Java™ Application Development on Linux - Dator

16Chapter 1An Embarrassment of Riches: The Linux Environmentis a compiled class file). The long listing ls -l will tell us more: permissions,links, owner, group, size (in bytes), and the date of last modification.$ ls -ltotal 2414-rw-r--r-- 1 albing users 132 Jan 22 07:53 ReadMe.txt-rw-r--r-- 1 albing users 637 Jan 22 07:52 Shift.class-rw-r--r-- 1 albing users 336 Jan 22 07:55 Shift.java-rw-r--r-- 1 albing users 1374 Jan 22 07:58 anIcon.gif-rw-r--r-- 1 albing users 8564 Jan 22 07:59 dispColrs-rw-r--r-- 1 albing users 1943 Jan 22 08:02 jam.jardrwxr-xr-x 2 albing users 48 Jan 22 07:52 moresrc-rw-r--r-- 1 albing users 2435522 Jan 22 07:56 moresrc.zip$While ls is only looking at the “outside” of files, 5 there is a command thatlooks at the “inside,” the data itself, and based on that, tries to tell you whatkind of file it found. The command is called file, and it takes as arguments alist of files, so you can give it the name of a single file or you can give it a wholelong list of files.NOTERemember what was said about pattern matching in the shell: we can let theshell construct that list of files for us. We can give file the list of all the filesin our current directory by using the “*” on the command line so that the shelldoes the work of expanding it to the names of all the files in our directory (sinceany filename will match the star pattern).$ file *ReadMe.txt: ASCII textShift.class: compiled Java class data, version 45.3Shift.java: ASCII Java program textanIcon.gif: GIF image data, version 89a, 26 x 26,dispColrs: PNG image data, 565 x 465, 8-bit/color RGB, non-interlacedjam.jar: Zip archive data, at least v2.0 to extractmoresrc: directorymoresrc.zip: Zip archive data, at least v1.0 to extract$5. Technically, ls (without arguments) need only read the directory, whereas ls -l looks atthe contents of the inode in order to get all the other information (permissions, size, and soon), but it doesn’t look at the data blocks of the file.