1 -*- mode: outline; coding: utf-8 -*-

     2 

     3 * Send signal to process.

     4 

     5   $ kill -s NAME PID

     6 

     7 Under C you can use kill(2) system call which will send the specified signal

     8 to the process, if permissions allow, or raise(3) library function, which

     9 sends the specified signal to the current process.

    10 

    11 * List of signals.

    12 

    13   $ kill --list

    14   $ kill -l      # short variant

    15 

    16 See

    17 

    18   http://en.wikipedia.org/wiki/Unix_signals

    19 

    20 ** SIGHUP 1.

    21 

    22 Hangup. Type: notification, can be handled.

    23 

    24 Sent when assigned to process terminal closed.

    25 

    26 nohup(1) utility used as a wrapper to start a program and make it immune to

    27 SIGHUP.

    28 

    29 The default action on POSIX-compliant systems is an abnormal termination.

    30 

    31 Demon used this signal as commant to reread config file.

    32 

    33 ** SIGINT 2

    34 

    35 Interrupt. Ctrl-C. Type: control, can be handled.

    36 

    37 Signal sent to a process by its controlling terminal when a user wishes to

    38 interrupt the process.

    39 

    40 By default, this causes the process to terminate.

    41 

    42 ** SIGQUIT 3.

    43 

    44 Quit. Ctrl-\. Type: control.

    45 

    46 Signal sent to a process by its controlling terminal when the user requests

    47 that the process dump core.

    48 

    49 By default, this causes the process to terminate and produce a memory core dump.

    50 

    51 Java dump thread traces to stdout.

    52 

    53 ** SIGILL 4.

    54 

    55 Illegal instruction. Type: exception, can not be handled.

    56 

    57 Signal sent to a process when it attempts to execute a malformed, unknown, or

    58 privileged instruction.

    59 

    60 ** SIGTRAP 5.

    61 

    62 Trace trap. Type: debug, can be handled.

    63 

    64 Signal sent to a process when a condition arises that a debugger has requested

    65 to be informed of.

    66 

    67 By default this causes abnormal termination of the process.

    68 

    69 ** SIGABRT 6.

    70 

    71 Type: control, can be handled.

    72 

    73 Signal sent to a computer program to tell it to abort, ie terminate.

    74 

    75 SIGABRT is sent by the process to itself when it calls the abort libc

    76 function. It is used when an assertion fails.

    77 

    78 By default this causes abnormal termination of the process.

    79 

    80 ** SIGEMT 7.

    81 

    82 Emt instruction.

    83 

    84 ** SIGFPE 8.

    85 

    86 Floating point exception. Type: exception, can be handled.

    87 

    88 Signal sent to a process when it performs an erroneous arithmetic operation

    89 (like division by zero).

    90 

    91 By default cause a core dump and a program exit.

    92 

    93 ** SIGKILL 9.

    94 

    95 Kill. Type: control, can not be handled.

    96 

    97 Signal sent to a process to cause it to terminate immediately.

    98 

    99 Zombie processes cannot be killed since they are already dead and waiting for

   100 their parent processes to reap them.

   101 

   102 Processes that are in the blocked state will not die until they wake up again.

   103 

   104 ** SIGBUS 10.

   105 

   106 Bus error. Type: exception, can not be handled.

   107 

   108 Signal sent to a process when it causes a bus error.

   109 

   110 By default this causes abnormal termination of the process.

   111 

   112 ** SIGSEGV 11.

   113 

   114 Segmentation violation. Type: exception.

   115 

   116 Signal sent to a process when it makes an invalid memory reference, or

   117 segmentation fault.

   118 

   119 By default cause a core dump and a program exit.

   120 

   121 ** SIGSYS 12.

   122 

   123 Bad argument to system call. Type: exception.

   124 

   125 By default this causes abnormal termination of the process.

   126 

   127 ** SIGPIPE 13.

   128 

   129 Write on a pipe with no one to read it. Type: notification.

   130 

   131 Signal sent to a process when it attempts to write to a pipe without a process

   132 connected to the other end.

   133 

   134 This causes the process to terminate, which is convenient when constructing

   135 shell pipelines.

   136 

   137 ** SIGALRM 14.

   138 

   139 Alarm clock. Type: notification.

   140 

   141 Signal sent to a process when a time limit has elapsed.

   142 

   143 By default this causes abnormal termination of the process.

   144 

   145 ** SIGTERM 15.

