pax [-0cdJjnOvz] [-E limit] [-f archive] [-G group] [-s replstr]
[-T range] [-U user] [pattern ...]
pax -r [-0cDdiJjknOuvYZz] [-E limit] [-f archive] [-G group] [-M flag]
[-o options] [-p string] [-s replstr] [-T range] [-U user]
pax -w [-0adHiJjLOPtuvXz] [-B bytes] [-b blocksize] [-f archive]
[-G group] [-M flag] [-o options] [-s replstr] [-T range] [-U user]
[-x format] [file ...]
pax -rw [-0DdHiJjkLlnOPtuvXYZ] [-G group] [-p string] [-s replstr]
[-T range] [-U user] [file ...] directory
pax will read, write, and list the members of an archive file and will
copy directory hierarchies. pax operation is independent of the specific
archive format and supports a wide variety of different archive formats.
A list of supported archive formats can be found under the description of
the -x option.
The presence of the -r and the -w options specifies which of the follow-
ing functional modes pax will operate under: list, read, write, and copy.
<none> List. pax will write to standard output a table of contents of
the members of the archive file read from standard input, whose
pathnames match the specified pattern arguments. The table of
contents contains one filename per line and is written using sin-
gle line buffering.
-r Read. pax extracts the members of the archive file read from the
standard input, with pathnames matching the specified pattern
arguments. The archive format and blocking is automatically
determined on input. When an extracted file is a directory, the
entire file hierarchy rooted at that directory is extracted. All
extracted files are created relative to the current file hierar-
chy. The setting of ownership, access and modification times,
and file mode of the extracted files are discussed in more detail
under the -p option.
-w Write. pax writes an archive containing the file operands to
standard output using the specified archive format. When no file
operands are specified, a list of files to copy with one per line
is read from standard input. When a file operand is also a
directory, the entire file hierarchy rooted at that directory
will be included.
-rw Copy. pax copies the file operands to the destination directory.
When no file operands are specified, a list of files to copy with
one per line is read from the standard input. When a file oper-
and is also a directory the entire file hierarchy rooted at that
directory will be included. The effect of the copy is as if the
copied files were written to an archive file and then subse-
quently extracted, except that there may be hard links between
the original and the copied files (see the -l option below).
Warning: The destination directory must not be one of the file
The pattern operand is used to select one or more pathnames of archive
members. Archive members are selected using the pattern matching nota-
tion described by glob(3). When the pattern operand is not supplied, all
members of the archive will be selected. When a pattern matches a direc-
tory, the entire file hierarchy rooted at that directory will be
selected. When a pattern operand does not select at least one archive
member, pax will write these pattern operands in a diagnostic message to
standard error and then exit with a non-zero exit status.
The file operand specifies the pathname of a file to be copied or
archived. When a file operand does not select at least one archive mem-
ber, pax will write these file operand pathnames in a diagnostic message
to standard error and then exit with a non-zero exit status.
The options are as follows:
-0 Use the NUL ('\0') character as a pathname terminator, instead of
newline ('\n'). This applies only to the pathnames read from
standard input in the write and copy modes, and to the pathnames
written to standard output in list mode. This option is expected
to be used in concert with the -print0 function in find(1) or the
-0 flag in xargs(1).
-a Append the given file operands to the end of an archive that was
previously written. If an archive format is not specified with a
-x option, the format currently being used in the archive will be
selected. Any attempt to append to an archive in a format dif-
ferent from the format already used in the archive will cause pax
to exit immediately with a non-zero exit status. The blocking
size used in the archive volume where writing starts will con-
tinue to be used for the remainder of that archive volume.
Warning: Many storage devices are not able to support the opera-
tions necessary to perform an append operation. Any attempt to
append to an archive stored on such a device may damage the ar-
chive or have other unpredictable results. Tape drives in par-
ticular are more likely to not support an append operation. An
archive stored in a regular file system file or on a disk device
will usually support an append operation.
Limit the number of bytes written to a single archive volume to
bytes. The bytes limit can end with 'm', 'k', or 'b' to specify
multiplication by 1048576 (1M), 1024 (1K) or 512, respectively.
A pair of bytes limits can be separated by 'x' to indicate a
Warning: Only use this option when writing an archive to a device
which supports an end of file read condition based on last (or
largest) write offset (such as a regular file or a tape drive).
The use of this option with a floppy or hard disk is not recom-
(see the -x option).
-c Match all file or archive members except those specified by the
pattern and file operands.
-D This option is the same as the -u option, except that the file
inode change time is checked instead of the file modification
time. The file inode change time can be used to select files
whose inode information (e.g., UID, GID, etc.) is newer than a
copy of the file in the destination directory.
-d Cause files of type directory being copied or archived, or ar-
chive members of type directory being extracted, to match only
the directory file or archive member and not the file hierarchy
rooted at the directory.
