ar −d [−v] archive file...
ar −m [−v] archive file... ar −m −a [−v] posname archive file... ar −m −b [−v] posname archive file... ar −m −i [−v] posname archive file...
ar −p [−v] [−s] archive [file...]
ar −q [−cv] archive file...
ar −r [−cuv] archive file...
ar −r −a [−cuv] posname archive file... ar −r −b [−cuv] posname archive file... ar −r −i [−cuv] posname archive file...
ar −t [−v] [−s] archive [file...]
ar −x [−v] [−sCT] archive [file...]
- Position new files in the archive after the file named by the posname operand.
- Position new files in the archive before the file named by the posname operand.
- Suppress the diagnostic message that is written to standard error by default when the archive archive is created.
- Prevent extracted files from replacing like-named files in the file system. This option is useful when −T is also used, to prevent truncated filenames from replacing files with the same prefix.
- Delete one or more files from archive.
- Position new files in the archive before the file in the archive named by the posname operand (equivalent to −b).
- Move the named files in the archive. The −a, −b, or −i options with the posname operand indicate the position; otherwise, move the names files in the archive to the end of the archive.
- Write the contents of the files in the archive named by file operands from archive to the standard output. If no file operands are specified, the contents of all files in the archive shall be written in the order of the archive.
- Append the named files to the end of the archive. In this case ar does not check whether the added files are already in the archive. This is useful to bypass the searching otherwise done when creating a large archive piece by piece.
- Replace or add files to archive. If the archive named by archive does not exist, a new archive shall be created and a diagnostic message shall be written to standard error (unless the −c option is specified). If no files are specified and the archive exists, the results are undefined. Files that replace existing files in the archive shall not change the order of the archive. Files that do not replace existing files in the archive shall be appended to the archive unless a −a, −b, or −i option specifies another position.
- Force the regeneration of the archive symbol table even if ar is not invoked with an option that modifies the archive contents. This option is useful to restore the archive symbol table after it has been stripped; see strip.
- Write a table of contents of archive to the standard output. Only the files specified by the file operands shall be included in the written list. If no file operands are specified, all files in archive shall be included in the order of the archive.
- Allow filename truncation of extracted files whose archive names are longer than the file system can support. By default, extracting a file with a name that is too long shall be an error; a diagnostic message shall be written and the file shall not be extracted.
- Update older files in the archive. When used with the −r option, files in the archive shall be replaced only if the corresponding file has a modification time that is at least as new as the modification time of the file in the archive.
- Give verbose output. When used with the option characters −d, −r, or −x, write a detailed file-by-file description of the archive creation and maintenance activity, as described in the STDOUT section.
When used with −p, write the name of the file in the archive to the standard output before writing the file in the archive itself to the standard output, as described in the STDOUT section. When used with −t, include a long listing of information about the files in the archive, as described in the STDOUT section.
- Extract the files in the archive named by the file operands from archive. The contents of the archive shall not be changed. If no file operands are given, all files in the archive shall be extracted. The modification time of each file extracted shall be set to the time the file is extracted from the archive.
- A pathname of the archive.
- A pathname. Only the last component shall be used when comparing against the names of files in the archive. If two or more file operands have the same last pathname component (basename), the results are unspecified. The implementation's archive format shall not truncate valid filenames of files added to or replaced in the archive.
- The name of a file in the archive, used for relative positioning; see options −m and −r.
- Provide a default value for the internationalization variables that are unset or null. (See the Base Definitions volume of POSIX.1‐2008, Section 8.2, Internationalization Variables for the precedence of internationalization variables used to determine the values of locale categories.)
- If set to a non-empty string value, override the values of all the other internationalization variables.
- Determine the locale for the interpretation of sequences of bytes of text data as characters (for example, single-byte as opposed to multi-byte characters in arguments and input files).
- Determine the format and content for date and time strings written by ar −tv.
- Determine the location of message catalogs for the processing of LC_MESSAGES.
- Determine the pathname that overrides the default directory for temporary files, if any.
- Determine the timezone used to calculate date and time strings written by ar −tv. If TZ is unset or null, an unspecified default timezone shall be used.
"d − %s\n", <file>
- If file is already in the archive, the standard output format shall be:
"r − %s\n", <file>
- If file is not already in the archive, the standard output format shall be:
"a − %s\n", <file>
"%s %u/%u %u %s %d %d:%d %d %s\n", <member mode>, <user ID>, < group ID>, <number of bytes in member>, < abbreviated month>, <day-of-month>, <hour>, < minute>, <year>, <file>
- Shall be the operand specified on the command line, if file operands were specified, or the name of the file in the archive if they were not.
- <member mode>
- <abbreviated month>
- Equivalent to the format of the %H conversion specification format in date.
- Equivalent to the format of the %M conversion specification format in date.
- Equivalent to the format of the %Y conversion specification format in date.
"x − %s\n", <file>
- Successful completion.
- An error occurred.
A file created by ar begins with the ``magic'' string "!<arch>\n". The rest of the archive is made up of objects, each of which is composed of a header for a file, a possible filename, and the file contents. The header is portable between machine architectures, and, if the file contents are printable, the archive is itself printable. The header is made up of six ASCII fields, followed by a two-character trailer. The fields are the object name (16 characters), the file last modification time (12 characters), the user and group IDs (each 6 characters), the file mode (8 characters), and the file size (10 characters). All numeric fields are in decimal, except for the file mode, which is in octal. The modification time is the file st_mtime field. The user and group IDs are the file st_uid and st_gid fields. The file mode is the file st_mode field. The file size is the file st_size field. The two-byte trailer is the string "`<newline>". Only the name field has any provision for overflow. If any filename is more than 16 characters in length or contains an embedded space, the string "#1/" followed by the ASCII length of the name is written in the name field. The file size (stored in the archive header) is incremented by the length of the name. The name is then written immediately following the archive header. Any unused characters in any of these fields are written as <space> characters. If any fields are their particular maximum number of characters in length, there is no separation between the fields. Objects in the archive are always an even number of bytes long; files that are an odd number of bytes long are padded with a <newline>, although the size in the header does not reflect this.The ar utility description requires that (when all its members are valid object files) ar produce an object code library, which the linkage editor can use to extract object modules. If the linkage editor needs a symbol table to permit random access to the archive, ar must provide it; however, ar does not require a symbol table. The BSD −o option was omitted. It is a rare conforming application that uses ar to extract object code from a library with concern for its modification time, since this can only be of importance to make. Hence, since this functionality is not deemed important for applications portability, the modification time of the extracted files is set to the current time. There is at least one known implementation (for a small computer) that can accommodate only object files for that system, disallowing mixed object and other files. The ability to handle any type of file is not only historical practice for most implementations, but is also a reasonable expectation. Consideration was given to changing the output format of ar −tv to the same format as the output of ls −l. This would have made parsing the output of ar the same as that of ls. This was rejected in part because the current ar format is commonly used and changes would break historical usage. Second, ar gives the user ID and group ID in numeric format separated by a <slash>. Changing this to be the user name and group name would not be correct if the archive were moved to a machine that contained a different user database. Since ar cannot know whether the archive was generated on the same machine, it cannot tell what to report. The text on the −ur option combination is historical practice—since one filename can easily represent two different files (for example, /a/foo and /b/foo), it is reasonable to replace the file in the archive even when the modification time in the archive is identical to that in the file system.