System Calls System calls provide a means for user or application programs to call upon the services of the operating system. Generally written in C or C++,although some are written in assembly for optimal performance
System Calls • System calls provide a means for user or application programs to call upon the services of the operating system. • Generally written in C or C++, although some are written in assembly for optimal performance
DEMO ·"strace”example source file destination file ·strace mkdir temp" Example System Call Sequence ·"strace cd temp" Acquire input file name Write prompt to screen 'strace date t.t" Accept input Acquire output file name 'strace cp t.tt.2" Write prompt to screen Accept input Open the input file if file doesn't exist.abort ·strace helloworld" Create output file if file exists,abort Loop Read from input file Write to output file Until read fails Close output file Write completion message to screen Terminate normally
• “strace”example • “s trace mkdir temp ” • “strace cd temp” • “strace date > t.t” • “strace cp t.t t.2” • “s trace helloworld