the -o option may
be used to suppress the queries. Note that under many operating
systems, the TZ (timezone) environment variable must be set cor‐
rectly in order for -f and -u to work properly (under Unix the
variable is usually set automatically). The reasons for this are
somewhat subtle but have to do with the differences between DOS‐
format file times (always local time) and Unix‐format times (al‐
ways in GMT/UTC) and the necessity to compare the two. A typical
TZ value is ‘‘PST8PDT’’ (US Pacific time with automatic adjust‐
ment for Daylight Savings Time or ‘‘summer time’’).
-l list archive files (short format). The names, uncompressed file
sizes and modification dates and times of the specified files are
printed, along with totals for all files specified. If UnZip was
compiled with OS2_EAS defined, the -l option also lists columns
for the sizes of stored OS/2 extended attributes (EAs) and OS/2
access control lists (ACLs). In addition, the zipfile comment
and individual file comments (if any) are displayed. If a file
was archived from a single‐case file system (for example, the old
MS‐DOS FAT file system) and the -L option was given, the filename
is converted to lowercase and is prefixed with a caret (^).
-p extract files to pipe (stdout). Nothing but the file data is
sent to stdout, and the files are always extracted in binary for‐
mat, just as they are stored (no conversions).
-t test archive files. This option extracts each specified file in
memory and compares the CRC (cyclic redundancy check, an enhanced
checksum) of the expanded file with the original file’s stored
CRC value.
-T [most OSes] set the timestamp on the archive(s) to that of the
newest file in each one. This corresponds to zip’s -go option
except that it can be used on wildcard zipfiles (e.g., ‘‘unzip -T
\*.zip’’) and is much faster.
-u update existing files and create new ones if needed. This option
performs the same function as the -f option, extracting (with
query) files that are newer than those with the same name on
disk, and in addition it extracts those files that do not already
exist on disk. See -f above for information on setting the time‐
zone properly.
-v list archive files (verbose format) or show diagnostic version
info. This option has evolved and now behaves as both an option
and a modifier. As an option it has two purposes: when a zip‐
file is specified with no other options, -v lists archive files
verbosely, adding to the basic -l info the compression method,
compressed size, compression ratio and 32‐bit CRC. In contrast
to most of the competing utilities, unzip removes the 12 addi‐
tional header bytes of encrypted entries from the compressed size
numbers. Therefore, compressed size and compression ratio fig‐
ures are independent of the entry’s encryption status and show
the correct compression performance. (The complete size of the
encrypted compressed data stream for zipfile entries is reported
by the more verbose zipinfo(1) reports, see the separate manual.)
When no zipfile is specified (that is, the complete command is
simply ‘‘unzip -v’’), a diagnostic screen is printed. In addi‐
tion to the normal header with release date and version, unzip