pax - Extracts, writes, and lists archive files
Listing Member Files of Archived Files
pax [-cdnv] [-f archive] [-s replacement_string]... [pattern...]
Extracting Archive Files [Toc] [Back]
pax -r [-cdiknuvyz] [-f archive] [-p string]... [-s
Writing Archive Files [Toc] [Back]
pax -w [-adituvVXy] [-b blocksize] [-f archive] [-s
replacement_string]... [-x format] [file...]
Copying Files [Toc] [Back]
pax -r -w [-diklntuvVXy] [-p string]... [-s replacement_string]...
The pax command extracts, writes, and lists members of
archive files. It also copies files and directory hierarchies.
Interfaces documented on this reference page conform to
industry standards as follows:
Refer to the standards(5) reference page for more information
about industry standards and associated tags.
Appends files to the end of the archive. Certain devices
might not support appending. Specifies the block size for
output to be the positive decimal integer of bytes specified
by the blocksize argument. The block size value cannot
exceed 32,256, the maximum size for POSIX portability.
Blocking is automatically determined on input. Matches
all file or archive members except those specified by the
pattern or file arguments. Causes directories being
copied or archived, or archived directories being
extracted, to match only the directory or archived directory
itself and not the contents of the directory or
archived directory. Specifies the path of an archive file
to be used instead of standard input (when the -w option
is not specified) or the standard output (when the -w
option is specified but the -r option is not). When specified
with the -a option, any files written to the archive
are appended to the end of the archive. Interactively
renames files or archives interactively. For each archive
member that matches the pattern argument or file that
matches a file argument, a prompt is written to the terminal
(/dev/tty) that contains the name of a file or archive
member. A line is then read from the terminal. If this
line is empty, the file or archive member is skipped. If
this line consists of a dot, 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
command immediately exits with a nonzero exit status if an
End-of-File is encountered when reading a response or if
it cannot read or write to the terminal. Prevents the pax
command from writing over existing files. Links files
when copying files. When both -r and -w are specified,
hard links are established between the source and destination
file hierarchies whenever possible. Selects the
first archive member that matches each pattern argument.
No more than one archive member is matched for each pattern
(although members of type directory will still match
the file hierarchy rooted at that file). Specifies one or
more file characteristics to be retained or discarded on
extraction. The string argument consists of the characters
a, e, m, o, and p. Multiple characteristics can be concatenated
within the same string and multiple -p options
can be specified. The specification flags have the following
meanings: Does not retain file-access times.
Retains the user ID, group ID, access permission, access
time, and modification time. Does not retain file-modification
times. Retains the user ID and the group ID.
Retains the access permission.
Retain means that an attribute stored in the
archive is given to the extracted file, subject to
the permissions of the invoking process; otherwise,
the attribute is determined as part of the normal
file creation action.
If neither the e nor the o flag is specified, or
the user ID and group ID are not retained, the pax
command does not set the S_ISUID and S_ISGID bits
of the access permission. If the retention of any
of these items fails, the pax command writes a
diagnostic message to standard error. Failure to
retain any of the items affects the exit status,
but does not cause the extracted file to be
deleted. If specification flags are duplicated or
conflict with each other, the ones given last take
precedence. For example, if -p eme is specified,
file-modification times are retained. Reads an
archive file and any associated extended attributes
from the standard input. Modifies file-member or
archive-member names specified by the pattern or
file arguments according to the substitution
expression replacement_string, using the syntax of
the ed command. The substitution expression has the
following format: -s /old/new/ [gp]
In the ed command, old is a basic regular expression
and new can contain an & (ampersand), \n (n is
a digit) back references, or subexpression matching.
The old string can also contain newline characters.
Any nonnull character can be used as a delimiter.
The slash (/) character is the delimiter in the
previous format). Multiple -s option expressions
can be specified; the expressions are applied in
the order specified, terminating with the first
successful substitution. The optional trailing g
character performs as in the ed command. The
optional trailing p character causes successful
substitutions to be written to the standard error.
File-member or archive-member names that substitute
to the empty string are ignored when reading and
writing archives. Causes the access times of the
archived files to be the same as they were before
being read by the pax command. Ignores files that
are older (having a less recent file modification
time) than a preexisting file or archive member
with the same name.
When extracting files (-r option), an archive member
with the same name as a file in the file system
is extracted if the archive member is newer than
When writing files to an archive file (-w option),
an archive member with the same name as a file in
the file system is superseded if the file is newer
than the archive member.