Limit the number of consecutive read faults while trying to read
a flawed archive to limit. With a positive limit, pax will
attempt to recover from an archive read error and will continue
processing starting with the next file stored in the archive. A
limit of 0 will cause pax to stop operation after the first read
error is detected on an archive volume. A limit of NONE will
cause pax to attempt to recover from read errors forever. The
default limit is a small positive number of retries.
Warning: Using this option with NONE should be used with extreme
caution as pax may get stuck in an infinite loop on a very badly
Specify archive as the pathname of the input or output archive,
overriding the default standard input (for list and read) or
standard output (for write). A single archive may span multiple
files and different archive devices. When required, pax will
prompt for the pathname of the file or device of the next volume
in the archive.
Select a file based on its group name, or when starting with a #,
a numeric GID. A '\' can be used to escape the #. Multiple -G
options may be supplied and checking stops with the first match.
-H Follow only command-line symbolic links while performing a physi-
cal file system traversal.
-i Interactively rename files or archive members. For each archive
member matching a pattern operand or each file matching a file
operand, pax will prompt to /dev/tty giving the name of the file,
its file mode, and its modification time. pax will then read a
line from /dev/tty. If this line is blank, the file or archive
member is skipped. If this line consists of a single period, the
file or archive member is processed with no modification to its
name. Otherwise, its name is replaced with the contents of the
-L Follow all symbolic links to perform a logical file system tra-
-l (The lowercase letter ``ell''.) Link files. In the copy mode
(-r -w), hard links are made between the source and destination
file hierarchies whenever possible.
Configure the archive normaliser. flag is either a numeric value
compatible to strtonum(3) which is directly stored in the flags
word, or one of the following values, optionally prefixed with
``no-'' to turn them off:
inodes 0x0001: Serialise inodes, zero device info.
(cpio, sv4cpio, sv4crc)
links 0x0002: Store content of hard links only once.
(cpio, sv4cpio, sv4crc)
mtime 0x0004: Zero out the file modification time.
(ar, cpio, sv4cpio, sv4crc, ustar)
uidgid 0x0008: Set owner to 0:0 (root:wheel).
(ar, cpio, sv4cpio, sv4crc, ustar)
verb 0x0010: Debug this option.
debug 0x0020: Debug file header storage.
lncp 0x0040: Extract hard links by copy if link fails.
numid 0x0080: Use only numeric uid and gid values.
gslash 0x0100: Append a slash after directory names.
set 0x0003: Keep ownership and mtime intact.
dist 0x008B: Clean everything except mtime.
norm 0x008F: Clean everything.
root 0x0089: Clean owner and device information.
This option is only implemented for the ar, cpio, sv4cpio,
sv4crc, and ustar file format writing routines.
TODO: The pax frontend should be using the -o option for handling
this feature instead.
-n Select the first archive member that matches each pattern oper-
and. No more than one archive member is matched for each
pattern. When members of type directory are matched, the file
hierarchy rooted at that directory is also matched (unless -d is
-O Force the archive to be one volume. If a volume ends prema-
turely, pax will not prompt for a new volume. This option can be
useful for automated tasks where error recovery cannot be per-
formed by a human.
Information to modify the algorithm for extracting or writing ar-
chive files which is specific to the archive format specified by
-x. In general, options take the form: name=value.
The string option-argument is a string specifying file character-
istics to be retained or discarded on extraction. The string
consists of the specification characters a, e, m, o, and p. Mul-
tiple characteristics can be concatenated within the same string
and multiple -p options can be specified. The meanings of the
specification characters are as follows:
a Do not preserve file access times. By default, file access
times are preserved whenever possible.
e ``Preserve everything'', the user ID, group ID, file mode
bits, file access time, and file modification time. This is
intended to be used by root, someone with all the appropriate
privileges, in order to preserve all aspects of the files as
they are recorded in the archive. The e flag is the sum of
the o and p flags.
m Do not preserve file modification times. By default, file
modification times are preserved whenever possible.
o Preserve the user ID and group ID.
p ``Preserve'' the file mode bits. This is intended to be used
by a user with regular privileges who wants to preserve all
aspects of the file other than the ownership. The file times
are preserved by default, but two other flags are offered to
disable this and use the time of extraction instead.
