pax (讀取和寫入歸檔文件的內容，而與歸檔文件格式無關)

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命令行 Unix&Linux命令 pax

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在類似Unix的操作系統上，pax命令讀取和寫入歸檔文件的內容，而與歸檔文件格式無關。

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1 pax 運行系統環境

2 pax 描述

3 pax 語法

4 pax 例子

pax 運行系統環境

Linux

pax 描述

本文檔介紹了pax的Linux版本。

“ Pax”是“便攜式歸檔交換”的縮寫。該軟件支持許多主要的存檔格式。它可以讀取每個文件的內容，并將它們寫入新的單個存檔中。

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pax 語法

pax [-c] [-d] [-n] [-v] [-f archive] [-s replstr] [pattern]

pax -r [-c] [-d] [-i] [-k] [-n] [-u] [-v] [-f archive] [ -o options] 
    [-p string] [-s replstr] [pattern]

pax -w [-d] [-i] [-t] [-u] [-v] [-X] [-b blocksize] [-a] i [-f archive] 
    [-o options] [-s replstr] [-x format] [file]

pax -r -w [-d] [-i] [-k] [-l] [-n] [-t] [-u] [-v] [-X] [-p string] 
    [-s replstr] [file] directory

-C

匹配所有文件或歸檔成員，但模式或文件操作數指定的成員除外。

-d

導致目錄類型的文件被復制或歸檔，或者目錄類型的歸檔成員被提取為僅匹配文件或歸檔成員本身，而不匹配根于該文件的文件層次結構。

-n

選擇與每個模式操作數匹配的第一個存檔成員。每種模式最多只能匹配一個存檔成員（盡管類型為directory的成員仍將匹配以該文件為根的文件層次結構）。

-v

在列表模式下，生成詳細的目錄（請參見標準輸出）。否則，將存檔成員路徑名寫入標準錯誤（請參見標準錯誤）。

-r

從標準輸入中讀取存檔文件。

-i

交互式重命名文件或存檔成員。對于每個與模式操作數匹配的存檔成員或與文件操作數匹配的文件，將在文件/ dev / tty中寫入提示。該提示將包含文件或存檔成員的名稱。然后從/ dev / tty中讀取一行。如果此行為空，則將跳過文件或存檔成員。如果此行包含單個句點，則將在不修改文件名或文件名的情況下對其進行處理。否則，其名稱將替換為該行的內容。在PAX命令將立即以非零退出狀態退出，如果-的文件末尾讀取響應時遇到或者的/ dev / tty的不能打開閱讀和寫作。

-k

防止覆蓋現有文件。

-l

鏈接文件。在復制模式下，將盡可能在源文件層次結構和目標文件層次結構之間建立硬鏈接。

-u

忽略比相同名稱的現有文件或歸檔成員更舊的文件（文件修改時間更短）。

閱讀模式	如果存檔成員比文件新，則將提取與文件系統中文件名稱相同的存檔成員。
寫模式	如果文件比存檔成員新，則與文件系統中文件名稱相同的存檔文件成員將被取代。
復制模式	如果源層次結構中的文件較新，則目標層次結構中的文件將被源層次結構中的文件或源層次結構中文件的鏈接替換。

-t

使歸檔文件的訪問時間與pax讀取之前的訪問時間相同。

-X

遍歷路徑名指定的文件層次結構時，pax不會下降到具有不同設備ID（st_dev）的目錄中。

-w

將文件以指定的存檔格式寫入標準輸出。

-a

將文件追加到歸檔文件的末尾。該選項不適用于某些存檔設備，例如1/4英寸流磁帶和8mm磁帶。

-f archive

指定輸入或輸出歸檔文件的路徑名，以覆蓋默認的標準輸入（在列表或讀取模式下）或標準輸出（在寫模式下）。

-s replstr

使用替換表達式replstr修改基于模式或文件操作數命名的文件或歸檔成員名稱，該替換表達式基于ed s（替代）命令，使用正則表達式手冊頁上的正則表達式語法。在pax命令的上下文中，“地址”和“行”的概念無意義，因此不能提供。格式為：

-s /old/new/ [gp]

其中，如在ed，old是一個基本的正則表達式和新可以包含符號（“ ＆ ‘）或’ \ n ”反向引用，其中?是一個數字。還允許舊字符串包含換行符。

任何非空字符都可以用作分隔符（此處顯示“ / ”）。可以指定多個-s表達式；表達式將以指定的順序應用，并以第一個成功替換結束。可選的尾隨g如ed命令中所定義。可選的尾隨p會導致成功替換寫入標準錯誤。讀寫檔案時，將替換為空字符串的文件或檔案成員名稱。

