pax(1)

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 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.)

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 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.

If a symbolic link referencing a file of type directory is specified on the command line, pax shall archive the file hierarchy rooted in the file referenced by the link, using the name of the link as the root of the file hierarchy. Otherwise, if a symbolic link referencing a file of any other file type which pax can normally archive is specified on the command line, then pax shall archive the file referenced by the link, using the name of the link. The default behavior shall be to archive the symbolic link itself.

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.

If a symbolic link referencing a file of type directory is specified on the command line or encountered during the traversal of a file hierarchy, pax shall archive the file hierarchy rooted in the file referenced by the link, using the name of the link as the root of the file hierarchy. Otherwise, if a symbolic link referencing a file of any other file type which pax can normally archive is specified on the command line or encountered during the traversal of a file hierarchy, pax shall archive the file referenced by the link, using the name of the link. The default behavior shall be to archive the symbolic link itself.

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).

Provides information to the implementation to modify the algorithm for extracting or writing files. The value of options shall consist of one or more comma-separated keywords of the form:

keyword[[:]=value][,keyword[[:]=value, ]...]

Some keywords apply only to certain file formats, as indicated with each description. Use of keywords that are inapplicable to the file format being processed causes pax to print an error message and ignore the keyword. However pax will continue processing the archive. Keywords in the options argument shall be a string that would be a valid portable filename as described in the Base Definitions volume of IEEE Std 1003.1-2001, Section 3.276, Portable Filename Character Set.

Note: Keywords are not expected to be filenames, merely to follow the same character composition rules as portable filenames.

The value field shall consist of zero or more characters; within value, the application shall precede any literal comma with a backslash, which shall be ignored, but preserves the comma as part of value. A comma as the final character, or a comma followed solely by white space as the final characters, in options shall be ignored. Multiple -o options can be specified; if keywords given to these multiple -o options conflict, the keywords and values appearing later in command line sequence shall take precedence and the earlier shall be silently ignored. Also, if the value specified for a keyword is invalid, pax shall print a suitable error message and behave as if the keyword were not specified in the command line. The following keyword values of options shall be supported for the file formats as indicated:

In addition to these keywords, if the -x pax format is specified, any of the keywords and values defined in pax Extended Header can be used in -o option-arguments, in either of two modes:

When used in write or copy mode, these keyword/value pairs shall be included at the beginning of the archive as typeflag g global extended header records. When used in read or list mode, these keyword/value pairs shall act as if they had been at the beginning of the archive as typeflag g global extended header records.

When used in write or copy mode, these keyword/value pairs shall be included as records at the beginning of a typeflag x extended header for each file. (This shall be equivalent to the equal-sign form except that it creates no typeflag g global extended header records.) When used in read or list mode, these keyword/value pairs shall act as if they were included as records at the end of each extended header; thus, they shall override any global or file-specific extended header record keywords of the same names. For example, in the command below, the group name will be forced to a new value for all files read from the archive:

The precedence of -o keywords over various fields in the archive is described in pax Extended Header Keyword Precedence.

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:

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 shall take precedence. For example, if -p eme is specified, file-modification times are retained.

Reads an archive file from the standard input.

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:

whereas 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 non-null 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.

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 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.

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.

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

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

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.

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.

Defined in the EXTENDED DESCRIPTION section of printf.

The sequence (keyword) can occur before a format conversion specifier. The conversion argument is defined by the value of keyword. The implementation shall support the following keywords:

An additional conversion specifier character, T, shall be used to specify time formats. The T conversion specifier character can be preceded by the (keyword=subformat) sequence where subformat is a date format as defined by date operands. The default keyword shall be mtime and the default subformat shall be:

%b %e %H:%M %Y

An additional conversion specifier character, M, shall be used to specify the file mode string as defined in ls Standard Output. If (keyword) is omitted, the mode keyword shall be used. For example, %.1M writes the single character corresponding to the entry_type field of the ls -l command

An additional conversion specifier character, D, shall be used to specify the device for block or special files, if applicable. If not applicable, and (keyword) is specified, then this conversion shall be equivalent to %(keyword)u. If not applicable, and (keyword) is omitted, then this conversion shall be equivalent to space.

An additional conversion specifier character, F, shall be used to specify a pathname. The F conversion character can be preceded by a sequence of comma-separated keywords:

(keyword[,keyword] ...)

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

An additional conversion specifier character, L, shall be used to specify a symbolic line expansion. If the current file is a symbolic link, then %L shall expand to:

%s -> %s, value_of_keyword, contents_of_link

Otherwise, the %L conversion specification shall be the equivalent of %F.

Identify the archive as being a transportable archive by containing the identifying value "070707".

Contains values that uniquely identify the file within the archive. No files contain the same pair of c_dev and c_ino values unless they are links to the same file.

Contains the file type and access permissions.

Contains the user ID of the owner of the file.

Contains the group ID of the group owner of the file.

Contains the number links of the file.

Contains information for character or block special files.

Contains the latest time of modification of the file at the time the archive was created.

Contains the length of the pathname, including the terminating NUL character.

Contains the length of the file in bytes. This shall be the length of the data section following the header structure.

The name and the prefix fields shall produce the pathname of the file. A new pathname shall be formed, if prefix is not an empty string (its first character is not NUL), by concatenating prefix (up to the first NUL character), a slash character, and name; otherwise, name is used alone. In this manner, pathnames up to 256 characters can be supported. If a pathname does not fit in the space provided, pax shall notify the user of the error, and shall not store any part of the file-header or data on the medium.

