Definitely requires network access to build. Build script eventually returned -

script/build
Node: v12.16.3
Npm: v6.14.4
Python: v2.7.5
Installing script dependencies
npm ERR! Linux 3.10.0-1062.4.3.el7.x86_64 npm ERR! argv "/usr/bin/node" "/bin/npm" "--loglevel=error" "install"
npm ERR! node v6.17.1
npm ERR! npm v3.10.10
npm ERR! code ETIMEDOUT
npm ERR! errno ETIMEDOUT
npm ERR! syscall connect

npm ERR! network connect ETIMEDOUT 104.16.16.35:443 npm ERR! network This is most likely not a problem with npm itself npm ERR! network and is related to network connectivity.
npm ERR! network In most cases you are behind a proxy or have bad network settings.
npm ERR! network
npm ERR! network If you are behind a proxy, please make sure that the npm ERR! network 'proxy' config is set properly. See: 'npm help config'

npm ERR! Please include the following file with any support request:
npm ERR! /home/jgaer/atom-master/script/npm-debug.log
child_process.js:651
throw err;
^

Error: Command failed: npm --loglevel=error install npm ERR! Linux 3.10.0-1062.4.3.el7.x86_64 npm ERR! argv "/usr/bin/node" "/bin/npm" "--loglevel=error" "install"
npm ERR! node v6.17.1
npm ERR! npm v3.10.10
npm ERR! code ETIMEDOUT
npm ERR! errno ETIMEDOUT
npm ERR! syscall connect

npm ERR! network connect ETIMEDOUT 104.16.16.35:443 npm ERR! network This is most likely not a problem with npm itself npm ERR! network and is related to network connectivity.
npm ERR! network In most cases you are behind a proxy or have bad network settings.
npm ERR! network
npm ERR! network If you are behind a proxy, please make sure that the npm ERR! network 'proxy' config is set properly. See: 'npm help config'

npm ERR! Please include the following file with any support request:
npm ERR! /home/jgaer/atom-master/script/npm-debug.log

at checkExecSyncError (child_process.js:630:11) at Object.execFileSync (child_process.js:648:15) at module.exports (/home/jgaer/atom-master/script/lib/install-script-dependencies.js:12:16)
at Object. (/home/jgaer/atom-master/script/bootstrap:37:1)
at Module._compile (internal/modules/cjs/loader.js:1133:30)
at Object.Module._extensions..js (internal/modules/cjs/loader.js:1153:10)
at Module.load (internal/modules/cjs/loader.js:977:32)
at Function.Module._load (internal/modules/cjs/loader.js:877:14)
at Module.require (internal/modules/cjs/loader.js:1019:19)
at require (internal/modules/cjs/helpers.js:77:18) {
status: 1,
signal: null,
output: [
null,
,
<Buffer 6e 70 6d 20 45 52 52 21 20 4c 69 6e 75 78 20 33 2e 31 30 2e 30 2d 31 30 36 32 2e 34 2e 33 2e 65 6c 37 2e 78 38 36 5f 36 34 0a 6e 70 6d 20 45 52 52 21 ... 731 more bytes> ],
pid: 3888,
stdout: ,
stderr: <Buffer 6e 70 6d 20 45 52 52 21 20 4c 69 6e 75 78 20 33 2e 31 30 2e 30 2d 31 30 36 32 2e 34 2e 33 2e 65 6c 37 2e 78 38 36 5f 36 34 0a 6e 70 6d 20 45 52 52 21 ... 731 more bytes> }

I am seeing that the superstring (https://github.com/atom/superstring) dependency doesn't build on CentOS 7.

Looks like it's using newer c++ language features that are not supported with the old compiler toolchain on CentOS 7?

../src/core/text-buffer.cc: In constructor 'TextBuffer::Snapshot::Snapshot(TextBuffer&, TextBuffer::Layer&, TextBuffer::Layer&)':
../src/core/text-buffer.cc:1073:56: error: invalid initialization of non-const reference of type 'TextBuffer&' from an rvalue of type '<brace-enclosed initializer list>'
   : buffer{buffer}, layer{layer}, base_layer{base_layer} {}
                                                        ^
../src/core/text-buffer.cc:1073:56: error: invalid initialization of non-const reference of type 'TextBuffer::Layer&' from an rvalue of type '<brace-enclosed initializer list>'
../src/core/text-buffer.cc:1073:56: error: invalid initialization of non-const reference of type 'TextBuffer::Layer&' from an rvalue of type '<brace-enclosed initializer list>'
make: *** [Release/obj.target/superstring_core/src/core/text-buffer.o] Error 1
gyp ERR! build error 
gyp ERR! stack Error: `make` failed with exit code: 2
gyp ERR! stack     at ChildProcess.onExit (/root/atom/apm/node_modules/atom-package-manager/node_modules/npm/node_modules/node-gyp/lib/build.js:194:23)
gyp ERR! stack     at ChildProcess.emit (events.js:223:5)
gyp ERR! stack     at Process.ChildProcess._handle.onexit (internal/child_process.js:272:12)
gyp ERR! System Linux 5.4.0-74-generic
gyp ERR! command "/root/atom/apm/node_modules/atom-package-manager/bin/node" "/root/atom/apm/node_modules/atom-package-manager/node_modules/npm/node_modules/node-gyp/bin/node-gyp.js" "rebuild"
gyp ERR! cwd /root/atom/node_modules/superstring
gyp ERR! node -v v12.14.1
gyp ERR! node-gyp -v v5.1.0
gyp ERR! not ok 
npm ERR! code ELIFECYCLE
npm ERR! errno 1
npm ERR! [email protected] install: `node-gyp rebuild`
npm ERR! Exit status 1
npm ERR! 
npm ERR! Failed at the [email protected] install script.
npm ERR! This is probably not a problem with npm. There is likely additional logging output above.

npm ERR! A complete log of this run can be found in:
npm ERR!     /root/.atom/.apm/_logs/2021-06-23T13_07_04_066Z-debug.log

Although if you can get newer GCC/G++ (version 4.8.1 or newer) installed and running, the compilation error may go away?

• https://flight-manual.atom.io/hacking-atom/sections/hacking-on-atom-core/

  • If script/build exits with an error, you may need to install a newer C++ compiler with C++11:

• https://gcc.gnu.org/projects/cxx-status.html#cxx11

  • GCC 4.8.1 was the first feature-complete implementation of the 2011 C++ standard, previously known as C++0x.

I see GCC 4.8.5 is what is installed in my CentOS Docker container ... and it's still giving me that error? And it also fails with that error on Ubuntu 14.04 "Trusty" with Clang 5... 🤷 I'm not sure what it takes. I just know it builds on the current Ubuntu and Fedora distros, at least.

You must have git installed on your system.
Now, go to the folder where you want to have your Atom editor and then press right-click and then select the option Git bash Here. Now, fork the atom repo and then use the command git clone [email protected]:your-username/atom.git and replace your-username with your GitHub Username. Now, just do cd atom and after that, run script/bootstrap. It worked in my case at least.