-b blocksize

每次寫入存檔文件時，以正十進制整數字節形式阻止輸出。設備和存檔格式可能會對阻止施加限制。根據輸入自動確定阻塞。可移植應用程序不得指定大于32256的塊大小值。創建檔案時的默認阻止取決于檔案格式。（請參閱下面的-x選項。）

-o options

保留用于特定于格式的特殊選項。

-p string

指定一個或多個文件特征選項（特權）。字符串選項參數必須是一個字符串，該字符串指定要在提取時保留或丟棄的文件特征。該字符串由規范字符a，e，m，o和p組成。可以在同一字符串中串聯多個特征，并且可以指定多個-p選項。規范字符的含義如下：

a	不保留文件訪問時間。
e	保留用戶ID，組ID，文件模式位，訪問時間和修改時間。
m	不要保留文件修改時間。
o	保留用戶ID和組ID。
p	保留文件模式位。可以保留其他與實現相關的文件模式屬性。

在前面的列表中，“保留”表示將根據調用過程的權限將檔案中存儲的屬性賦予提取的文件；否則，該屬性將被確定為正常文件創建操作的一部分。

如果未指定e或o規范字符，或者由于任何原因未保留用戶ID和組ID，則pax將不會設置文件模式的setuid和setgid位。

如果任何這些項目的保存由于任何原因而失敗，pax都會將診斷消息寫入標準錯誤。無法保留這些項目將影響最終退出狀態，但不會導致提取的文件被刪除。

如果任何字符串選項參數中的文件特性字母重復或彼此沖突，則最后給出的字母優先。例如，如果指定-p eme，則將保留文件修改時間。

-x format

指定輸出存檔格式。在PAX命令識別以下格式：

cpio

擴展的cpio交換格式；請參閱IEEE 1003.1（1990）規范。字符特殊存檔文件的此格式的默認塊大小為5120。實現支持所有小于或等于32256的值（均為512的倍數）的塊大小。

此存檔格式允許將UID和GID最多為262143的文件存儲在存檔中。UID和GID大于此值的文件將以UID和GID為60001存檔。

Ustar

擴展的tar交換格式；請參閱IEEE 1003.1（1990）規范。對于字符特殊存檔文件，此格式的默認塊大小為10240。實現支持所有小于或等于32256的塊大小值，該值是512的倍數。

任何以不同于現有存檔格式的格式追加到存檔文件的嘗試都會導致pax立即以非零退出狀態退出。

這種存檔格式允許UID和GID最高為2097151的文件存儲在存檔中。UID和GID大于此值的文件將以UID和GID為60001存檔。

pattern

一種與歸檔成員的一個或多個路徑名匹配的模式。模式必須符合在fnmatch手冊頁上找到的模式匹配符號。如果未指定模式，則默認值為選擇存檔中的所有成員。

file

要復制或歸檔的文件的路徑名。

directory

復制模式的目標目錄路徑名。

pax [-c] [-d] [-n] [-v] [-f archive] [-s replstr] [pattern]

pax -r [-c] [-d] [-i] [-k] [-n] [-u] [-v] [-f archive] [ -o options] 
    [-p string] [-s replstr] [pattern]

pax -w [-d] [-i] [-t] [-u] [-v] [-X] [-b blocksize] [-a] i [-f archive] 
    [-o options] [-s replstr] [-x format] [file]

pax -r -w [-d] [-i] [-k] [-l] [-n] [-t] [-u] [-v] [-X] [-p string] 
    [-s replstr] [file] directory

-c

Match all file or archive members except those specified by the pattern or file operands.

-d

Cause files of type directory being copied or archived or archive members of type directory being extracted to match only the file or archive member itself and not the file hierarchy rooted at the file.

-n

Select the first archive member that matches each pattern operand. No more than one archive member will be matched for each pattern (although members of type directory will still match the file hierarchy rooted at that file).

-v

In list mode, produce a verbose table of contents (see Standard Output). Otherwise, write archive member path names to standard error (see Standard Error).

-r

Read an archive file from standard input.

-i

Interactively rename files or archive members. For each archive member matching a pattern operand or file matching a file operand, a prompt will be written to the file /dev/tty. The prompt will contain the name of the file or archive member. A line will then be read from /dev/tty. If this line is blank, the file or archive member will be skipped. If this line consists of a single period, the file or archive member will be processed with no modification to its name. Otherwise, its name will be replaced with the contents of the line. The pax command will immediately exit with a non-zero exit status if end-of-file is encountered when reading a response or if /dev/tty cannot be opened for reading and writing.