When copying files to a destination directory (-rw
options), 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. Writes
information about the process. If neither the -r or
-w options are specified, the -v option produces a
verbose table of contents that resembles the output
of ls -l; otherwise, archive-member pathnames are
written to standard error. [Tru64 UNIX] Prevents
any extended attributes from being archived with
associated files. This option is particularly useful
for archiving files that are to be restored
with previous versions of tar and cpio. [Tru64
UNIX] Writes files and any extended attributes to
the standard output in the specified archive format.
Specifies the output archive format. The pax
command recognizes the following formats: Extended
cpio interchange format. The default blocking value
for this format for character special archive files
is 5120. Blocking values from 512 to 32,256 in
increments of 512 are supported. Extended tar
interchange format. The default blocking value for
this format for character special archive files is
10240. Blocking values from 512 to 32,256 in
increments of 512 are supported. This option lets
the user archive long file names and extended
UID/GID values. Extended tar interchange format.
This is the default output archive format. The
default blocking value for this format for character
special archive files is 10240. Blocking values
from 512 to 32,256 in increments of 512 are supported.
Any attempt to append to an archive file in a format
different from the existing archive format
causes the pax command to exit immediately with a
nonzero exit status. When traversing the file
hierarchy specified by a pathname, the pax command
does not descend into directories that have a different
device ID. [Tru64 UNIX] Prompts interactively
for the disposition of each file. Substitutions
specified by the -s option are performed
before you are prompted for disposition. An EOF
marker or an input line starting with the character
"q" causes the pax command to exit. Otherwise, an
input line starting with anything other than the
character "y" causes the file to be ignored.
[Tru64 UNIX] Positions the tape after the EOF
marker on extraction or listing. The z option lets
the user extract or list tapes that have multiple
archives on them one after the other without error
as a result of the tape not being positioned correctly
for the next extraction or listing.
Option Interaction and Processing Order [Toc] [Back]
The options that operate on the names of files or archive
members (-c, -i, -n, -s, -u, and -v) interact as follows.
When extracting files (-r option), archive members are
selected, using the modified names, according to the userspecified
pattern arguments as modified by the -c, -n, and
-u options. Then, any -s and -i options modify, in that
order, the names of the selected files. The -v option
writes the names resulting from these modifications.
When writing files to an archive file (-w option), or when
copying files, the files are selected according to the
user-specified pathnames as modified by the -n and -u
options. Then, any -s and -i options modify, in that
order, the names resulting from these modifications. The
-v option writes the names resulting from these modifications.
If both the -u and -n options are specified, the pax command
does not consider a file selected unless it is newer
than the file to which it is compared.
The destination directory pathname for copy mode. A pathname
of a file to be copied or archived. A pattern matching
one or more pathnames of archive members. A pattern
must be given in name-generating notation. The default, if
no pattern is specified, is to select all members in the
The pax command extracts and writes member files and any
associated, extended attributes of archive files; writes
lists of the member files of archives; and copies directory
hierarchies. The -r and -w options specify the
archive operation performed by the pax command.
The pattern argument specifies a pattern that matches one
or more paths of archive members. A \ (backslash) character
is not recognized in the pattern argument and it prevents
the subsequent character from having any special
meaning. If no pattern argument is specified, all members
are selected in the archive.
If a pattern argument is specified, but no archive members
are found that match the pattern specified, the pax command
detects the error, exits with a nonzero exit status,
and writes a diagnostic message.
The pax command can read both tar and cpio archives. In
the case of cpio, this means that pax can read ASCII
archives (which are created with cpio -c) and binary
archives (which are created without the -c option). The
supported archive formats are automatically detected on
The pax command can also write archives that tar and cpio
can read; by default, pax writes archives in the ustar
extended tar interchange format. The pax command also
writes ASCII cpio archives; use the -x cpio option to
specify this extended cpio output format.
Listing Member Files of Archived Files [Toc] [Back]
When neither the -r nor the -w options are specified, the
pax command writes the names of the members of the archive
file read from the standard input, with pathnames matching
the specified patterns, to the standard output. If a named
file is a directory, the file hierarchy contained in the
directory is also written. You can specify the pax command
without the -r or -w options with the -c, -d, -f, -n,
-s, and -v options, and with the pattern argument.
If neither the -r or -w options are included, pax lists
the contents of the specified archive, one file per line.
The pax command lists hard link pathnames as follows:
pathname == linkname
The pax command lists symbolic link pathnames as follows:
pathname -> linkname
In both of the preceding cases, pathname is the name of
the file that is being extracted, and linkname is the name
of a file that appeared earlier in the archive.
If the -v option is specified, the listing of hard link
pathnames is output in the ls -l command format.
