2019.09.19.pdf - Announcements ‣ out-of-class midterm exam •17:30(5:30 p.m – 19:00(7:00 p.m on Monday •HLTH E1150 1 Announcements ‣ Student

2019.09.19.pdf - Announcements ‣ out-of-class midterm...

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Announcements out-of-class midterm exam •17:30 (5:30 p.m.) – 19:00 (7:00 p.m.) on Monday, October 28, 2019 •HLTH E1150 1
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Announcements Student Learning Services •example course: "Managing Your Time and Tasks" •12:30 – 13:20, Friday, Sept 20 •Murray Library 102 •see listEvents?currentSystemId=1 for list of events 2
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see Cartoon of the Day 3
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Review 4
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Basic Process Abstraction in UNIX processes exist in a hierarchy parent/child/sibling model •each process has a unique parent •processes can have multiple children - each child will be a sibling of the other children each process identified by a unique identifier, its PID in UNIX creation of a child is similar to a clone operation •child begins execution with a copy of the parent's address space 5
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Basic Process Abstraction in UNIX 6 process abstraction involved in executing a command from the shell •for simplicity many stages not shown lexical analysis and parsing tilde expansion variable and parameter expansion file name generation command execution input I/O redirection expand on these
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Basic Process Abstraction in UNIX 7 process abstraction involved in executing a command from the shell input lexical analysis and parsing various expansions; filename patterns create child process tell O/S to load and start executable program control child process program executes I/O redirection child process
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Basic Process Abstraction in UNIX 8 process abstraction involved in executing a command from the shell create child process tell O/S to load executable program into process's memory and start it control child process I/O redirection child process target program executes shell program N.B. target program not involved in setting up redirection
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Commands Related to UNIX Processes list processes •ps pstree -h on tuxworld •top uptime w and who exit (built-in) and ^D (end-of-file) 9
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On to today's material … 10
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Processes and Jobs process state: output by ps -l (LINUX) or ps -v (BSD) •typical process states: - R : "running or runnable" - S : "sleep" (waiting for an event to complete) - T : "stopped" (stopped by job control signal) •other states 11
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Commands Related to UNIX Processes eliminate processes kill •man 7 signal signals generated by keyboard action: SIGINT , SIGQUIT useful signals for users: SIGKILL , SIGTERM /usr/bin/kill or /bin/kill for bash kill built-in for csh man 1 kill or info kill 12
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Processes and Jobs warning: UNIX shell specific definitions foreground process: •a process that is associated with user input •usually means “has control of the keyboard” •shell waits for its completion background process: •a process that executes whenever permitted by the OS •usually means “does not require user interaction” •shell does not wait for its completion 13
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Processes and Jobs job : •a suspended or background running process •jobs suspended process:
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