pax Command

Purpose

Extracts, writes, and lists members of archive files; copies files and directory hierarchies.

Syntax

To List Member Files of Archived Files

pax [  -c | -n] [-d] [-U ] [  -v] [  -H |  -L ] [-f  Archive] [  -s ReplacementString... ] [-x Format] [-o Options] [ -Z ] [Pattern... ]

To Extract Archive Files Using the -r Flag

pax -r [  -c  | -n ] [  -d ] [  -i ] [  -k ] [ -U ] [  -u ] [  -v ] [  -H |  -L ] [  -f Archive] [  -o Options] [  -p String... ] [  -s ReplacementString... ] [  -x Format] [ -Z ]  [Pattern ... ]

To Write Archive Files Using the -w Flag

pax -w [  -d ] [  -i ] [  -t ] [ -U ] [  -u ] [  -v ] [  -X ] [  -H |   -L ] [ -E ] [  -b Blocking] [[ -a ]   -f Archive] [  -o Options] [  -s ReplacementString... ] [  -x Format] [ -Z ] [ File... ]

To Copy Files Using the -r and -w Flags

pax -r -w [  -d ] [  -i ] [  -k ] [  -l ] [  -t ] [ -U ] [  -u ] [  -v ] [  -X ] [  -H |   -L ] [  -p String... ] [  -o Options] [  -s ReplacementString... ] [  -x Format] [ -Z ] [File ... ] Directory

Description

Listing Member Files of Archived Files (List Mode)

When the -r flag or the -w flag is not specified, the pax command lists all the member files of the archive file that is read from standard input. If the Pattern parameter is specified, only the member files with path names that match the specified patterns are written to standard output. If a named file is a directory, the file hierarchy that is contained in the directory is also written. When the -r flag or the -w flag is not specified, the -c, -d, -f, -n, -s, and -v flags, and the Pattern parameter can be specified.

Extracting Archive Files Using the -r Flag (Read Mode)

When the -r flag is specified, but the -w flag is not, the pax command extracts all the member files of the archive files that are read from standard input. If the Pattern parameter is specified, only the member files with path names that match the specified patterns are written to standard output. If a named file is a directory, the file hierarchy that is contained in the directory is also extracted. The -r flag can be specified with the -c, -d, -f, -i, -k, -n, -s, -u, and -v flags, and with the Pattern parameter.

The access and modification times of the extracted files are the same as the archived files. The file modes of the extracted files are the same as when they were archived, unless they are affected by the user's default file creation mode (umask). 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 masks.

If the selected archive format supports the specification of linked files, it is an error if these files cannot be linked when the archive is extracted.

Writing Archive Files Using the -w Flag (Write Mode)

When the -w flag is specified and the -r flag is not, the pax command writes the contents of the files that are specified by the File parameter to standard output in an archive format. If no File parameter is specified, a list of files to copy, one per line, is read from the standard input. When the File parameter specifies a directory, all of the files that are contained in the directory are written. The -w flag can be specified with the -a, -b, -d, -f, -i, -o, -s, -t, -u, -v, -x, and -X flags and with File parameters.

Copying Files Using the -r and -w Flags (Copy Mode)

When both the -r and -w flags are specified, the pax command copies the files that are specified by the File parameters to the destination directory specified by the Directory parameter. If no files 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 that is contained in the directory is also copied. The -r and -w flags can be specified with the -d, -i, -k, -l, -o, -p, -s, -t, -u, -v, and -X flags and with File parameters. The Directory parameter must be specified.

Copied files are the same as written to an archive file and are later extracted, except that there are hard links between the original and the copied files.

Modifying the Archive Algorithm Using the -o Flag

Use the -o flag to modify the archive algorithm according to keyword-value pairs. The keyword-value pairs must adhere to a correct archive format. A list of valid keywords and their behavior is given in the subsequent description of the -o flag.

Further Notes

In read or copy modes, if intermediate directories are necessary to extract an archive member, the pax command does actions similar to the mkdir() subroutine with the intermediate directory used as the path argument and the value S_IRWXU as the mode argument.

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 an error status.

In traversing directories, the pax command detects the infinite loops by entering a previously visited directory that is an ancestor of the last file visited. Upon detection of an infinite loop, the pax command writes a diagnostic message to standard error and terminates.

When pax command is in read mode or list mode, by using the -x pax archive format, a file name, link name, owner name, or any other field in an extended header record cannot be translated from the pax UTF8 code set format to the current code set and locale. The pax command writes a diagnostic message to standard error, processes the file as described for the -o invalid= option, and then processes the next file in the archive.

For AIX® 5.3, the pax command ignores the extended attributes by default. The -U option informs pax to archive or restore extended attributes, which include ACLs. The -pe option preserves ACLs. When the -pe option is specified and if pax fails to preserve the ACLs, a diagnostic message is written to the standard error but the extracted file is not deleted. A non-zero exit code is returned. A new record type is required for extended attribute entries in the pax archive files.