In the preceding list, 'preserve' indicates that an attribute
stored in the archive is given to the extracted file, subject to
the permissions of the invoking process. Otherwise the attribute
of the extracted file is determined as part of the normal file
creation action. If neither the e nor the o specification char-
acter is specified, or the user ID and group ID are not preserved
for any reason, pax will not set the S_ISUID (setuid) and S_ISGID
(setgid) bits of the file mode. If the preservation of any of
these items fails for any reason, pax will write a diagnostic
message to standard error. Failure to preserve these items will
affect the final exit status, but will not cause the extracted
file to be deleted. If the file characteristic letters in any of
the string option-arguments are duplicated or conflict with each
other, the one(s) given last will take precedence. For example,
if -p eme is specified, file modification times are still pre-
-r Read an archive file from standard input and extract the speci-
fied file operands. If any intermediate directories are needed
in order to extract an archive member, these directories will be
created as if mkdir(2) was called with the bitwise inclusive OR
of S_IRWXU, S_IRWXG, and S_IRWXO as the mode argument. When the
selected archive format supports the specification of linked
files and these files cannot be linked while the archive is being
extracted, pax will write a diagnostic message to standard error
and exit with a non-zero exit status at the completion of opera-
As in ed(1), old is a basic regular expression (see re_format(7))
and new can contain an ampersand ('&'), '\n' (where n is a digit)
back-references, or subexpression matching. The old string may
also contain newline characters. Any non-null character can be
used as a delimiter ('/' is shown here). Multiple -s expressions
can be specified. The expressions are applied in the order they
are specified on the command line, terminating with the first
The optional trailing g continues to apply the substitution
expression to the pathname substring, which starts with the first
character following the end of the last successful substitution.
The first unsuccessful substitution stops the operation of the g
option. The optional trailing p will cause the final result of a
successful substitution to be written to standard error in the
original-pathname >> new-pathname
File or archive member names that substitute to the empty string
are not selected and will be skipped.
Allow files to be selected based on a file modification or inode
change time falling within the specified time range. The range
has the format:
The dates specified by from_date to to_date are inclusive. If
only a from_date is supplied, all files with a modification or
inode change time equal to or younger are selected. If only a
to_date is supplied, all files with a modification or inode
change time equal to or older will be selected. When the
from_date is equal to the to_date, only files with a modification
or inode change time of exactly that time will be selected.
When pax is in the write or copy mode, the optional trailing
field [c][m] can be used to determine which file time (inode
change, file modification or both) are used in the comparison.
If neither is specified, the default is to use file modification
time only. The m specifies the comparison of file modification
time (the time when the file was last written). The c specifies
the comparison of inode change time (the time when the file inode
was last changed; e.g., a change of owner, group, mode, etc).
When c and m are both specified, then the modification and inode
change times are both compared.
The inode change time comparison is useful in selecting files
whose attributes were recently changed or selecting files which
were recently created and had their modification time reset to an
older time (as what happens when a file is extracted from an ar-
chive and the modification time is preserved). Time comparisons
using both file times is useful when pax is used to create a time
59), and SS is the seconds (from 00 to 59). The minute field MM
is required, while the other fields are optional and must be
added in the following order: HH, dd, mm, yy, cc.
The SS field may be added independently of the other fields.
Time ranges are relative to the current time, so -T 1234/cm would
select all files with a modification or inode change time of
12:34 PM today or later. Multiple -T time range can be supplied
and checking stops with the first match.
-t Reset the access times of any file or directory read or accessed
by pax to be the same as they were before being read or accessed
Select a file based on its user name, or when starting with a #,
a numeric UID. A '\' can be used to escape the #. Multiple -U
options may be supplied and checking stops with the first match.
-u Ignore files that are older (having a less recent file modifica-
tion time) than a pre-existing file or archive member with the
same name. During read, an archive member with the same name as
a file in the file system will be extracted if the archive member
is newer than the file. During write, a file system member with
the same name as an archive member will be written to the archive
if it is newer than the archive member. During copy, the file in
the destination hierarchy is replaced by the file in the source
hierarchy or by a link to the file in the source hierarchy if the
file in the source hierarchy is newer.
-v During a list operation, produce a verbose table of contents
using the format of the ls(1) utility with the -l option. For
pathnames representing a hard link to a previous member of the
archive, the output has the format:
ls -l listing == link-name
For pathnames representing a symbolic link, the output has the
ls -l listing => link-name
Where ls -l listing is the output format specified by the ls(1)
utility when used with the -l option. Otherwise for all the
other operational modes (read, write, and copy), pathnames are
written and flushed to standard error without a trailing newline
as soon as processing begins on that file or archive member. The
trailing newline is not buffered and is written only after the
file has been read or written.
-w Write files to the standard output in the specified archive for-
mat. When no file operands are specified, standard input is read
for a list of pathnames with one per line without any leading or
GNU binutils (which can however read them) or SYSV sys-
tems. See ar(5) on some operating systems for more
bcpio The old binary cpio format. The default blocksize for
this format is 5120 bytes. This format is not very por-
table and should not be used when other formats are
available. Inode and device information about a file
(used for detecting file hard links by this format),
which may be truncated by this format, is detected by
pax and is repaired.
cpio The extended cpio interchange format specified in the
IEEE Std 1003.2 (``POSIX.2'') standard. The default
blocksize for this format is 5120 bytes. Inode and
device information about a file (used for detecting file
hard links by this format), which may be truncated by
this format, is detected by pax and is repaired.
sv4cpio The System V release 4 cpio. The default blocksize for
this format is 5120 bytes. Inode and device information
about a file (used for detecting file hard links by this
format), which may be truncated by this format, is
detected by pax and is repaired.
sv4crc The System V release 4 cpio with file CRC checksums.
