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NAME

pax — Extracts, writes, and lists archive files; copies files and directory hierarchies

SYNOPSIS

Listing Member Files of Archived Files

pax [-cdnv] [-f archive] [-s replstr ] ... [pattern ...]

Extracting Archive Files

pax -r [-cdiknuvy] [-f archive] [-p string ] ... [-s replstr ] ... [pattern ...]

Writing Archive Files

pax -w [-adituvXy] [-b blocking] [-f archive] [-s replstr ] ... [-x format] [file ...]

Copying Files

pax -r -w [-diklntuvXy] [-p string ] ... [-s replstr ] ... [file ...] directory

DESCRIPTION

The pax command extracts and writes member files of archive files; writes lists of the member files of archives; and copies directory hierarchies. The -r and -w flags 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 flag). The supported archive formats are automatically detected on input.

pax can also write archives that tar and cpio can read; by default, pax writes archives in the ustar extended tar interchange format. pax also writes ASCII cpio archives; use the -x cpio flag to specify this extended cpio output format.

Options

-a

Appends files to the end of the archive. Certain devices might not support appending.

-b blocking

Specifies the block size for output to be the positive decimal integer of bytes specified by the blocking argument. The block size value cannot exceed 32,256. Blocking is automatically determined on input.

Do not specify a value for the blocking argument larger than 32768. Default blocking when creating archives depends on the archive format. (See the -x flag description.)

-c

Matches all file or archive members except those specified by the pattern or file arguments.

-d

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.

-f archive

Specifies the path of an archive file to be used instead of standard input (when the -w flag is not specified) or the standard output (when the -w flag is specified but the -r flag is not). When specified with the -a flag, any files written to the archive are appended to the end of the archive.

-i

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.

-k

Prevents the pax command from writing over existing files.

-l

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.

-n

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).

-p string

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 flags can be specified. The specification flags have the following meanings:

a

Does not retain file-access times.

e

Retains the user ID, group ID, access permission, access time, and modification time.

m

Does not retain file-modification times.

o

Retains the user ID and the group ID.

p

Retains the access permission.

Note that "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.

-r

Reads an archive file from the standard input.

-s

Modifies file-member or archive-member names specified by the pattern or file arguments according to the substitution expression replstr, using the syntax of the ed command. The substitution expression has the following format:

-s/old/new/[gp]

where as 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 flag 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.

-t

Causes the access times of the archived files to be the same as they were before being read by the pax command.

-u

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 flag), 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 flag), 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 flags), 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

Writes information about the process. If neither the -r or -w flags are specified, the -v flag produces a verbose table of contents that resembles the output of ls -l; otherwise, archive-member pathnames are written to standard error.

-w

Writes files to the standard output in the specified archive format.

-x format

Specifies the output archive format. The pax command recognizes the following formats:

cpio

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.

ustar

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.

-X

When traversing the file hierarchy specified by a pathname, the pax command does not descend into directories that have a different device ID.

-y

Prompts interactively for the disposition of each file. Substitutions specified by -s flags are performed before you are prompted for disposition. An EOF marker or an input line starting with the character q causes pax to exit. Otherwise, an input line starting with anything other than y causes the file to be ignored. This flag cannot be used in conjunction with the -i flag.

Option Interaction and Processing Order

The flags that operate on the names of files or archive members (-c, -i, -n, -s, -u, and -v) interact as follows.

When extracting files (-r flag), archive members are selected, using the modified names, according to the user-specified pattern arguments as modified by the -c, -n, and -u flags. Then, any -s and -i flags modify, in that order, the names of the selected files. The -v flag writes the names resulting from these modifications.

When writing files to an archive file (-w flag), or when copying files, the files are selected according to the user-specified pathnames as modified by the -n and -u flags. Then, any -s and -i flags modify, in that order, the names resulting from these modifications. The -v flag writes the names resulting from these modifications.

If both the -u and -n flags are specified, the pax command does not consider a file selected unless it is newer than the file to which it is compared.

Listing Member Files of Archived Files

When neither the -r nor the -w flags 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 flags with the -c, -d, -f, -n, -s, and -v flags, and with the pattern argument.

If neither the -r or -w flags are included, pax lists the contents of the specified archive, one file per line. pax lists hard link pathnames as follows:

pathname==linkname

pax 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 flag is specified, the listing of hard link pathnames is output in the ls -l command format.

Extracting Archive Files

When the -r flag is specified, but the -w flag is not, the pax command extracts the members of an archive file 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 flag can be specified with the -c, -d, -f, -n, -s, and -v flags, 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. pax informs you of the error and continues processing.

Writing Archive Files

When the -w flag is specified and the -r flag is not, the pax command writes the contents of the files 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 contained in the directory are written. The -w flag can be specified with the -b, -d, -f, -i, -s, -t, -u, -v, -x, and -X flags 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

When both the -r and -w flags are specified, the pax command copies the files 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 flags can be specified with the -d, -i, -k, -l, -p, -n, -s, -t, -u, -v, and -X flags 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, except that there may be hard links between the original and the copied files.

RETURN VALUE

The pax command returns a value of 0 (zero) if all files were successfully processed; otherwise, pax returns a value greater than 0 (zero).

EXAMPLES

To copy the contents of the current directory to the tape drive, enter:

pax -w -f /dev/rmt/0m .

To copy the olddir directory hierarchy to newdir enter:

mkdir newdir cd olddir pax -rw olddir 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 command-line usage rather than identical output formats. The -x flag 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 (cd /fromdir;find . -print) | cpio -pdlum /todir pax -rwl /fromdir /todir tar cf archive * pax -w -f archive * tar xfv - < archive pax -rv < archive (cd /fromdir; tar cf - . ) | (cd /todir; tar xf -) pax -rw /fromdir /todir

Notes

When you use the -i flag (interactively renames files) on files to which there are hard links, pax does not create hard links to the renamed files.

WARNINGS

Because of industry standards and interoperability goals, pax does not support the archival of files larger than 2GB or files that have user/group IDs greater than 60K. Files with user/group IDs greater than 60K are archived and restored under the user/group ID of the current process.

AUTHOR

pax was developed by Mark H. Colburn, OSF, and HP.

SEE ALSO

ed(1), tar(4).

STANDARDS CONFORMANCE

pax: XPG4, POSIX.2

This implementation of pax is based upon a POSIX.2 draft specification. HP intends to update pax to meet the final POSIX.2 Standard once it completes, and thus the pax implementation is likely to change in a future release of HP-UX, possibly in ways incompatible with the current implementation. HP recommends using the current implementation only if absolutely necessary.



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