Variables

Flags

Extended header keywords

(Applicable only to the -x pax format.)

If the -x pax format is specified, the keywords and values that are defined in the list below can be used as parameters to the -o flag, in either of two modes:

keyword=value

When used in write or copy mode, these keyword-value pairs are written into the global extended header records of the new archive. When used in read or list mode, these keyword-value pairs act as if they were present in the global extended header records of the archive that is being read. In both cases, the given value is applied to all files that do not have a value that is assigned in their individual extended header records for the specified keyword.

keyword:=value

When used in write or copy mode, these keyword-value pairs are written into the extended header records of each file in the new archive. When used in read or list mode, these keyword-value pairs act as if they were present in the extended header records of each file in the archive that is being read. In both cases, the given value overrides any value for the specified keyword that is found in global or file-specific extended header records.

atime

The file access time for the following files, equivalent to the value of the st_atime member of the stat structure for a file.

charset

The name of the character is set to encode the data in the following files. The entries in this table are defined to refer to known standards:

The encoding is included in an extended header for information only; when pax is used as described, it does not translate the file data into any other encoding. The BINARY entry indicates binary data that is not encoded.

comment

A series of characters used as a comment. All characters in the value field are ignored by pax.

ctime

The file creation time for the following file(s), equivalent to the value of the st_ctime member of the stat structure for a file.

gid

The group ID of the group that owns the file, expressed as a decimal number by using digits from ISO/IEC 646. This record overrides the gid field in the following header block(s). When used in write or copy mode, pax includes a gid extended header record for each file whose group ID is greater than 99,999,999.

gname

The group of the following file(s), formatted as a group name in the group database. This record overrides the gid and gname fields in the following header blocks, and any gid extended header record. When used in read, copy, or list mode, pax translates the name from the UTF8 encoding in the header record to the character set appropriate for the group database on the receiving system. If any of the UTF8 characters cannot be translated, and if the -o invalid=UTF8 option is not specified, the results are undefined. When used in write or copy mode, pax includes a gname extended header record for each file whose group name cannot be represented entirely with the letters and digits of the portable character set.

linkpath

The path name of a link that is created to another file, of any type, previously archived. This record overrides the linkname field in the following ustar header block(s).

The following ustar header block determines the type of link that is created, whether hard or symbolic. In the latter case, the linkpath value is the contents of the symbolic link. pax translates the name of the link (contents of the symbolic link) from the UTF8 encoding to the character set appropriate for the local file system.

When used in write or copy mode, pax includes a link path extended header record for each link whose path name cannot be represented entirely with the members of the portable character set other than NULL.

mtime

The file modification time of the following file(s), equivalent to the value of the st_mtime member of the stat structure for a file. This record overrides the mtime field in the following header block(s). The modification time is restored if the process has the appropriate privilege to do so.

path

The pathname of the following file(s). This record overrides the name and prefix fields in the following header block(s). pax translates the path name of the file from the UTF8 encoding to the character set appropriate for the local file system. When used in write or copy mode, pax includes a path extended header record for each file whose path name cannot be represented entirely with the members of the portable character set other than NULL.

realtime.any

The keywords that are prefixed by real time are reserved for future POSIX real-time standardization. pax recognizes but silently ignores them.

security.any

The keywords that are prefixed by security are reserved for future POSIX security standardization. pax recognizes but silently ignores them.

size

The size of the file in octets, expressed as a decimal number using digits from ISO/IEC 646. This record overrides the size field in the following header block(s). When used in write or copy mode, pax includes a size of extended header record for each file with a size value greater than 999,999,999,999.

uid

The user ID of the user that owns the file, expressed as a decimal number using digits from ISO/IEC 646.. This record overrides the uid field in the following header block(s). When used in write or copy mode, pax includes a uid extended header record for each file whose owner ID is greater than 99,999,999.

uname

The owner of the following file(s), formatted as a user name in the user database. This record overrides the uid and uname fields in the following header block(s), and any uid extended header record. When used in read, copy, or list mode, pax translates the name from the UTF8 encoding in the header record to the character set appropriate for the user database on the receiving system. If any of the UTF8 characters cannot be translated, and if the -o invalid=UTF8 option is not specified, the results are undefined. When used in write or copy mode, pax includes a uname extended header record for each file whose user name cannot be represented entirely with the letters and digits of the portable character set.

If the value field is zero length, it deletes any header block field, previously entered extended header value, or global extended header value of the same name.

If a keyword in an extended header record (or in a -o option-argument) overrides or deletes a corresponding field in the ustar header block, pax ignores the contents of that header block field.

Extended header keyword precedence

(Applicable only to the -x pax format.)

