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I have the following script which executes a shell command:
#!/usr/bin/env node
const { execSync } = require('child_process');
try {
const data = execSync(
'yarn licenses generate-disclaimer --prod',
{ encoding: 'utf8', maxBuffer: 50 * 1024 * 1024 }
);
console.log(data.length);
return true;
} catch (error) {
console.error(`Failed to generate disclaimer: ${error.message}`);
return false;
}
data is a Buffer containing stdout of the child process. As I understand, the way to convert it to a string is to use the .toString() method, but in my case the string is incomplete. The command I am trying to execute is supposed to produce ~500 KB of data, but buffer.length is 43741 (that's ~43 KB).
The problem is probably that yarn licenses output contains some special characters which result in the buffer being incomplete. If I replace the command with printf "%0.s-" {1..500000}, the buffer is complete.
I am using the latest node version (8.7.0).
Any thoughts/suggestions?
EDIT: Appending | tr "\0" "\n" to the command increases the buffer size to ~122 KB, so @YaroslavAdmin is definitely looking in the right direction. The result is still incomplete though. How do I make sure all special characters are escaped?
901
child_process.exec() : spawns a shell and runs a command within that shell, passing the stdout and stderr to a callback function when complete.
Usually, Node. js allows single-threaded, non-blocking performance but running a single thread in a CPU cannot handle increasing workload hence the child_process module can be used to spawn child processes. The child processes communicate with each other using a built-in messaging system.
The spawn function launches a command in a new process and we can use it to pass that command any arguments. For example, here's code to spawn a new process that will execute the pwd command. const { spawn } = require('child_process'); const child = spawn('pwd');
The exec() function in Node. js creates a new shell process and executes a command in that shell. The output of the command is kept in a buffer in memory, which you can accept via a callback function passed into exec() .
Add .toString() after execSync.
const data = execSync(
'yarn licenses generate-disclaimer --prod',
{ encoding: 'utf8', maxBuffer: 50 * 1024 * 1024 }
).toString(); // <<<<<<<<<<<<
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