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Time Dimension, Processes, Data Flow

Action: Create data, Destroy Data, Modify data ---> Processes

Process Data Representation

Executables: run as: /PATH/filename

• scripts (interpreted executables)
  
  • magic number/shebang:  #! interpreter
  • permissions: executable
  • interpreter: /bin/bash, /usr/bin/perl
  • file name extension: .pl .sh
• binaries (compiled executables)
  
  • binary formats: a.out, elf
  • fed to the processor by the kernel
    

Application files (text or binary):

• run as:  /PATH/interpreter filename
• magic number: Postscript: %!, Image formats: specific binary sequence,
                                file name extension: .ps .doc .gif  .xls
• interpreters: gv(Postscript), xv(pictures), emacs(text), pico(text),
                               soffice(MSOffice files)

• languages: Fortran, C
• compile: cc -o name name.c -lm ---> objects (*.o) ---> binaries 
• libraries (static: .a, dynamic: .so), includes
• debuggers, tools (macroprocessor, make, configure)

Process Communication

Process Management

• Executable: binary, script
• Libraries: dynamic, static(?)
• Configuration: files(system-wide, user level), environment variables
  
• Command line option: see the man page
• Documentation:
• man page
• info
• graphical interface based help
• package info, listing: rpm -q(ifl), dpkg-query -(lLSp)
  
• extensive documentation: /usr/share/doc, /usr/doc, /usr/local/doc

• The kernel
• Administrative
  
  • resource management
  • logging
• Server Daemons
• User processes
  
  • root/administrative accounts
  • real user accounts
    

• Multiuser
• Multiprocessor
• Multitasking
• Multithreads

• no file locks or signals inherited
• if children perform part of the same task using shared memory: threads

• kernel: uname -a
  
• run details: ps aux, top
• run list: jobs
• version: the version flag
  

• run mode: fg, bg
• priority: nice, renice
• send signals: kill
  
  • signals: 9, HUP