Program: TarList (File Converter)
This program provides easy access to tar -format
files using an interface similar to that used for zip archives in
Section 9.19. Unix users will be familiar with the
tar program, an archiver first written back in
the mid-1970s. And JDK users might find the tar
program syntax somewhat familiar, as it was the basis for the
command-line Java Archiver (jar)
program in the JDK, written 20 years later. If you’re not a
Unix user, don’t dismay: just think of this as an example of a
whole category of programs, those that need to repetitively read and
write files in a special-purpose, predefined format. MS-Windows is
full of special-purpose file formats, as are many other operating
systems. Unlike jar, tar is
just an archiver, not a combined archiver and compressor, so its
format is somewhat simpler. In this section we’ll develop a
program that reads a tar
archive
and lists the contents. The TarList
program
combines several reading methods with several formatting methods. So
the commands:
tar -xvf demo.tar java TarList demo.tar
should produce the same output. And indeed they do, at least for some files and some versions of tar, when run on a small tar archive:
$ java TarList demo.tar -rwxr-xr-x ian/wheel 734 1999-10-05 19:10 TarDemo.class -rwxr-xr-x ian/wheel 431 1999-10-05 19:10 TarList.java -rw-r--r-- ian/wheel 0 1999-10-05 19:10 a -rw-r--r-- ian/wheel 0 1999-10-05 19:10 b link to a lrwxr-xr-x ian/wheel 0 1999-10-05 19:10 c -> a $ tar -tvf demo.tar -rwxr-xr-x ...
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