unpack — Decode Huffman packed files
Format
unpack file…
Note: The unpack utility
is fully supported for compatibility with older UNIX systems.
However, it is recommended that the uncompress utility
be used instead because it may provide greater functionality and is
considered the standard for portable UNIX applications
as defined by POSIX.2 IEEE standard 1003.2-1992.
Description
unpack uncompresses files compressed by pack, using a Huffman minimal redundancy code. By default, unpack looks for file with a .z extension. It places the decompressed output in a file with the same name, but without the extension. The owner, permissions, and times of last access and last modification are also preserved. Packed files can be identified by file. You can use pcat to view packed text files without unpacking them in place.
unpack does
not unpack a file if:
- The file name is too long after the .z is removed
- The input file cannot be opened
- An existing file has the same name as the output file
- The output file can't be created
- The input file doesn't appear to have been created by pack
Localization
unpack uses
the following localization environment variables:
- LANG
- LC_ALL
- LC_COLLATE
- LC_CTYPE
- LC_MESSAGES
- NLSPATH
See Localization for more information.
Files
unpack uses
the following file:
- pk$*
- Temporary copy of input file. (You may see this in the current directory if unpack is interrupted.) The file is in the same directory as the file being unpacked.
Exit values
- 0
- Successful completion
- n
- Indicates that files could not be unpacked properly. For example,
if three out of six files could not be unpacked properly, the exit
status is 3. Possible reasons for failure include:
- Unknown command-line option
- Error creating a name for a temporary file
- Error opening an input file or a temporary file
- Error writing to a temporary file
- Inability to rename a temporary file
- Inability to restore the modification time on a packed file
- Input file was not packed
- A packed file is corrupted
Messages
Possible error messages include:
- file: Not a packed file
- pack did not process the file. In this case, the file is not changed.
Portability
POSIX.2, X/Open Portability Guide, UNIX systems.
Related information
file, pack, pcat