kill

Command Function

This command is used to send a signal to a specified process.

Syntax

kill [-l [signo] | -s signo | -signo] pid...

Parameters

Table 1 Parameter description

Parameter	Description	Value Range
--help	Displays the parameters supported by the kill command.	N/A
-l	Lists the names and numbers of signals.	N/A
-s	Sends signals	N/A
signo	Specifies the signal number.	[1,30]
pid	Specifies the process ID.	[1,MAX_INT]

NOTICE: The value range of signo is [0, 64]. The recommended value range is [1, 30], and other values in the value range are reserved.

Usage

The signo and pid parameters are mandatory.
The pid value range varies depending on the system configuration. For example, if the maximum pid value supported by the system is 256, this value range is [1-256].

Example

Query the process list before killing process 42.

OHOS:/$ ps
  allCpu(%):    4.67 sys,  195.33 idle
  PID  PPID PGID       UID  Status VirtualMem ShareMem PhysicalMem CPUUSE10s  PName
    1    -1    1         0 Pending   0x33b000  0xbb000     0x4db02      0.0   init
    2    -1    2         0 Pending   0xdabc08        0    0xdabc08      1.14  KProcess
    3     1    3         7 Pending   0x72e000 0x1a3000    0x1d24c2      0.0   foundation
    4     1    4         8 Pending   0x362000  0xbb000     0x5c6ff      0.0   bundle_daemon
    5     1    5         1 Pending   0xdfa000 0x2e7000    0x1484f0      0.0   appspawn
    6     1    6         0 Pending   0x688000 0x137000    0x11bca0      0.0   media_server
    7     1    7         0 Pending   0x9d2000 0x103000     0xa1cdf      0.88  wms_server
    8     1    8         2 Pending   0x1f5000  0x48000     0x47dc2      0.2   mksh
   12     1   12         0 Pending   0x4d4000 0x112000     0xe0882      0.0   deviceauth_service
   13     1   13         0 Pending   0x34f000  0xbd000     0x51799      0.0   sensor_service
   14     1   14         2 Pending   0x34e000  0xb3000     0x52184      0.0   ai_server
   15     1   15         0 Pending   0x61f000 0x13b000    0x168071      0.45  softbus_server
   42     8   42         2 Pending   0x1c1000  0x3a000     0x1106a      0.9   test_demo
   43     8   43         2 Running   0x1d7000  0x3a000     0x1e577      0.0   toybox

Send signal 9 (the default action of SIGKILL is to immediately terminate the process) to process 42 test_demo (a user-mode process). Then, check the current process list. The commands kill -s 9 42 and kill -9 42 have the same effect.

OHOS:/$ kill -s 9 42
OHOS:/$
[1] + Killed               ./nfs/test_demo
OHOS:/$ ps
  allCpu(%):    4.73 sys,  195.27 idle
  PID  PPID PGID       UID  Status VirtualMem ShareMem PhysicalMem CPUUSE10s  PName
    1    -1    1         0 Pending   0x33b000  0xbb000     0x4e01c      0.0   init
    2    -1    2         0 Pending   0xda5fa4        0    0xda5fa4      1.14  KProcess
    3     1    3         7 Pending   0x72e000 0x1a3000    0x1d29dc      0.0   foundation
    4     1    4         8 Pending   0x362000  0xbb000     0x5cc19      0.0   bundle_daemon
    5     1    5         1 Pending   0xdfa000 0x2e7000    0x148a0a      0.0   appspawn
    6     1    6         0 Pending   0x688000 0x137000    0x11c1ba      0.0   media_server
    7     1    7         0 Pending   0x9d2000 0x103000     0xa21f9      0.89  wms_server
    8     1    8         2 Pending   0x1f5000  0x48000     0x482dc      0.2   mksh
   12     1   12         0 Pending   0x4d4000 0x112000     0xe0d9c      0.0   deviceauth_service
   13     1   13         0 Pending   0x34f000  0xbd000     0x51cb3      0.0   sensor_service
   14     1   14         2 Pending   0x34e000  0xb3000     0x5269e      0.0   ai_server
   15     1   15         0 Pending   0x61f000 0x13b000    0x16858b      0.51  softbus_server
   45     8   45         2 Running   0x1d7000  0x3a000     0x1e9f5      0.0   toybox

Run the kill -100 31 command.

Output

Example 1: The signal is successfully sent to process 42.

OHOS:/$ kill -s 9 42
OHOS:/$
[1] + Killed               ./nfs/test_demo

Process 42 is killed.

Example 2: The signal fails to be sent to process 31.

OHOS:/$ kill -100 31
kill: Unknown signal '(null)'

Unknown signal '(null)' is displayed because the signo value 100 exceeds the value range [0, 64].