-k

Prevent the overwriting of existing files.

-l

Link files. In copy mode, hard links will be made between the source and destination file hierarchies whenever possible.

-u

Ignore files that are older (having a less recent file modification time) than a pre-existing file or archive member with the same name.

read mode	an archive member with the same name as a file in the file system will be extracted if the archive member is newer than the file.
write mode	an archive file member with the same name as a file in the file system will be superseded if the file is newer than the archive member.
copy mode	the file in the destination hierarchy will be 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.

-t

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

-X

When traversing the file hierarchy specified by a path name, pax will not descend into directories that have a different device ID (st_dev).

-w

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

-a

Append files to the end of the archive. This option will not work for some archive devices, such as 1/4-inch streaming tapes and 8mm tapes.

-f archive

Specify the path name of the input or output archive, overriding the default standard input (in list or read modes) or standard output (write mode).

-s replstr

Modify file or archive member names named by pattern or file operands according to the substitution expression replstr, which is based on the ed s (substitution) command, using the regular expression syntax on the regex manual page. The concepts of "address" and "line" are meaningless in the context of the pax command, and must not be supplied. The format is:

-s/old/new/[gp]

where, as in ed, old is a basic regular expression and new can contain an ampersand ("&") or a "\n" backreference, where n is a digit. The old string also is permitted to contain newline characters.

Any non-null character can be used as a delimiter ( "/" is shown here). Multiple -s expressions can be specified; the expressions will be applied in the order specified, terminating with the first successful substitution. The optional trailing g is as defined in the ed command. The optional trailing p causes successful substitutions to be written to standard error. File or archive member names that substitute to the empty string are ignored when reading and writing archives.

-b blocksize

Block the output at a positive decimal integer number of bytes per write to the archive file. Devices and archive formats may impose restrictions on blocking. Blocking is automatically determined on input. Portable applications must not specify a blocksize value larger than 32256. Default blocking when creating archives depends on the archive format. (See the -x option below.)

-o options

Reserved for special format-specific options.

-p string

Specify one or more file characteristic options (privileges). The string option-argument must be a string specifying file characteristics to be retained or discarded on extraction. The string consists of the specification characters a, e, m, o, and p. Multiple characteristics can be concatenated within the same string and multiple -p options can be specified. The meaning of the specification characters are as follows:

a	Do not preserve file access times.
e	Preserve the user ID, group ID, file mode bits, access time, and modification time.
m	Do not preserve file modification times.
o	Preserve the user ID and group ID.
p	Preserve the file mode bits. Other, implementation-dependent file-mode attributes may be preserved.

In the preceding list, "preserve" indicates that an attribute stored in the archive will be given to the extracted file, subject to the permissions of the invoking process; otherwise, the attribute will be determined as part of the normal file creation action.

If neither the e nor the o specification character is specified, or the user ID and group ID are not preserved for any reason, pax will not set the setuid and setgid bits of the file mode.

If the preservation of any of these items fails for any reason, pax will write a diagnostic message to standard error. Failure to preserve these items will affect the final exit status, but will not cause the extracted file to be deleted.

If file-characteristic letters in any of the string option-arguments are duplicated or conflict with each other, the ones given last will take precedence. For example, if -p eme is specified, file modification times will be preserved.

-x format

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

cpio

The extended cpio interchange format; see the IEEE 1003.1(1990) specifications. The default blocksize for this format for character special archive files is 5120. Implementations support all blocksize values less than or equal to 32256 that are multiples of 512.

This archive format allows files with UIDs and GIDs up to 262143 to be stored in the archive. Files with UIDs and GIDs greater than this value will be archived with the UID and GID of 60001.

ustar

The extended tar interchange format; see the IEEE 1003.1(1990) specifications. The default blocksize for this format for character special archive files is 10240. Implementations support all blocksize values less than or equal to 32256 that are multiples of 512.

Any attempt to append to an archive file in a format different from the existing archive format will cause pax to exit immediately with a non-zero exit status.

This archive format allows files with UIDs and GIDs up to 2097151 to be stored in the archive. Files with UIDs and GIDs greater than this value will be archived with the UID and GID of 60001.

pattern

A pattern matching one or more path names of archive members. A pattern must conform to the pattern matching notation found on the fnmatch manual page. The default, if no pattern is specified, is to select all members in the archive.

file

A path name of a file to be copied or archived.

directory

The destination directory path name for copy mode.

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pax 例子

pax -w -f /dev/rmt/1m

將當前目錄的內容復制到中等密度的磁帶機1。

pax -w -f /dev/rmt/1m

Copies the contents of the current directory to tape drive 1, medium density.

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