Unix Systems Administration 1Y. K. Chang Reasons for UNIX’s success 4 Written in high level language –easy to read, understand, change, and move to other machine –drawback: slower than written in assembly 4 simple user interface: shell 4 primitives that permit complex programs to be built from simpler programs elm guest < homework1 –redirect I/O: standard input, output, error files (stdio, stdout, stderr), elm guest < homework1

Unix Systems Administration 2Y. K. Chang Reasons for UNIX’s success –pipe: allows stream of data to be passed between reader and writer processes. –man man |col -b |enscript -2rG -h -Php 4 UNIX file system –hierarchical file system –consistent file format, the byte stream –dynamic growth of files –file protection –treatment of peripheral devices as files last |grep |grep sept|elm ykchang

Unix Systems Administration 3Y. K. Chang Reasons for UNIX’s success 4 Multi-user and multi-process environment –A program is an executable file, and a process is an instance of the program in execution –Processes can create, terminate, synchronize, and control reaction of various events –preemptive, time-sharing, time quantum –signal, shared memory –fork(), &,...

Unix Systems Administration 4Y. K. Chang Reasons for UNIX’s success 4 hide the machine hardware from users Hardware Kernel cc Other app shell grep