The default blocksize for this format is 5120 bytes.
Inode and device information about a file (used for
detecting file hard links by this format), which may be
truncated by this format, is detected by pax and is
tar The old BSD tar format as found in 4.3BSD. The default
blocksize for this format is 10240 bytes. Pathnames
stored by this format must be 100 characters or less in
length. Only regular files, hard links, soft links, and
directories will be archived (other file system types
are not supported). For backwards compatibility with
even older tar formats, a -o option can be used when
writing an archive to omit the storage of directories.
This option takes the form:
ustar The extended tar interchange format specified in the
IEEE Std 1003.2 (``POSIX.2'') standard. The default
blocksize for this format is 10240 bytes. Filenames
stored by this format must be 100 characters or less in
length; the total pathname must be 256 characters or
pax will detect and report any file that it is unable to store or
extract as the result of any specific archive format restric-
tions. The individual archive formats may impose additional
-z Use the gzip(1) utility to compress (decompress) the archive
while writing (reading). Incompatible with -a.
The options that operate on the names of files or archive members (-c,
-i, -n, -s, -u, -v, -D, -G, -T, -U, -Y, and -Z) interact as follows.
When extracting files during a read operation, archive members are
'selected', based only on the user specified pattern operands as modified
by the -c, -n, -u, -D, -G, -T, -U options. Then any -s and -i options
will modify in that order, the names of these selected files. Then the
-Y and -Z options will be applied based on the final pathname. Finally,
the -v option will write the names resulting from these modifications.
When archiving files during a write operation, or copying files during a
copy operation, archive members are 'selected', based only on the user
specified pathnames as modified by the -n, -u, -D, -G, -T, and -U options
(the -D option only applies during a copy operation). Then any -s and -i
options will modify in that order, the names of these selected files.
Then during a copy operation the -Y and the -Z options will be applied
based on the final pathname. Finally, the -v option will write the names
resulting from these modifications.
When one or both of the -u or -D options are specified along with the -n
option, a file is not considered selected unless it is newer than the
file to which it is compared.
TMPDIR Path in which to store temporary files.
The pax utility exits with one of the following values:
0 All files were processed successfully.
1 An error occurred.
Copy the contents of the current directory to the device /dev/rst0:
$ pax -w -f /dev/rst0 .
Give the verbose table of contents for an archive stored in filename:
$ pax -v -f filename
This sequence of commands will copy the entire olddir directory hierarchy
$ mkdir newdir
$ cd olddir
$ pax -rw . ../newdir
Extract files from the archive a.pax. Files rooted in /usr are extracted
relative to the current working directory; all other files are extracted
to their unmodified path.
Update (and list) only those files in the destination directory /backup
which are older (less recent inode change or file modification times)
than files with the same name found in the source file tree home:
$ pax -r -w -v -Y -Z home /backup
Whenever pax cannot create a file or a link when reading an archive or
cannot find a file when writing an archive, or cannot preserve the user
ID, group ID, or file mode when the -p option is specified, a diagnostic
message is written to standard error and a non-zero exit status will be
returned, but processing will continue. In the case where pax cannot
create a link to a file, unless -M lncp is given, pax will not create a
second copy of the file.
If the extraction of a file from an archive is prematurely terminated by
a signal or error, pax may have only partially extracted a file the user
wanted. Additionally, the file modes of extracted files and directories
may have incorrect file bits, and the modification and access times may
If the creation of an archive is prematurely terminated by a signal or
error, pax may have only partially created the archive, which may violate
the specific archive format specification.
If while doing a copy, pax detects a file is about to overwrite itself,
the file is not copied, a diagnostic message is written to standard error
and when pax completes it will exit with a non-zero exit status.
ar(1), cpio(1), deb(5), paxcpio(1), paxtar(1), tar(1)
The pax utility is compliant with the IEEE Std 1003.1-2008 (``POSIX'')
The flags -0BDEGHJjLMOPTUYZz, the archive formats ar, bcpio, sv4cpio,
sv4crc, tar, and the flawed archive handling during list and read opera-
tions are extensions to that specification.
Keith Muller at the University of California, San Diego.
MirOS extensions by Thorsten Glaser <email@example.com>.
The pax file format is not yet supported.
MirBSD June 5, 2012 MirBSD
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