Every web developer encounters this fundamental permission paradox at some point: should your web directory be owned by the FTP user for convenient file management, or by the Apache user for proper script execution? When you set ownership to the FTP user (typically vsftpd or proftpd), PHP scripts throw "Permission denied" errors during filesystem operations. But switching ownership to Apache (www-data or apache) locks out your FTP user from routine file operations.

This conflict stems from how Unix permissions and process ownership interact:

# Apache running as:
ps aux | grep apache
www-data  1234  0.0  1.2  /usr/sbin/apache2

# FTP user trying to modify files:
drwxr-xr-x 5 www-data www-data 4096 /var/www/html

The key insight: PHP scripts execute as the Apache user, while file uploads/modifications via FTP occur under the FTP user's identity.

Here's the professional approach using Linux ACLs (Access Control Lists):

# Install ACL utilities if needed
sudo apt-get install acl

# Set directory ownership to Apache
sudo chown -R www-data:www-data /var/www

# Grant FTP user group write permissions
sudo usermod -a -G www-data ftpuser

# Set ACL permissions recursively
sudo setfacl -R -m g:www-data:rwx /var/www
sudo setfacl -R -d -m g:www-data:rwx /var/www

For PHP applications, you might need to adjust the umask to ensure proper file creation:

// Add to your PHP script or php.ini
umask(0002); // Allows group write permissions

For WordPress or similar CMS:

# Special WP permissions
find /var/www/html -type d -exec chmod 775 {} \;
find /var/www/html -type f -exec chmod 664 {} \;

Another approach is to configure PHP-FPM to run scripts as the FTP user:

; In /etc/php/7.x/fpm/pool.d/www.conf
user = ftpuser
group = ftpuser

Then set directory ownership accordingly:

sudo chown -R ftpuser:ftpuser /var/www

Remember to:

• Never use 777 permissions
• Regularly audit permissions with ls -la
• Consider using SFTP instead of FTP
• Implement proper directory structure isolation

Every web developer working with LAMP stacks eventually faces this scenario: You need both FTP/SFTP access for manual file management and Apache execution privileges for PHP scripts, but these requirements seem mutually exclusive when it comes to directory ownership.

Let me break down the technical tension:

# Apache needs ownership for PHP file operations:
chown -R apache:apache /var/www/html

# FTP user needs ownership for manual edits:
chown -R ftpuser:ftpgroup /var/www/html

Neither solution works perfectly because each breaks the other's functionality.

Here's what worked for my production servers:

# Create a shared group
groupadd webdev

# Add both users to the group
usermod -a -G webdev apache
usermod -a -G webdev ftpuser

# Set directory ownership and permissions
chown -R ftpuser:webdev /var/www
chmod -R 2775 /var/www

The magic lies in:

1. The setgid bit (2) ensuring new files inherit the group

2. 775 permissions giving the group full access

For more complex environments, consider ACLs:

setfacl -R -m u:apache:rwx,d:u:apache:rwx /var/www
setfacl -R -m u:ftpuser:rwx,d:u:ftpuser:rwx /var/www
setfacl -R -m g:webdev:rwx,d:g:webdev:rwx /var/www

This maintains compatibility with both services while allowing more granular control.

Add this to your PHP scripts when dealing with file operations:

// Check and set permissions before file operations
if (!is_writable($filepath)) {
chmod($filepath, 0664);
chown($filepath, 'ftpuser');
chgrp($filepath, 'webdev');
}

Don't forget to configure your FTP server's umask:

# In vsftpd.conf
local_umask=002

This ensures newly uploaded files have correct group permissions by default.