child_process

exec

function exec(
  command: string,
  options?: {
    encoding?: string | BufferEncoding | null | 'buffer';
    cwd?: string;
    env?: NodeJS.ProcessEnv;
    shell?: string;
    timeout?: number;
    maxBuffer?: number;
    killSignal?: string;
    uid?: number;
    gid?: number;
    windowsHide?: boolean;
  }
): Observable<[stdout: string | Buffer, stderr: string | Buffer]>;

Spawns a shell then executes the command within that shell, buffering any generated output. The command string passed to the exec function is processed directly by the shell, and special characters (vary based on shell) need to be dealt with accordingly:

exec('"/path/to/test file/test.sh" arg1 arg2').subscribe();
// Double quotes are used so that the space in the path is not interpreted as
// a delimiter of multiple arguments.

exec('echo "The \\$HOME variable is $HOME"').subscribe();
// The $HOME variable is escaped in the first instance, but not in the second.

Never pass unsanitized user input to this function. Any input containing shell metacharacters may be used to trigger arbitrary command execution.

The stdout and stderr arguments passed to the stream will contain the stdout and stderr output of the child process. By default, Node.js will decode the output as UTF-8 and pass strings to the callback. The encoding option can be used to specify the character encoding used to decode the stdout and stderr output. If encoding is 'buffer', or an unrecognized character encoding, Buffer objects will be passed to the callback instead.

import { exec } from '@rxnode/child_process';

exec('cat *.js missing_file | wc -l').subscribe({
  next([stdout, stderr]) {
    console.log(`stdout: ${stdout}`);
    console.error(`stderr: ${stderr}`);
  },
  error(error) {
    console.error(`exec error: ${error}`);
  },
});

If timeout is greater than 0, the parent will send the signal identified by the killSignal property (the default is 'SIGTERM') if the child runs longer than timeout milliseconds.

Unlike the exec(3) POSIX system call, exec() does not replace the existing process and uses a shell to execute the command.

execFile

function execFile(
  file: string,
  args?: readonly string[],
  options?: {
    encoding?: string | null | BufferEncoding;
    cwd?: string;
    env?: NodeJS.ProcessEnv;
    timeout?: number;
    maxBuffer?: number;
    killSignal?: string;
    uid?: number;
    gid?: number;
    windowsHide?: boolean;
    windowsVerbatimArguments?: boolean;
    shell?: boolean | string;
  }
): Observable<[stdout: string | Buffer, stderr: string | Buffer]>;

The execFile() function is similar to exec() except that it does not spawn a shell by default. Rather, the specified executable file is spawned directly as a new process making it slightly more efficient than exec().

The same options as exec() are supported. Since a shell is not spawned, behaviors such as I/O redirection and file globbing are not supported.

import { execFile } from '@rxnode/child_process';

execFile('node', ['--version']).subscribe({
  next([stdout, stderr]) {
    console.log(stdout);
  },
  error(error) {
    console.error(`exec error: ${error}`);
  },
});

The stdout and stderr arguments passed to the stream will contain the stdout and stderr output of the child process. By default, Node.js will decode the output as UTF-8 and pass strings to the callback. The encoding option can be used to specify the character encoding used to decode the stdout and stderr output. If encoding is 'buffer', or an unrecognized character encoding, Buffer objects will be passed to the callback instead.

If the shell option is enabled, do not pass unsanitized user input to this function. Any input containing shell metacharacters may be used to trigger arbitrary command execution.