pax(1)
pax --
portable archive interchange
Synopsis
/u95/bin/pax [-cdnv] [-f archive] [-s replstr][pattern...]
pax -r [-cdiknuvy] [-f archive][-p string][-s replstr] [pattern...]
pax -w[-dituvyX] [-b blocksize] [[-a] -f archive][-s replstr]
[-x format][file...]
pax -r -w [-diklntuvyX][-p string][-s replstr][file...] directory
Description
The
pax
utility reads, writes, and lists members of archive files, and copies
directory hierarchies.
A variety of archive formats are supported;
see the
-x
format
option.
The four forms listed in the SYNOPSIS section
are referred to as modes of operation.
These modes represent the different combinations of the
-r
and
-w
options.
The four modes of operation are
``list'', ``read'', ``write'' and ``copy''.
pattern
is a pattern matching one or more pathnames of archive members.
The default, if no
pattern
is specified, is to select all members in the archive.
directory
is the destination directory pathname for copy mode.
file
is a pathname of a file to be copied or archived.
Modes
``list mode''-
When neither -r nor -w are specified,
pax writes
the names of the members of the archive file read from the standard input,
with pathnames matching the specified patterns, to standard output.
If a named file is of type directory,
the file hierarchy rooted at the file is written out as well.
``read mode''-
When -r is specified and -w is not,
pax
extracts the members of the archive file read from the standard input,
with pathnames matching the specified patterns.
If an extracted file is of type directory,
the file hierarchy rooted at that file is extracted as well.
The extracted file is created relative to the current file hierarchy.
``write mode''-
When -w is specified and -r is not,
pax
writes the contents of the file operands
to the standard output in an archive format.
If no
file
operands are specified, a list of files to copy, one per line,
is read from the standard input.
A file of type directory includes all of the files
in the file hierarchy rooted at the file.
``copy mode''-
When both -r and -w are specified,
pax
copies the file operands to the destination directory.
If no
file
operands are specified, a list of files to copy, one per line,
is read from the standard input.
A file of type directory includes all files in the file hierarchy
rooted at the file.
The effect of the copy is as if the copied files were written to an
archive file and then extracted, except that there may be hard links
between the original and the copied files.
If the destination directory is a subdirectory of one of the files
to be copied, the results are unspecified.
It is an error for the file named by the directory operand not to exist,
not be writable by the user, or not be a file of type directory.
In read or copy modes,
if intermediate directories are necessary to extract an archive member,
pax
performs actions equivalent to the
mkdir(2)
function, called with the following arguments:
-
the intermediate directory used as the
path argument.
-
the value of the bitwise inclusive OR
of S_IRWXU, S_IRWXG and S_IRWXO
as the mode argument.
The supported archive formats are automatically detected on input.
A single archive can span multiple files.
If any specified
pattern
or
file
operands are not matched by at least one file or archive member,
pax
writes a diagnostic message to standard error for each one
that did not match and exits with a non-zero exit status.
Options
The following options are supported:
-r-
Read an archive file from standard input.
-w-
Write files to the standard output in the specified archive format.
-a-
Append files to the end of the archive.
-b blocksize-
Block the output at a positive decimal integer number of bytes
per write to the archive file.
Blocking is automatically determined on input.
Portable applications must not specify a
blocksize
value larger than 32256.
Use the
-x
option to specify the output archive format.
-c-
Match all file or archive members except those specified by the
pattern
or
file
operands.
-d-
Cause files of type directory being copied or archived or
archive members of type directory being extracted to match
only the file or archive member itself and not the file hierarchy
rooted at the file.
-f archive-
Specify the pathname of the input or output archive,
overriding the default standard input or standard output.
-i-
Interactively rename files or archive members.
For each archive member matching a
pattern
operand or file matching a
file
operand, a prompt is written to the file
/dev/tty.
The prompt contains the name of the file or archive member,
but the format is otherwise unspecified.
A line is then read 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 line.
