1.2 Controlling ar with a Script

ar -M [ <script ]

If you use the single command-line option ‘-M’ with ar, you can control its operation with a rudimentary command language. This form of ar operates interactively if standard input is coming directly from a terminal. During interactive use, ar prompts for input (the prompt is ‘AR >’), and continues executing even after errors. If you redirect standard input to a script file, no prompts are issued, and ar abandons execution (with a nonzero exit code) on any error.

The ar command language is not designed to be equivalent to the command-line options; in fact, it provides somewhat less control over archives. The only purpose of the command language is to ease the transition to GNU ar for developers who already have scripts written for the MRI “librarian” program.

The syntax for the ar command language is straightforward:

• commands are recognized in upper or lower case; for example, LIST is the same as list. In the following descriptions, commands are shown in upper case for clarity.
• a single command may appear on each line; it is the first word on the line.
• empty lines are allowed, and have no effect.
• comments are allowed; text after either of the characters ‘*’ or ‘;’ is ignored.
• Whenever you use a list of names as part of the argument to an ar command, you can separate the individual names with either commas or blanks. Commas are shown in the explanations below, for clarity.
• ‘+’ is used as a line continuation character; if ‘+’ appears at the end of a line, the text on the following line is considered part of the current command.

Here are the commands you can use in ar scripts, or when using ar interactively. Three of them have special significance:

OPEN or CREATE specify a current archive, which is a temporary file required for most of the other commands.

SAVE commits the changes so far specified by the script. Prior to SAVE, commands affect only the temporary copy of the current archive.

ADDLIB archive

ADDLIB archive (module, module, … module)

Add all the contents of archive (or, if specified, each named module from archive) to the current archive.

Requires prior use of OPEN or CREATE.

ADDMOD member, member, … member

Add each named member as a module in the current archive.

Requires prior use of OPEN or CREATE.

CLEAR

Discard the contents of the current archive, canceling the effect of any operations since the last SAVE. May be executed (with no effect) even if no current archive is specified.

CREATE archive

Creates an archive, and makes it the current archive (required for many other commands). The new archive is created with a temporary name; it is not actually saved as archive until you use SAVE. You can overwrite existing archives; similarly, the contents of any existing file named archive will not be destroyed until SAVE.

DELETE module, module, … module

Delete each listed module from the current archive; equivalent to ‘ar -d archive module … module’.

Requires prior use of OPEN or CREATE.

DIRECTORY archive (module, … module)

DIRECTORY archive (module, … module) outputfile

List each named module present in archive. The separate command VERBOSE specifies the form of the output: when verbose output is off, output is like that of ‘ar -t archive module…’. When verbose output is on, the listing is like ‘ar -tv archive module…’.

Output normally goes to the standard output stream; however, if you specify outputfile as a final argument, ar directs the output to that file.

END

Exit from ar, with a 0 exit code to indicate successful completion. This command does not save the output file; if you have changed the current archive since the last SAVE command, those changes are lost.

EXTRACT module, module, … module

Extract each named module from the current archive, writing them into the current directory as separate files. Equivalent to ‘ar -x archive module…’.

Requires prior use of OPEN or CREATE.

LIST

Display full contents of the current archive, in “verbose” style regardless of the state of VERBOSE. The effect is like ‘ar tv archive’. (This single command is a GNU ar enhancement, rather than present for MRI compatibility.)

Requires prior use of OPEN or CREATE.

OPEN archive

Opens an existing archive for use as the current archive (required for many other commands). Any changes as the result of subsequent commands will not actually affect archive until you next use SAVE.

REPLACE module, module, … module

In the current archive, replace each existing module (named in the REPLACE arguments) from files in the current working directory. To execute this command without errors, both the file, and the module in the current archive, must exist.

Requires prior use of OPEN or CREATE.

VERBOSE

Toggle an internal flag governing the output from DIRECTORY. When the flag is on, DIRECTORY output matches output from ‘ar -tv ’….

SAVE

Commit your changes to the current archive, and actually save it as a file with the name specified in the last CREATE or OPEN command.

Requires prior use of OPEN or CREATE.