Red Hat RHCSARHCE 7 Cert Guide（七）

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1.it is easy to recognize the kernel processes because they have a name that is between square brackets.
2.ps aux | grep dd(pgrep dd):pgrep dd to get a list of all PIDs that have a name containing the string dd.
3.Use nice if you want to start a process with an adjusted priority.Use renice to change the priority for
        a currently active process. Alternatively,
        you can use the r command from the top utility to change the priority of a currently
        running process.
4.When using nice or renice to adjust process priority, you can select from values ranging from -20 to 19
(Do not set process priority to -20; it risks blocking other processes from getting served.)
5.nice -n 5 dd if=/dev/zero of=/dev/null & starts an infinite I/O-intensive job
  renice -n 10 -p 1234
6.man 7 signal for a complete overview of all the available signals
  ■ The signal SIGTERM (15) is used to ask a process to stop.
  ■ The signal SIGKILL (9) is used to force a process to stop.
  ■ The SIGHUP (1) signal is used to hang up a process. The effect is that the
        process will reread its configuration files, which makes this a useful signal to
        use after making modifications to a process configuration file.
7.Use kill -l to show a list of available signals that can be used with kill
8.The pkill command is a bit easier to use because it takes the name rather than the PID of the process as an argument
9.Using killall enables you to terminate all these processes simultaneously.       
10.enables you to cancel a current interactive shell job(CTRL + D 类似于exit)