Java™ Application Development on Linux - Dator

1.3 Basic Linux Concepts and Commands29TIPHere’s one more handy example we know you’ll use:find . -name '*.java' -print | zip allmysource -@This command starts in the current directory (“.”) finding every file that ends in.java and gives their names to zip which will read them from standard in insteadof its argument list (told to do so with the -@ argument) and zip them allinto an archive named allmysource.zip. To put it simply, it will zip up allyour Java source files from the current directory on down.1.3.12 The man CommandPrimitive but handy, the man command (short for manual ) was the earlyUNIX online manual. While we’ve come to expect (and ignore) online help,the idea of online manuals was rather revolutionary in the early days of UNIX.In contrast to walls of printed documentation, UNIX provided terse butdefinitive descriptions of its various commands. When they are done well, thesedescriptions are an invaluable handy reference. They are not the best way tolearn about a command, but they can be a great guide to using the command’soptions correctly.The format is simply man followed by the name of the command aboutwhich you want information. So man man will tell you about the mancommand itself.The most useful option to man is the -k option. It will do a keywordsearch in the titles of all the manpages looking for the keyword that you give.Try typing man -k java to see what commands are available. The (1) meansthat it’s a user command—something that you can type from the shell prompt,as opposed to (2) which is a system call or (3) which is a C library call. Thesenumbers refer to the original UNIX documentation volumes (volume one wasshell commands and so on), and it all fit into a single three ring binder.TIPOne other way to find out something about a command, if you know the commandname already, is to ask the command itself for help. Most commandshave either a -? or --help option. Try --help first. If you need to type -?either put it in single quotes or type it with a backslash before the question mark,as in -\?, since the ? is a pattern-matching character to the shell.