Process Identity Crisis: The exec() System Call

When an established thread desires to replace its logical memory view with that of another program, “changing its stripes,” so to speak, it places a system call to exec(). The exec() call is passed the name of an executable file. The file may be either a compiled binary image or a text file to be processed as a script by an interpreter program such as the POSIX shell or PERL.

In the case of a compiled program, the file starts with a header written in a format recognizable to the operating system and containing a “magic number” indicating the hardware platform, O/S type, and version for which the code was compiled. If the magic number does not match those acceptable to the kernel, an error message ...

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