788 Part VI . Programming in Linux If (Tomcat web server)
788 Part VI . Programming in Linux If you run the program, here s the output you get: $ ./hello Hello, Linux programming world! The command that executed the hello program specifically included the current directory, denoted with a . because having the current directory in your path is a security risk. That is, instead of a $PATH environment variable that resembles /bin:/usr/bin:/usr/local/bin:., it should be /bin:/usr/bin:/usr/ local/bin so that a cracker cannot put a dangerous command in your current directory that happens to match the name of the more benign command you really want to execute. GCC relies on file extensions to determine what kind of source code file it is, that is, in which programming language the source code is written. Table 29-1 lists the most common extensions and how GCC interprets them. Table 29-1 GCC s Filenaming Conventions Extension Type .a, .so Compiled library code .c C language source code .C, .cc C++ language source code .i Preprocessed C source code .ii Preprocessed C++ source code .m Objective-C source code .o Compiled object code .S, .s Assembly language source code Compiling Multiple Source Code Files Most non-trivial programs consist of multiple source files, and each source file must be compiled to object code before the final link step. To do so, pass gcc the name of each source code file it has to compile. GCC handles the rest. The gcc invocation might resemble: Caution
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