Node.js - unable to save entire output of `git clone` command using child_process spawnSync

Question

What I want to do:

I am using Node.js to execute git clone command using child_process.spawnSync() and then save the output in a variable for later usage.

Example:

For example, I want to execute git clone https://github.com/octo-org/public-repo.git and save the resulting output in a variable:

Cloning into 'public-repo'...
remote: Enumerating objects: 3, done.
remote: Counting objects: 100% (3/3), done.
remote: Total 3 (delta 0), reused 0 (delta 0), pack-reused 0
Unpacking objects: 100% (3/3), done.

Failed Attempt 1: only able to save first line of output (not the entire output)

However, I am only able to save the first line of output (i.e., Cloning into 'public-repo'...) in a variable. Here is what I have so far:

const args = ["clone", "https://github.com/octo-org/public-repo.git"];
const child = require("child_process").spawnSync("git", args);
const output = `${child.stderr}`;
console.log(output); // only returns "Cloning into 'public-repo'..."

Failed Attempt 2: entire output is printed to console, but i need to save it in a variable

Also, I looked into inherit option of options.stdio. Although it prints the entire result (instead of just the first line), I need to save the result in a variable. So, options = { stdio: "inherit" } will print the full output, but I need to save the full output in a variable. Here is my code for that:

// this solution prints the full output
// but i need to save the full output in a variable

const args = ["clone", "https://github.com/octo-org/public-repo.git"];
const options = { stdio: "inherit" };
const child = require("child_process").spawnSync("git", args, options);

Failed Attempt 3: redirect output to file (>) only writes the first line

Someone suggested redirecting output to file (>), but this also results in only the first line of output (Cloning into 'public-repo'...) being written to readme.txt file

require("child_process").exec(
  "git clone https://github.com/octo-org/public-repo.git 2> readme.txt",
  { stdio: "inherit", shell: true },
  (error, stdout, stderror) => {}
);

Question:

How can I use Node.js Child Processes to save the entire git clone output in a variable? So far, I am only able to print/display the entire output (but not save it in a variable). Also, I am only able to save the first line of output (but not the entire output) after executing git clone command.

Do you think If you output all the result in a single file and then read the file with fs and input it into a variable is a better solution? — El.
– El., Commented Jul 19, 2019 at 21:12
It depends on OS for example for Linux: git clone https://github.com/octo-org/public-repo.git > readme.txt — El.
– El., Commented Jul 19, 2019 at 21:42
@El. I tried your suggestion git clone https://github.com/octo-org/public-repo.git > readme.txt using Node.js Child Processes and it only returns the first line (Cloning into 'public-repo'...). Your suggestion works fine if I manually type the command in the terminal, but not using Node.js child_process — kimbaudi
– kimbaudi, Commented Jul 19, 2019 at 22:38
edit: I meant to say I tried git clone https://github.com/octo-org/public-repo.git 2> readme.txt. Notice I am using 2> to redirect to stderr because git clone outputs to stderr even if status == 0 (i.e. success). — kimbaudi
– kimbaudi, Commented Jul 20, 2019 at 3:47

kimbaudi · Accepted Answer · 2019-07-20 03:54:24Z

4

Okay, so I figured out how to capture the entire output from executing git clone command by passing the --progress option to git clone (i.e., git clone --progress <some_remote_url>).

According to git clone documentation, we can pass --progress option to force progress status even if the stderr stream isn't directed to a terminal.

Since the progress status was directed at a terminal and I was spawning a child process that is not attached to a terminal, I could not capture the progress output.

So here is the updated Node.js code passing --progress option to capture the entire output of git config:

// adding --progress works

const args = [
  "clone",
  "https://github.com/octo-org/public-repo.git",
  "--progress"
];
const child = require("child_process").spawnSync("git", args);
console.log(`${child.stderr}`);

answered Jul 20, 2019 at 3:54

kimbaudi

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