1# sem 2 3 4## Command Function 5 6This command is used to query information about kernel semaphores. 7 8 9## Syntax 10 11sem [_ID__ / fulldata_] 12 13 14## Parameters 15 16**Table 1** Parameter description 17 18| Parameter| Description| Value Range| 19| -------- | -------- | -------- | 20| ID | Specifies the semaphore ID.| [0, 1023] or [0x0, 0x3FF]| 21| fulldata | Displays information about all semaphores in use. <br/>The displayed information includes **SemID**, **Count**, **Original Count**, **Creator TaskEntry**, and **Last Access Time**. | N/A | 22 23 24## Usage Guidelines 25 26- If no parameter is specified, this command displays the semaphore IDs and the number of times that each semaphore is used. 27 28- If **ID** is specified, the use of the specified semaphore is displayed. 29 30- The **fulldata** parameter depends on **LOSCFG_DEBUG_SEMAPHORE**. Before using this parameter, set **Enable Semaphore Debugging** to **Yes** on **menuconfig**. 31 **Debug** ---> **Enable a Debug Version** ---> **Enable Debug LiteOS Kernel Resource** ---> E**nable Semaphore Debugging** 32 33 34## Example 35 36- Run **sem**. 37 38- Configure **LOSCFG_DEBUG_SEMAPHORE** and run **sem fulldata**. 39 40 41## Output 42 43Example 1: brief semaphore information 44 45``` 46OHOS # sem 47 SemID Count 48 ---------- ----- 49 0x00000000 1 50 SemID Count 51 ---------- ----- 52 0x00000001 0 53 SemID Count 54 ---------- ----- 55 0x00000002 0 56 SemID Count 57 ---------- ----- 58 0x00000003 1 59 SemID Count 60 ---------- ----- 61 0x00000004 0 62 SemID Count 63 ---------- ----- 64 0x00000005 1 65 SemID Count 66 ---------- ----- 67 0x00000006 0 68``` 69 70**Table 2** Output description 71 72| Parameter| Description| 73| -------- | -------- | 74| SemID | Semaphore ID.| 75| Count | Number of times that the semaphore is used.| 76 77> **NOTE**<br> 78> The **ID** value can be in decimal or hexadecimal format. 79> 80> When **ID** is a value within [0, 1023], semaphore information of the specified ID is displayed. If the specified semaphore is not used, a message is displayed to inform you of this case. For other values, a message is displayed indicating that the parameter is incorrect. 81 82Example 2: detailed semaphore information 83 84``` 85OHOS # sem fulldata 86Used Semaphore List: 87 SemID Count OriginalCount Creator(TaskEntry) LastAccessTime 88 ------ ------ ------------- ------------------ -------------- 89 0xb 0x0 0x0 0x404978fc 0xa1 90 0xc 0x0 0x0 0x404978fc 0xa1 91 0xd 0x0 0x0 0x404978fc 0x12c 92 0x10 0x0 0x0 0x404978fc 0x195 93 0xf 0x0 0x0 0x404978fc 0x195 94 0x11 0x0 0x0 0x4041a998 0x1d5 95 0x15 0x0 0x0 0x404978fc 0x273 96 0x14 0x0 0x0 0x404978fc 0x273 97 0x18 0x0 0x0 0x404978fc 0x352 98 0x17 0x0 0x0 0x404978fc 0x352 99 0x16 0x0 0x0 0x404978fc 0x352 100 0x1d 0x1 0x1 0x404978fc 0x385 101 0x1e 0x1 0x1 0x404978fc 0x388 102 0x1f 0x1 0x1 0x404978fc 0x38d 103 0x20 0x1 0x1 0x404978fc 0x38f 104 0x21 0x1 0x1 0x404978fc 0x392 105 0x3d 0x1 0x1 0x404978fc 0x395 106 0x3b 0x1 0x1 0x404978fc 0x395 107 0x3c 0x1 0x1 0x404978fc 0x395 108 0x39 0x1 0x1 0x404978fc 0x395 109 0x3a 0x1 0x1 0x404978fc 0x395 110 0x33 0x1 0x1 0x404978fc 0x395 111 0x35 0x1 0x1 0x404978fc 0x395 112 0x34 0x1 0x1 0x404978fc 0x395 113 0x38 0x1 0x1 0x404978fc 0x395 114``` 115 116**Table 3** Output description 117 118| Parameter| Description| 119| -------- | -------- | 120| SemID | Semaphore ID.| 121| Count | Number of times that the semaphore is used.| 122| OriginalCount | Original count of the semaphore.| 123| Creator | Address of the entry function of the thread used to create the semaphore.| 124| LastAccessTime | Last time when the semaphore was accessed.| 125