   146 

   147 Software termination signal. Type: control.

   148 

   149 Signal sent to a process to request its termination.

   150 

   151 It causes the termination of a process, but unlike the SIGKILL signal, it can

   152 be caught and interpreted (or ignored) by the process.

   153 

   154 SIGTERM is akin to asking a process to terminate nicely, allowing cleanup and

   155 closure of files. For this reason, on many Unix systems during shutdown, init

   156 issues SIGTERM to all processes that are not essential to powering off, waits

   157 a few seconds, and then issues SIGKILL to forcibly terminate any such

   158 processes that remain.

   159 

   160 By default kill(1) send to process SIGTERM signal.

   161 

   162 ** SIGURG 16.

   163 

   164 Urgent condition on IO channel. Type: notification.

   165 

   166 By default this signal ignored.

   167 

   168 ** SIGSTOP 17.

   169 

   170 Signal sent to a process to stop it for later resumption. Type: control.

   171 

   172 SIGSTOP cannot be caught or ignored.

   173 

   174 Usually SIGSTOP and SIGCONT are used for job control in the Unix shell.

   175 

   176 ** SIGTSTP 18.

   177 

   178 Stop signal from tty. Ctrl-Z. Type: control.

   179 

   180 By default, this causes the process to suspend execution.

   181 

   182 ** SIGCONT 19.

   183 

   184 Continue a stopped process. Type: control.

   185 

   186 Signal sent to restart a process previously paused by the SIGSTOP or SIGTSTP

   187 signal.

   188 

   189 ** SIGCHLD 20.

   190 

   191 To parent on child stop or exit. Type: notification.

   192 

   193 By default the signal is simply ignored. In C:

   194 

   195   signal(SIGCHLD, SIG_IGN);

   196 

   197 Parent can invoke wait(1) otherwise children stay zombie.

   198 

   199 ** SIGTTIN 21.

   200 

   201 Signal sent to a process when it attempts to read from the tty while in the

   202 background.

   203 

   204 Daemons do not have controlling terminals and should never receive this

   205 signal.

   206 

   207 By default this causes suspends of the process.

   208 

   209 ** SIGTTOU 22.

   210 

   211 Signal sent to a process when it attempts to write to the tty while in the

   212 background.

   213 

   214 Daemons do not have controlling terminals and should never receive this

   215 signal.

   216 

   217 By default this causes suspends of the process.

   218 

   219 ** SIGPOLL 23.

   220 

   221 System V name for SIGIO. Type: notification.

   222 

   223 Signal sent to a process when an asynchronous I/O event occurs.

   224 

   225 By default this causes abnormal termination of the process.

   226 

   227 ** SIGXCPU 24.

   228 

   229 Exceeded CPU time limit. Type: notification.

   230 

   231 By default this causes abnormal termination of the process.

   232 

   233 ** SIGXFSZ 25.

   234 

   235 Exceeded file size limit as determined by the ulimit system call and shell

   236 builtin. Type: notification.

   237 

   238 By default this causes abnormal termination of the process.

   239 

   240 ** SIGVTALRM 26.

   241 

   242 Virtual time alarm. Type: notification.

   243 

   244 Signal sent to a process when a time limit has elapsed.

   245 

   246 By default this causes abnormal termination of the process.

   247 

   248 ** SIGPROF 27.

   249 

   250 Profiling time alarm. Type: debug.

   251 

   252 Signal sent to a process when the profiling timer expires.

   253 

   254 By default this causes abnormal termination of the process.

   255 

   256 ** SIGWINCH 28.

   257 

   258 Window changed. Type: notification.

   259 

   260 Signal sent to a process when its controlling terminal changes size.

   261 

   262 By default this signal ignored.

   263 

   264 ** SIGLOST 29.

   265 

   266 Signal sent to process when a file lock is lost. This may occur, for example,

   267 when an NFS server reboots and forgets about a file lock.

   268 

   269 By default this causes abnormal termination of the process.

   270 

   271 ** SIGUSR1 30.

   272 

   273 User defined signal 1. Type: user defined.

   274 

   275 By default this causes abnormal termination of the process.

   276 

   277 ** SIGUSR2 31.

   278 

   279 User defined signal 2. Type: user defined.

   280 

   281 By default this causes abnormal termination of the process.