pax(1) General Commands Manual pax(1)
pax - Extracts, writes, and lists archive files
Listing Member Files of Archived Files
pax [-cdnv] [-f archive] [-s replacement_string]... [pattern...]
Extracting Archive Files
pax -r [-cdiknuvyz] [-f archive] [-p string]... [-s replacement_string]... [pattern...]
Writing Archive Files
pax -w [-adituvVXy] [-b blocksize] [-f archive] [-s replacement_string]... [-x format] [file...]
pax -r -w [-diklntuvVXy] [-p string]... [-s replacement_string]... [file...] directory
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 posi-
tive 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 modi-
fication 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
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
In the ed command, old is a basic regular expression and new can contain an & (ampersand),
(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 sub-
stitution. 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 ar-
chive 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 the file.
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 imme-
diately 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. Substitu-
tions 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
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 user-specified pattern argu-
ments 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
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 mem-
bers in the archive.
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
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
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
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
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
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 ar-
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.
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/rmt0 . 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 tar format.
The following pairs of commands demonstrate conversions from cpio and tar to pax. In all cases, the examples show comparable com-
mand-line usage rather than identical output formats. The -x option can be specified to the pax commands shown here, producing ar-
chives 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
(cd /fromdir;find . -print) | cpio -pdlum /todir pax -rw /fromdir /todir
tar cf archive * pax -w -f archive *
tar xfv - < archive pax -rv < archive
(cd /fromdir; tar cf - . ) | (cd /todir; tar xpf -) pax -rw /fromdir /todir
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 vari-
ables 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)