# 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 \[0, 64\].