附录：各种信号及其用途
SignalDescriptionSignal number on Linux x86[1]SIGABRT Process aborted 6
SIGALRM Signal raised by alarm 14
SIGBUS Bus error: "access to undefined portion of memory object" 7
SIGCHLD Child process terminated, stopped (or continued*) 17
SIGCONT Continue if stopped 18
SIGFPE Floating point exception: "erroneous arithmetic operation" 8
SIGHUP Hangup 1
SIGILL Illegal instruction 4
SIGINT Interrupt 2
SIGKILL Kill (terminate immediately) 9
SIGPIPE Write to pipe with no one reading 13
SIGQUIT Quit and dump core 3
SIGSEGV Segmentation violation 11
SIGSTOP Stop executing temporarily 19
SIGTERM Termination (request to terminate) 15
SIGTSTP Terminal stop signal 20
SIGTTIN Background process attempting to read from tty ("in") 21
SIGTTOU Background process attempting to write to tty ("out") 22
SIGUSR1 User-defined 1 10
SIGUSR2 User-defined 2 12
SIGPOLL Pollable event 29
SIGPROF Profiling timer expired 27
SIGSYS Bad syscall 31
SIGTRAP Trace/breakpoint trap 5
SIGURG Urgent data available on socket 23
SIGVTALRM Signal raised by timer counting virtual time: "virtual timer expired" 26
SIGXCPU CPU time limit exceeded 24
SIGXFSZ File size limit exceeded 25