The mode field provides 12 bits encoded in the ISO/IEC 646:1991 standard octal digit representation to encode the permissions.

The user and group ID of the owner and group of the file, respectively. If uid or gid is greater than 2097151, a value of -1 will be stored in the respective field of the ustar header. If the corresponding name (user name for uid and group name for gid) also could not be stored in the archive, pax shall notify the user of the error but shall include the other attributes of the file and its data on the medium.

The names of the owner and group of the file, respectively. If the user or group name is longer than 31 characters, it will not be stored in the respective field of the ustar header. pax shall notify the user of the error but shall include the other attributes of the file and its data on the medium.

The size of the file in bytes. If the size of the files is greater than or equal to 8GB, pax shall notify the user of the error, and shall not store any part of the file-header or data on the medium.

The modification time of the file at the time it was archived.

Specifies the type of file archived. All of the typeflag fields shall be coded in the ISO/IEC 646:1991 standard IRV

The linkname is the pathname of the target of a symbolic or hard link. It is limited to 100 characters. If the name does not fit in the space provided, pax shall notify the user of the error, and shall not attempt to store the link on the medium.

When the typeflag field contains '3' or '4' the devmajor and devminor fields shall contain the major and minor numbers of the device respectively.

The octal value of the simple sum of all bytes in the header logical record. Each bytes in the header shall be treated as an unsigned value. When calculating the checksum, the chksum field is treated as if it were all spaces.

The magic field is the specification that this archive was output in this archive format. If this field contains ustar (the five characters from the ISO/IEC 646:1991 standard IRV shown followed by NUL), the uname and gname fields shall contain the ISO/IEC 646:1991 standard IRV representation of the owner and group of the file, respectively. When the file is restored by a privileged, protection-preserving version of the utility, the user and group databases shall be scanned for these names. If found, the user and group IDs contained within these files shall be used rather than the values contained within the uid and gid fields.

The version field is two bytes containing the characters "00" (zero-zero).

An optional header block with extended header records. This header is of the form described in pax Header Block with a typeflag value of x or g. The extended header records, described in pax Extended Header shall be included as the data for this header block.

A header block that describes the file. Any fields in the preceding optional extended header shall override the associated fields in this header block for this file.

Zero or more blocks that contain the contents of the file.

Represents extended header records for the following file in the archive (which shall have its own ustar header block). The format of these extended header records shall be as described in the pax Extended Header section of this manpage.

Represents global extended header records for the following files in the archive. The format of these extended header records shall be as described in pax Extended Header. Each value shall affect all subsequent files that do not override that value in their own extended header record and until another global extended header record is reached that provides another value for the same field. The typeflag g global headers should not be used with interchange media that could suffer partial data loss in transporting the archive.

The file access time for the following file(s), equivalent to the value of the st_atime member of the stat structure for a file, as described by the stat() function. The format of the value shall be as described in pax Extended Header File Times.

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

The group ID of the group that owns the file, expressed as a decimal number using digits from the ISO/IEC 646:1991 standard. This record shall override the gid field in the following header block(s). When used in write or copy mode, pax shall include a gid extended header record for each file whose group ID is greater than 2097151 (octal 7777777).

The group of the file(s), formatted as a group name in the group database. This record shall override the gid and gname fields in the following header block(s), and any gid extended header record. When used in write or copy mode, pax shall include a gname extended header record for each file whose group name cannot be represented in the ustar header.

The pathname of a link being created to another file, of any type, previously archived. This record shall override the linkname field in the following ustar header block(s). The following ustar header block shall determine the type of link created. If typeflag of the following header block is 1, it shall be a hard link. If typeflag is 2, it shall be a symbolic link and the linkpath value shall be the contents of the symbolic link. When used in write or copy mode, pax shall include a linkpath extended header record for each link whose pathname cannot be represented in the ustar header.

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, as described in the stat() function. This record shall override the mtime field in the following header block(s). The modification time shall be restored if the process has the appropriate privilege required to do so. The format of the value is described in pax Extended Header File Times.

The pathname of the following file(s). This record shall override the name and prefix fields in the following header block(s). When used in write or copy mode, pax shall include a path extended header record for each file whose pathname cannot be represented entirely in the ustar header.

The size of the file in bytes, expressed as a decimal number using digits from the ISO/IEC 646:1991 standard. This record shall override the size field in the following header block(s). When used in write or copy mode, pax shall include a size extended header record for each file with a size value greater than 8589934591 (octal 77777777777).

The user ID of the file owner, expressed as a decimal number using digits from the ISO/IEC 646:1991 standard. This record shall override the uid field in the following header block(s). When used in write or copy mode, pax shall include a uid extended header record for each file whose owner ID is greater than 2097151 (octal 7777777).

The owner of the following file(s), formatted as a user name in the user database. This record shall override the uid and uname fields in the following header block(s), and any uid extended header record. When used in write or copy mode, pax shall include a uname extended header record for each file whose user name cannot be represented entirely in the ustar header.

If -o delete= keyword-prefix is used, the affected attributes shall be determined from Step 7., if applicable, or ignored otherwise.

If -o keyword:= is used, the affected attributes shall be ignored.

If -o keyword:=value is used, the affected attribute shall be assigned the value.

If there is a typeflag x extended header record, the affected attribute shall be assigned the value. When extended header records conflict, the last one given in the header shall take precedence.

If -o keyword=value is used, the affected attribute shall be assigned the value.

If there is a typeflag g global extended header record, the affected attribute shall be assigned the value. When global extended header records conflict, the last one given in the global header shall take precedence.

Otherwise, the attribute shall be determined from the ustar header block.