 2.50 uses Latin-1 (and is therefore incompatible with DOS PKZIP); Info-ZIP uses the OEM code page on DOS, OS/2 and Win3.x ports but ISO coding (Latin-1 etc.) everywhere else; and Nico Mak’s WinZip 6.x does not allow 8-bit passwords at all. unzip 5.3 (or newer) attempts to use the default character set first (e.g., Latin-1), followed by the alternate one (e.g., OEM code page) to test passwords. On EBCDIC systems, if both of these fail, EBCDIC encoding will be tested as a last resort. (EBCDIC is not tested on non-EBCDIC systems, because there are no known archivers that encrypt using EBCDIC encoding.) ISO character encodings other than Latin-1 are not supported. The new addition of (partially) Unicode (resp. UTF-8) support in UnZip 6.0 has not yet been adapted to the encryption password handling in unzip. On systems that use UTF-8 as native character encoding, unzip tries decryption with the native UTF-8 encoded password; the built-in attempts to check the password in translated encoding have not yet been adapted for UTF-8 support and will consequently fail.

Examples

Unzip the hope.zip archive into the current directory, creating subdirectories as needed to match the archive’s file hierarchy.

Extract the files from archive hope.zip into the current directory only, regardless of the archive’s internal directory structure.

Test hope.zip for errors, but do not extract anything. The q indicates «quiet» mode, which instructs unzip to return only a summary message, rather than a more detailed one.

Display the contents of all files with the extension .txt contained in the archive hope.zip to the standard output.

Extract from the hope.zip archive any C source files with the extensions .c and .h, and any files named Makefile, into the directory /tmp.

Same as the above command, but case-insensitive; it will also extract any files with the extensions .C or .H, any files named MAKEFILE, any files named MakeFile, etc.

Extract files from the archive hope.zip, but only if they are newer versions than the files that already exist.

Display a listing of the contents of hope.zip without extracting anything.

Related commands

gzip — Create, modify, list the contents of, and extract files from GNU zip archives.
zip — A compression and archiving utility.
zipinfo — Display technical information about a zip file.

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