1# param
2
3The param tool enables you to operate system parameters. It is valid only for standard-system devices.
4
5## Environment Setup
6
7* You have obtained the <!--Del-->[<!--DelEnd-->hdc tool<!--Del-->](../../device-dev/subsystems/subsys-toolchain-hdc-guide.md)<!--DelEnd--> to run hdc shell commands.
8* The device is properly connected.
9
10## param Commands
11
12| Command| Description|
13| ----------------- | ------------------------------------------ |
14| -h | Obtains the commands supported by param.|
15| ls [-r] [name] | Displays the information about the system parameter that matches the given name. If **-r** is carried, the information is obtained based on the parameter permission. If **-r** is not carried, the information is directly obtained.|
16| get [name] | Obtains the value of the system parameter with the given name. If no name is specified, the values of all system parameters are returned.|
17| set name value | Sets the value for the system parameter with the given name.|
18| wait name [value] [timeout] | Waits for the system parameter with the given name to match the specified value. Fuzzy match is supported. For example, * indicates any value, and **val*** indicates matching of only the first three val characters. **timeout** indicates the waiting time, in seconds. If it is not set, the default value 30s is used.|
19| save | Persistently saves the parameters to the workspace.|
20
21## -h
22
23* Obtains the commands supported by the param tool.
24
25  ```bash
26  param -h
27  ```
28
29## ls
30
31* Displays the information about the system parameter that matches the given name.
32
33  ```bash
34  param ls [-r] [name]
35  ```
36  **Example**<br>
37  ![ls-integrity](figures/param-ls-integrity.png)
38  ![ls-part](figures/param-ls-part.png)
39  ![ls](figures/param-ls.png)
40
41## get
42
43* Obtains the value of the system parameter with the given name.
44
45  ```bash
46  param get [name]
47  ```
48  **Example**<br>
49  ![get](figures/param-get.png)
50
51## set name value
52
53* Sets the value for the system parameter with the given name.
54
55  ```bash
56  param set name value
57  ```
58  **Example**<br>
59  ![set](figures/param-set.png)
60
61## wait name
62
63* Waits for the system parameter with the given name to match the specified value.
64
65  ```bash
66  param wait name [value] [timeout]
67  ```
68  **Example**<br>
69  ![wait](figures/param-wait.png)
70
71## save
72
73* Persistently saves the parameters to the workspace.
74
75  ```bash
76  param save
77  ```
78  **Example**<br>
79  ![save](figures/param-save.png)
80