This section describes the precedence in which the various header records and fields and command-line options are selected to apply to a file in the archive. When pax is used in read or list modes, it determines a file attribute in this sequence:

1. If -o delete=keyword-prefix is used, the affected attribute is determined from step (7) if applicable, or ignored otherwise.
2. If -o keyword:=NULL is used, the affected attribute is ignored.
3. If -o keyword:=value is used, the affected attribute is assigned the value.
4. If value exists in a file-specific extended header record, the affected attribute is assigned the value. When extended header records conflict, the last one given in the header takes precedence.
5. If -o keyword=value is used, the affected attribute is assigned the value.
6. If a value exists in a global extended header record, the affected attribute is assigned the value. When global extended header records conflict, the last one given in the global header takes precedence.
7. Otherwise, the attribute is determined from the ustar header block.

Flag 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, archive members are selected according to the user-specified pattern parameters 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, or when copying files, the files are selected according to the user-specified pathnames as modified by the -n (this option is not valid for Copy Mode) 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 the modification.
• 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.

List Mode Format Specifications

In list mode with the -o listopt=format option, the format argument is applied for each selected file. pax appends a newline character to the listopt output for each selected file. The format argument is used as the format string described in printf(), with the following exceptions:

1. The sequence keyword can occur before a format conversion specifier. The conversion argument is defined by the value of keyword. The following keywords are supported:
   • Any of the field name entries for ustar and cpio header blocks.
   • Any keyword defined for the extended header or provided as an extension within the extended header.

   For example, the sequence %(charset)s is the string value of the name of the character set in the extended header.

   The result of the keyword conversion argument is the value from the applicable header field or extended header, without any trailing NULLs.

   All keyword-values used as conversion arguments are translated from the UTF8 encoding to the character set appropriate for the local file system, user database, etc., as applicable.

2. An additional conversion character, T, specifies time formats. The T conversion character can be preceded by the sequence keyword=subformat, where subformat is a date format allowed by the date command. The default keyword is mtime and the default subformat is: %b %e %H:%M %Y.
3. An additional conversion character, M, specifies the file mode string as displayed by the ls -l command. If keyword is omitted, the mode keyword is used. For example, %.1M writes the single character corresponding to the entry type field of the ls -l command.
4. An additional conversion character, D, specifies the device for block or special files, if applicable. If not applicable and keyword is specified, then this conversion is equivalent to %keyword u. If not applicable and keyword is omitted, this conversion is equivalent to <space>.
5. An additional conversion character, F, specifies a pathname. The F conversion character can be preceded by a sequence of comma-separated keywords:

   keyword,keyword...

   The values for all the non-null keywords are concatenated together, each separated by a /. The default is path if the keyword path is defined; otherwise, the default is prefix,name.

6. An additional conversion character, L, specifies a symbolic link expansion. If the current file is a symbolic link, then %L expands to:

   "%s -> %s", value_of_keyword, contents_of_link

   Otherwise, the %L conversion character is equivalent to %F.

Exit Status

This command returns the following exit values:

Security

Attention RBAC users and Trusted AIX users: This command can perform privileged operations. Only privileged users can run privileged operations. For more information about authorizations and privileges, see Privileged Command Database in Security. For a list of privileges and the authorizations associated with this command, see the lssecattr command or the getcmdattr subcommand.

Examples

1. To copy the olddir directory hierarchy to newdir, enter:

   mkdir newdir

   pax -rw olddir newdir

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

   pax -wf /dev/rmt0

3. To archive the file xxx as XXX and display the successful substitution, enter one of the following commands:

   • pax -wvf/dev/rfd0 -s /xxx/XXX/p xxx

   • pax -wvf/dev/rfd0 -s/x/X/gp xxx

4. To read a file from a standard input and dump it to a datastream file with a specified size, enter:

   dd if=/dev/hd6 bs=36b count=480 | pax -wf /dev/rfd0 -o
   datastream=_filename_,datastr_size=_size_

5. To list the files in an archive pax.ar in a specified format, enter:

   pax -v -o listopt="start %F end" -f pax.ar

6. To create an archive pax.ar in pax format, enter :

   pax -wf pax.ar -x pax file1

7. To extract a file from an archive pax.ar in pax format with a new path, enter :

   pax -rvf pax.ar -x pax -o path=newfilename

8. To copy the contents of a symbolic link from source to destination, enter:

   pax -rwL srclink destdir

9. To extract files from the archive with group name as bin, enter:

   pax -rvf pax.ar -x pax -o gname=bin

10. To ignore the path name from the archive in pax format during extraction, enter:

    pax -rvf pax.ar -o delete=path

11. To avoid the truncation of long user and group names while creating the archive, enter:

    pax -wEf file.pax file

12. To copy the olddir directory hierarchy to newdir with ACL and EA associated with the files, enter:

    mkdir newdir
    
    pax -rUw olddir newdir

Files