The
pax
utility immediately exits with a non-zero exit status if end-of-file
is encountered when reading a response or if
/dev/tty
cannot be opened for reading and writing.
-k-
Prevents the overwriting of existing files.
-l-
Link files.
In copy mode, hard links are made between the source and
destination file hierarchies whenever possible.
-n-
Select the first archive member that matches each
pattern
operand.
No more than one archive member is matched for each pattern.
-p string-
Specify one or more file characteristic options or privileges.
The
string
argument must be a string specifying file characteristics
to be retained or discarded on extraction.
The string consists of the specification characters
a,
e,
m,
o,
and
p.
Other characters can be included.
Multiple characteristics can be concatenated within the same string
and multiple
-p
options can be specified.
The meaning of the specification characters are:
a-
Do not preserve file access time.
e-
Preserve the user ID, group ID, file mode bits, access time,
modification time and other file characteristics.
m-
Do not preserve file modification times.
o-
Preserve the user ID and group ID.
p-
Preserve the file mode bits.
If neither
e
nor
o
is specified, or the user ID and group ID
are not preserved for any reason,
pax
does not set the S_ISUID and S_ISGID bits of the file mode.
If the preservation of any of these items fails for any reason,
pax
writes a diagnostic message to standard error.
Failure to preserve these items affects the final exit status,
but does not cause the extracted file to be deleted.
If file-characteristic letters in any of the
string
arguments are duplicated or conflict with each other,
the ones given last take precedence.
For example, if
-p eme
is specified, file modification times will be preserved.
-e replstr-
Modify file or archive member names named by
pattern
or
file
operands according to the substitution expression
replstr,
using the syntax of the
ed
utility.
Any non-null character can be used as a delimiter.
Multiple
-s
expressions can be specified; the expressions are applied
in the sequence specified,
terminating with the first successful substitution.
The optional trailing
g
is as defined in the
ed
utility.
The optional trailing
p
causes successful substitutions to be written to standard error.
File or archive member names that substitute to the empty string
are ignored when reading and writing archives.
-t-
Cause the access times of the archived files to be the same
as they were before being read by
pax.
-u-
Ignore files that have a less recent file modification time
than a pre-existing file or archive member with the same name.
In read mode, an archive member with the same name as a file in
the file system is extracted if the archive member is newer than the file.
In write mode, an archive file member with the same name as a
file in the file system is superseded if the file is newer
than the archive member.
It is unspecified if this is accomplished by actual replacement
in the archive or by appending to the archive.
In copy mode, 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-
In list mode, produce a verbose table of contents.
Otherwise, write archive member pathnames to standard error.
-x format-
Specify the output archive format.
The
pax
utility recognizes the following formats:
cpio-
The extended
cpio
interchange format;
see
cpio(1).
The default
blocksize
for this format for character special archive
files is 5120.
Implementations support all
blocksize
values less than or equal to 32256 that are multiples of 512.
ustar-
The extended
tar
interchange format; see
tar(1).
The default
blocksize
for this format for character special archive files is 10240.
Implementations support all
blocksize
values less than or equal to 32256 that are multiples of 512.
The pax command has been updated so that, when the
ustar format is specified, it will handle files
larger than 2GB.
Any attempt to append to an archive file in a format different
from the existing archive format causes
pax
to exit immediately with a non-zero exit status.
-X-
When traversing the file hierarchy specified by a pathname,
pax
does not descend into directories that have a different device
ID.
-y-
An old option equivalent to the -i option
with a single period and an empty line.
The options that operate on the names of files or archive members
(-c, -i, -n, -s, -u, and -v)
interact.
In read mode, the archive members are selected based on the
user-specified
pattern
operands as modified by the
-c,
-n,
and
-u
options.
Then, any
-s
and
-i
options modify, in that sequence, the names of the selected files.
The
-v
option writes names resulting from these modifications.
In write mode, the files are selected based on the user-specified
pathnames as modified by the
-n
and
-u
options.
