Obtaining Process Information
NOTE The initial APIs of this module are supported since API version 7. Newly added APIs will be marked with a superscript to indicate their earliest API version.
Modules to Import
import process from '@ohos.process';
Attributes
System capability: SystemCapability.Utils.Lang
Name | Type | Readable | Writable | Description |
---|---|---|---|---|
egid | number | Yes | No | Effective group identifier (EGID) of a process. This is a system API and cannot be called by third-party applications. |
euid | number | Yes | No | Effective user identifier (EUID) of a process. This is a system API and cannot be called by third-party applications. |
gid | number | Yes | No | Group identifier (GID) of a process. This is a system API and cannot be called by third-party applications. |
uid | number | Yes | No | User identifier (UID) of a process. |
groups | number[] | Yes | No | Array with supplementary group IDs. This is a system API and cannot be called by third-party applications. |
pid | number | Yes | No | Process ID (PID) of a process. |
ppid | number | Yes | No | Parent process ID (PPID) of a process. This is a system API and cannot be called by third-party applications. |
tid8+ | number | Yes | No | Thread ID (TID) of a process. |
ChildProcess
Allows a process to obtain the standard input and output of its child processes, send signals, and close its child processes.
Attributes
System capability: SystemCapability.Utils.Lang
Name | Type | Readable | Writable | Description |
---|---|---|---|---|
pid | number | Yes | No | PID of the child process. This is a system API and cannot be called by third-party applications. |
ppid | number | Yes | No | PPID of the child process. This is a system API and cannot be called by third-party applications. |
exitCode | number | Yes | No | Exit code of the child process. This is a system API and cannot be called by third-party applications. |
killed | boolean | Yes | No | Whether the parent process successfully sends a signal to the child process to terminate it. This is a system API and cannot be called by third-party applications. |
wait
wait(): Promise<number>
Waits until the child process ends. This method uses a promise to return the exit code of the child process.
This is a system API and cannot be called by third-party applications.
System capability: SystemCapability.Utils.Lang
Return value
Type | Description |
---|---|
Promise<number> | Promise used to return the exit code of the child process. |
Example
var child = process.runCmd('ls');
var result = child.wait();
result.then(val=>{
console.log("result = " + val);
})
getOutput
getOutput(): Promise<Uint8Array>
Obtains the standard output of the child process.
This is a system API and cannot be called by third-party applications.
System capability: SystemCapability.Utils.Lang
Return value
Type | Description |
---|---|
Promise<Uint8Array> | Promise used to return the standard output in a Uint8Array. |
Example
var child = process.runCmd('ls');
var result = child.wait();
child.getOutput.then(val=>{
console.log("child.getOutput = " + val);
})
getErrorOutput
getErrorOutput(): Promise<Uint8Array>
Obtains the standard error output of the child process.
This is a system API and cannot be called by third-party applications.
System capability: SystemCapability.Utils.Lang
Return value
Type | Description |
---|---|
Promise<Uint8Array> | Promise used to return the standard error output in a Uint8Array. |
Example
var child = process.runCmd('madir test.text');
var result = child.wait();
child.getErrorOutput.then(val=>{
console.log("child.getErrorOutput= " + val);
})
close
close(): void
Closes the child process in running.
This is a system API and cannot be called by third-party applications.
System capability: SystemCapability.Utils.Lang
Example
var child = process.runCmd('sleep 5; ls');
child.close();
kill
kill(signal: number | string): void
Sends a signal to the specified child process to terminate it.
This is a system API and cannot be called by third-party applications.
System capability: SystemCapability.Utils.Lang
Parameters
Name | Type | Mandatory | Description |
---|---|---|---|
signal | number | string | Yes | Number or string to send. |
Example
var child = process.runCmd('sleep 5; ls');
child.kill(9);
process.isIsolatedProcess8+
isIsolatedProcess(): boolean
Checks whether this process is isolated.
System capability: SystemCapability.Utils.Lang
Return value
Type | Description |
---|---|
boolean | Returns true if the process is isolated; returns false otherwise. |
Example
var result = process.isIsolatedProcess();
process.isAppUid8+
isAppUid(v: number): boolean
Checks whether a UID belongs to this app.
System capability: SystemCapability.Utils.Lang
Parameters
Name | Type | Mandatory | Description |
---|---|---|---|
v | number | Yes | UID. |
Return value
Type | Description |
---|---|
boolean | Returns true if the UID is the app's UID; returns false otherwise. |
Example
var result = process.isAppUid(688);
process.is64Bit8+
is64Bit(): boolean
Checks whether this process is running in a 64-bit environment.
System capability: SystemCapability.Utils.Lang
Return value
Type | Description |
---|---|
boolean | Returns true if the process is running in a 64-bit environment; returns false otherwise. |
Example
var ressult = process.is64Bit();
process.getUidForName8+
getUidForName(v: string): number
Obtains the process UID based on the process name.
System capability: SystemCapability.Utils.Lang
Parameters
Name | Type | Mandatory | Description |
---|---|---|---|
v | string | Yes | Name of a process. |
Return value
Type | Description |
---|---|
number | Process UID. |
Example
var pres = process.getUidForName("tool")
process.getThreadPriority8+
getThreadPriority(v: number): number
Obtains the thread priority based on the specified TID.
System capability: SystemCapability.Utils.Lang
Parameters
Name | Type | Mandatory | Description |
---|---|---|---|
v | number | Yes | TID. |
Return value
Type | Description |
---|---|
number | Priority of the thread. |
Example
var tid = process.getTid();
var pres = process.getThreadPriority(tid);
process.getStartRealtime8+
getStartRealtime(): number
Obtains the duration, in milliseconds, from the time the system starts to the time the process starts.
