Week Fourteen Agenda

Week Fourteen AgendaAnnouncements

Final Exam True/False -100 questions (1 point per question)Multiple Choice - 40 questions (2 points per

question)Essay -10 questions (2 point per question)Final Exam Total Points 200Review questions on the final examIf there are problems associated with taking the exam, call me at 614.519.5853 and be persistent.

Week Fourteen AgendaAgendaWeek Fourteen December 9, 2013 Open Source presenter(s) are:Student name: Stacy ZimmermanOpen source topic: Brain Workshop (14)Student name: Paul BurkholderOpen source topic: Asterisk (14)Student name: Paula Godley-CooperOpen source topic: Funambol (14)Student name: Anne SalmonOpen source topic: CamStudio (14)Student name: Clarence IrbyOpen source topic:Ganglia Monitoring System (14)

Week Fourteen AgendaAgenda Week Fourteen December 9, 2013 Open Source presenter(s) are:Student name: Nathan StockwellOpen source topic: DD-WRT (14)

Week Fourteen AgendaFinal Exam QuestionsWhen a child process ends, a SIGCHLD signal is sent to the parent process from the kernel indicating their child exited (True).When a child process ends, the kernel sends a SIGCHLD signal to the parent. If the parent responses immediately with a wait () system call, all memory and resources allocated to the process are de-allocated (True).To remove a zombie process from a system, the kernel sends a SIGHUB signal to the parent process (False).The /etc/inittab file for RHEL 6.0 does not contains a list of run levels that can be used during the boot process. (True)Would the initdefault run level variable be found in the /etc/inittab file for RHEL 6.0? (True)

Week Fourteen AgendaFinal Exam Questions

The wait action keyword is used when a specific run level is entered for action. (True)

The respawn action keyword is used to re-start a process whenever it has terminated. (True)

When the system run level is changed, any running processes that are not specified for the new run level are killed. The unwanted processes are first sent a SIGTERM signal, then a SIGKILL signal. (True)

The runlevel is changed by having a privileged user run telinit, which sends appropriate signals to init, telling it which runlevel to change to.

Week Fourteen AgendaLinux Signals are: Signal Name Number Description SIGHUP 1 Hangup (POSIX) SIGINT 2 Terminal interrupt (ANSI) SIGQUIT 3 Terminal quit (POSIX) SIGILL 4 Illegal instruction (ANSI) SIGTRAP 5 Trace trap (POSIX) SIGIOT 6 IOT Trap (4.2 BSD) SIGBUS 7 BUS error (4.2 BSD) SIGFPE 8 Floating point exception (ANSI) SIGKILL 9 Kill(can't be caught or ignored) (POSIX) SIGUSR1 10 User defined signal 1 (POSIX) SIGSEGV 11 Invalid memory segment access (ANSI) SIGUSR2 12 User defined signal 2 (POSIX)

Week Fourteen AgendaLinux Signals are: SIGPIPE 13 Write on a pipe with no reader, Broken pipe (POSIX) SIGALRM 14 Alarm clock (POSIX) SIGTERM 15 Termination (ANSI) SIGSTKFLT 16 Stack fault SIGCHLD 17 Child process has stopped or exited, changed (POSIX) SIGCONT 18 Continue executing, if stopped (POSIX) SIGSTOP 19 Stop executing(can't be caught or ignored) (POSIX) SIGTSTP 20 Terminal stop signal (POSIX) SIGTTIN 21 Background process trying to read, from TTY (POSIX)

Week Fourteen AgendaLinux Signals are: SIGTTOU 22 Background process trying to write, to TTY (POSIX) SIGURG 23 Urgent condition on socket (4.2 BSD) SIGXCPU 24 CPU limit exceeded (4.2 BSD) SIGXFSZ 25 File size limit exceeded (4.2 BSD) SIGVTALRM 26 Virtual alarm clock (4.2 BSD) SIGPROF 27 Profiling alarm clock (4.2 BSD) SIGWINCH 28 Window size change (4.3 BSD, Sun) SIGIO 29 I/O now possible (4.2 BSD) SIGPWR 30 Power failure restart (System V) Command to display signal value: kill –l SIGTERM

Week Fourteen AgendaLinux SignalsYou can specify the signal using either a number (such as 9) or a mane (such as SIGKILL).The signals you’re most likely to use are 1 (SIGHUP, which terminates interactive programs and causes many daemons to reread their configurationfiles), 9 (SIGKILL, which causes the process to exit without performing routine shutdown tasks), and 15 (SIGTERM, which causes the process to exit but allows it to close open files). If you don’t specify a signal, the default is 15 (SIGTERM).

The kill program will kill only those processes owned by the user who runs kill. The exception is if that user is root; the superuser may kill any user’s processes.

Week Fourteen AgendaLinux SignalsSignals can be passed to programs by the kernel even if you don’t use the kill command. For instance, when you log out of a session, the programs you started from that session are sent the SIGHUP signal, which causes them to terminate. If you want to run a program that will continue running even when you log out, you can launch it with the nohup program:

nohup program optionsThis command causes the program to ignore the SIGHUP signal. It can be handy if you want to launch certain small servers that may legitimately be run as ordinary users.

Week Fourteen AgendaQuestions and Issues

Your final exam status will be displayed on the Announcement page the same as the midterm exam.