Then, any
-s
and
-i
options, in that sequence, modify the names of these selected files.
The
-v
option writes names resulting from these modifications.
If both the
-u
and
-v
options are specified,
pax
does not consider a file selected unless it is newer than the file
to which it is compared.
Environment variables
The following environment variables affect the execution of
pax:
LANG-
Provide a default value for the internationalization variables
that are unset or null.
If
LANG
is unset or null,
the corresponding value from the default locale is used.
If any of the internationalization variables contains an invalid setting,
the utility behaves as if none of the variables had been defined.
LC_ALL-
If set to a non-empty string value,
overrides the values of all the other internationalization variables.
LC_COLLATE-
Determine the locale for the behavior of ranges,
equivalence classes and multi-character collating elements
used in the pattern matching expressions for the
pattern
operand, the basic regular expression for the
-s
option, and the extended regular expression defined for the
``yesexpr''
locale keyword in the
LC_MESSAGES
category.
LC_CTYPE-
Determine the locale for the interpretation of sequences of bytes
of text data as characters (for example,
single- as opposed to multi-byte characters in arguments and input files),
the behavior of character classes used in the extended regular expression
defined for the
``yesexpr''
locale keyword in the
LC_MESSAGES
category, and pattern matching.
LC_MESSAGES-
Determine the locale for the processing of affirmative responses
that should be used to affect the format and content
of diagnostic messages written to standard error.
LC_TIME-
Determine the format and contents of date and time strings when the
-v
option is specified.
Consequences of errors
If
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 status is returned,
but processing continues.
In the case where
pax
cannot create a link to a file,
pax
does not, by default, 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 the file or (if the
-n
option was not specified) may have extracted a file of the same name
as that specified by the user, but which is not the file the user
wanted.
Additionally, the file modes of extracted directories may have
additional bits from the S_IRWXU mask set
as well as incorrect modification and access times.
References
cpio(1),
mkdir(2),
tar(1)
Notices
The
-p
(privileges) option is used to reconcile differences between
historical
tar
and
cpio
implementations.
In particular, the two utilities use
-m
in different ways.
The
-p
option provides a consistent means of extending the ways
in which future file attributes can be addressed,
such as for enhanced security systems or high-performance files.
Although it may seem complex,
there are really two modes that are most commonly used:
-p e-
Preserve everything.
This would be used by the historical superuser, someone with all
the appropriate privileges, to preserve all aspects of the files
as they are recorded in the archive.
The
e
flag is the sum of
o
and
p
attributes.
-p p-
Preserve the file mode bits.
This would be used by the user with regular privileges
who wished to preserve aspects of the file other than the ownership.
The file times are preserved by default,
but two other flags are offered to disable these
and use the time of extraction.
The one pathname per line format of standard input precludes
pathnames containing newline characters.
Although such pathnames violate the portable filename guidelines,
they may exist and their presence may inhibit usage of
pax
within shell scripts.
This problem is inherited form historical archive programs.
The problem can be avoided by listing filename arguments
on the command line instead of on standard input.
The
pax(1)
utility supports the archival of files larger than
2 Gigabytes (2GB) in size when using the default ``ustar'' forma
t.
Files up to 2^63-1 bytes in size are supported.
The pax utility also supports filenames and
symbolic link filenames up to 1024 characters long when using
the default ``ustar'' format.
Older versions of pax will not be able to extract
files larger than 2GB in size, or files whose
filenames or symbolic link names are larger than 255 characters long.
Examples
The following command:
pax -w -f /dev/rmt/1m
copies the contents of the current directory to tape drive 1,
medium density.
The following commands:
mkdir newdir
pax -rw olddir newdir
copy the
olddir
directory hierarchy to
newdir.
pax -r -s ',^//*usr//*,,' -f a.pax
reads the archive
a.pax,
with all files rooted in /usr in the archive extracted
relative to the current directory.
© 2005 The SCO Group, Inc. All rights reserved.
SCO OpenServer Release 6.0.0 - 02 June 2005