X Pixmap

import magic
# Libmagic can identify XPM files by checking for the '/* XPM */' comment header
print(magic.from_file('icon.xpm', mime=True)) # Outputs 'image/x-xpixmap' or 'text/plain'

const fs = require('fs');
// Reading the first 9 bytes to check for the '/* XPM */' signature
const buffer = Buffer.alloc(9);
const fd = fs.openSync('icon.xpm', 'r');
fs.readSync(fd, buffer, 0, 9, 0);
fs.closeSync(fd);
const isXPM = buffer.toString('ascii') === '/* XPM */';
console.log('Is X Pixmap (XPM):', isXPM);

import (
    "bytes"
    "net/http"
)
// Native Go HTTP detection may return text/plain because XPM is valid C source code.
// Check directly for the /* XPM */ prefix:
// isXPM := bytes.HasPrefix(buf, []byte("/* XPM */"))

$mime = mime_content_type('icon.xpm');
echo $mime; // May return 'image/x-xpixmap', 'image/xpm', or 'text/plain' depending on the system's magic database rules.