Extracting Archive Files [Toc] [Back]
When the -r option is specified, but the -w option is not,
the pax command extracts the members of an archive file
and any extended attributes read from the standard input,
and with pathnames matching the pattern argument if one is
specified. If an extracted file is a directory, the file
hierarchy contained in the directory is also extracted.
The extracted files are created relative to the current
file hierarchy. The -r option can be specified with the
-c, -d, -f, -n, -s, and -v options, and a pattern argument.
The access and modification times of the extracted files
are the same as the archived files. The access permissions
of the extracted files remain as archived unless affected
by the user's default file creation mode. The S_ISUID and
S_ISGID bits of the extracted files are cleared.
If intermediate directories are necessary to extract an
archive member, the pax command creates the directories
with access permissions set as the bitwise inclusive OR of
the values of the S_IRWXU, S_IRWXG, and S_IRWXO options.
If the selected archive format supports the specification
of linked files (both the tar and cpio formats do), it is
an error if these files cannot be linked when the archive
is extracted. The pax command informs you of the error
and continues processing.
Writing Archive Files [Toc] [Back]
When the -w option is specified and the -r option is not,
the pax command writes the contents of the files and any
extended attributes specified by the file arguments to the
standard output in an archive format. If no file arguments
are specified, a list of files to copy, one per line, is
read from the standard input. When the file argument specifies
a directory, all of the files and any extended
attributes contained in the directory are written. The -w
option can be specified with the -b, -d, -f, -i, -s, -t,
-u, -v, -x, and -X options and with file arguments.
If -w is specified, but no files are specified, standard
input is used. If neither -f or -w are specified, standard
input must be an archive file.
Copying Files [Toc] [Back]
When both the -r and -w options are specified, the pax
command copies the files and any extended attributes specified
by the file arguments to the destination directory
specified by the directory argument. If no file arguments
are specified, a list of files to copy, one per line, is
read from the standard input. If a specified file is a
directory, the file hierarchy contained in the directory
is also copied. The -r and -w options can be specified
with the -d, -i, -k, -l, -p, -n, -s, -t, -u, -v, and -X
options and with the file arguments. A directory argument
must be specified.
Copied files are the same as if they were written to an
archive file and subsequently extracted.
[Tru64 UNIX] When you use the -i option (interactively
renames files) on files to which there are hard links, pax
does not create hard links to the renamed files. [Tru64
UNIX] Archives created with the new pax utility and having
cpio format can be restored using only the new pax or
cpio commands even if none of the archived files have
extended attributes. [Tru64 UNIX] To achieve backward
compatibility of archived files, invoke the -V option to
disable the archiving of extended attributes altogether.
[Tru64 UNIX] Socket files are ignored while archiving
through the pax command.
The following exit values are returned: Successful completion.
An error occurred.
To copy the contents of the current directory to the tape
drive, enter: pax -w -f /dev/tape0_d0 . To copy the olddir
directory hierarchy to newdir, enter: mkdir newdir (cd
./olddir ; pax -p e -rw . ../newdir) To read the archive
a.pax, with all files rooted in the directory /usr in the
archive extracted relative to the current directory,
enter: pax -r -s ',^//*usr//*,,' -f a.pax
All of the preceding examples create archives in
The following pairs of commands demonstrate conversions
from cpio and tar to pax. In all cases, the
examples show comparable command-line usage rather
than identical output formats. The -x option can
be specified to the pax commands shown here, producing
archives to select specific output formats:
ls * | cpio -ocv pax -wdv *
find /mydir -type f -print | cpio -oc find /mydir
-type f -print | pax -w
cpio -icdum < archive pax -r < archive
(find fromdir -print) | cpio -pdlum todir pax -rwl
tar cf archive * pax -w -f archive *
tar xfv - < archive pax -rv < archive
(cd fromdir; tar cf - . ) | (cd todir; tar xpf -)
pax -rw -p e fromdir todir
ENVIRONMENT VARIABLES [Toc] [Back]
The following environment variables affect the execution
of pax: Provides 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 contain
an invalid setting, the utility behaves as if none of the
variables had been defined. If set to a non-empty string
value, overrides the values of all the other internationalization
variables. Determines the locale for the interpretation
of sequences of bytes of text data as characters
(for example, single-byte as opposed to multibyte characters
in arguments and input files), the behavior of character
classes used in the extended regular expressions
defined for the yesexpr locale keyword in the LC_MESSAGES
category, and pattern matching. Determines the locale for
the format and contents of diagnostic messages written to
standard error. Determines the location of message catalogues
for the processing of LC_MESSAGES.
Commands: cpio(1), ed(1), tar(1)
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