System capability: SystemCapability.Utils.Lang
Return value
Type | Description |
---|---|
number | Duration obtained. |
Example
var realtime = process.getStartRealtime();
process.getPastCpuTime8+
getPastCpuTime(): number
Obtains the CPU time (in milliseconds) from the time the process starts to the current time.
System capability: SystemCapability.Utils.Lang
Return value
Type | Description |
---|---|
number | CPU time obtained. |
Example
var result = process.getPastCpuTime() ;
process.getSystemConfig8+
getSystemConfig(name: number): number
Obtains the system configuration.
System capability: SystemCapability.Utils.Lang
Parameters
Name | Type | Mandatory | Description |
---|---|---|---|
name | number | Yes | System configuration parameter name. |
Return value
Type | Description |
---|---|
number | System configuration obtained. |
Example
var _SC_ARG_MAX = 0
var pres = process.getSystemConfig(_SC_ARG_MAX)
process.getEnvironmentVar8+
getEnvironmentVar(name: string): string
Obtains the value of an environment variable.
System capability: SystemCapability.Utils.Lang
Parameters
Name | Type | Mandatory | Description |
---|---|---|---|
name | string | Yes | Environment variable name. |
Return value
Type | Description |
---|---|
string | Value of the environment variable. |
Example
var pres = process.getEnvironmentVar("PATH")
process.runCmd
runCmd(command: string, options?: { timeout : number, killSignal : number | string, maxBuffer : number }): ChildProcess
Forks a new process to run a shell command and returns the ChildProcess object.
This is a system API and cannot be called by third-party applications.
System capability: SystemCapability.Utils.Lang
Parameters
Name | Type | Mandatory | Description |
---|---|---|---|
command | string | Yes | Shell command to run. |
options | Object | No | Related parameters. |
Table 1 options
Name | Type | Mandatory | Description |
---|---|---|---|
timeout | number | No | Maximum running time (in ms) of the child process. When the running time of the child process exceeds the value of this parameter, the parent process sends a killSignal to the child process to terminate it. The default value is 0. |
killSignal | number | string | No | Signal sent to the child process when the running time of a child process exceeds the timeout period. The default value is SIGTERM. |
maxBuffer | number | No | Maximum buffer size for the standard input and output of the child process. When the size is exceeded, the child process will be terminated. The default value is 1024 * 1024. |
Return value
Type | Description |
---|---|
ChildProcess | ChildProcess object. |
Example
var child = process.runCmd('ls', { maxBuffer : 2 });
var result = child.wait();
child.getOutput.then(val=>{
console.log("child.getOutput = " + val);
})
process.abort
abort(): void
Aborts a process and generates a core file. This method will cause a process to exit immediately. Exercise caution when using this method.
System capability: SystemCapability.Utils.Lang
Example
process.abort();
process.on
on(type: string, listener: EventListener): void
Stores the events triggered by the user.
This is a system API and cannot be called by third-party applications.
System capability: SystemCapability.Utils.Lang
Parameters
Name | Type | Mandatory | Description |
---|---|---|---|
type | string | Yes | Type of the events to store. |
listener | EventListener | Yes | Callback invoked to return the event. |
Table 2 EventListener
Name | Description |
---|---|
EventListener = (evt: Object) => void | Event to store. |
Example
process.on("data", (e)=>{
console.log("data callback");
})
process.off
off(type: string): boolean
Deletes the event stored by the user.
This is a system API and cannot be called by third-party applications.
System capability: SystemCapability.Utils.Lang
Parameters
Name | Type | Mandatory | Description |
---|---|---|---|
type | string | Yes | Type of the event to delete. |
Return value
Type | Description |
---|---|
boolean | Returns true if the event is deleted; returns false otherwise. |
Example
process.on("data", (e)=>{
console.log("data callback");
})
var result = process.off("data");
process.exit
exit(code: number): void
Terminates this process.
Exercise caution when using this API.
System capability: SystemCapability.Utils.Lang
Parameters
Name | Type | Mandatory | Description |
---|---|---|---|
code | number | Yes | Exit code of the process. |
Example
process.exit(0);
process.cwd
cwd(): string
Obtains the working directory of this process.
This is a system API and cannot be called by third-party applications.
System capability: SystemCapability.Utils.Lang
Example
var path = process.cwd();
process.chdir
chdir(dir: string): void
Changes the working directory of this process.
This is a system API and cannot be called by third-party applications.
System capability: SystemCapability.Utils.Lang
Parameters
Name | Type | Mandatory | Description |
---|---|---|---|
dir | string | Yes | Path |
Example
process.chdir('/system');
process.uptime
uptime(): number
Obtains the running time of this process.
System capability: SystemCapability.Utils.Lang
Return value
Type | Description |
---|---|
number | Running time of the process, in seconds. |
Example
var time = process.uptime();
process.kill
kill(signal: number, pid: number): boolean
Sends a signal to the specified process to terminate it.
System capability: SystemCapability.Utils.Lang
Parameters
Name | Type | Mandatory | Description |
---|---|---|---|
pid | number | Yes | PID of the process, to which the signal will be sent. |
signal | number | Yes | Signal to send. |
Return value
Type | Description |
---|---|
boolean | Returns true if the signal is sent successfully; returns false otherwise. |
Example
var pres = process.pid
var result = that.kill(28, pres)