How to change ownership of files and folders in Linux

Each Linux file and folder are assigned to an owner, a group, and other users; neither the owner nor member of the given group. To change the access permission for the files and folders, you can change the permission for each previously mentioned category. You can also change the permission of files and folders by changing their ownership, which is to assign them to a new owner or group.

The common way to change the ownership of files and folders in Linux is by using chown and chgrp. Both are command-line tools available in all Linux and other Unix-based operating systems such as macOS and the BSDs.

1. Launch terminal.
2. List existing users in the system.

   $ getent passwd
   root:x:0:0:root:/root:/bin/bash
   daemon:x:1:1:daemon:/usr/sbin:/usr/sbin/nologin
   bin:x:2:2:bin:/bin:/usr/sbin/nologin
   sys:x:3:3:sys:/dev:/usr/sbin/nologin
   sync:x:4:65534:sync:/bin:/bin/sync
   games:x:5:60:games:/usr/games:/usr/sbin/nologin
   man:x:6:12:man:/var/cache/man:/usr/sbin/nologin
   lp:x:7:7:lp:/var/spool/lpd:/usr/sbin/nologin
   mail:x:8:8:mail:/var/mail:/usr/sbin/nologin
   news:x:9:9:news:/var/spool/news:/usr/sbin/nologin
   uucp:x:10:10:uucp:/var/spool/uucp:/usr/sbin/nologin
   proxy:x:13:13:proxy:/bin:/usr/sbin/nologin
   www-data:x:33:33:www-data:/var/www:/usr/sbin/nologin
   backup:x:34:34:backup:/var/backups:/usr/sbin/nologin
   list:x:38:38:Mailing List Manager:/var/list:/usr/sbin/nologin
   irc:x:39:39:ircd:/var/run/ircd:/usr/sbin/nologin
   gnats:x:41:41:Gnats Bug-Reporting System (admin):/var/lib/gnats:/usr/sbin/nologin
   nobody:x:65534:65534:nobody:/nonexistent:/usr/sbin/nologin
   systemd-timesync:x:100:101:systemd Time Synchronization,,,:/run/systemd:/usr/sbin/nologin
   systemd-network:x:101:103:systemd Network Management,,,:/run/systemd:/usr/sbin/nologin
   systemd-resolve:x:102:104:systemd Resolver,,,:/run/systemd:/usr/sbin/nologin
   messagebus:x:103:106::/nonexistent:/usr/sbin/nologin
   syslog:x:104:110::/home/syslog:/usr/sbin/nologin
   _apt:x:105:65534::/nonexistent:/usr/sbin/nologin
   tss:x:106:111:TPM software stack,,,:/var/lib/tpm:/bin/false
   uuidd:x:107:114::/run/uuidd:/usr/sbin/nologin
   tcpdump:x:108:115::/nonexistent:/usr/sbin/nologin
   avahi-autoipd:x:109:117:Avahi autoip daemon,,,:/var/lib/avahi-autoipd:/usr/sbin/nologin
   usbmux:x:110:46:usbmux daemon,,,:/var/lib/usbmux:/usr/sbin/nologin
   rtkit:x:111:118:RealtimeKit,,,:/proc:/usr/sbin/nologin
   dnsmasq:x:112:65534:dnsmasq,,,:/var/lib/misc:/usr/sbin/nologin
   avahi:x:113:120:Avahi mDNS daemon,,,:/run/avahi-daemon:/usr/sbin/nologin
   cups-pk-helper:x:114:121:user for cups-pk-helper service,,,:/home/cups-pk-helper:/usr/sbin/nologin
   speech-dispatcher:x:115:29:Speech Dispatcher,,,:/run/speech-dispatcher:/bin/false
   kernoops:x:116:65534:Kernel Oops Tracking Daemon,,,:/:/usr/sbin/nologin
   saned:x:117:123::/var/lib/saned:/usr/sbin/nologin
   nm-openvpn:x:118:124:NetworkManager OpenVPN,,,:/var/lib/openvpn/chroot:/usr/sbin/nologin
   whoopsie:x:119:125::/nonexistent:/bin/false
   colord:x:120:126:colord colour management daemon,,,:/var/lib/colord:/usr/sbin/nologin
   sssd:x:121:127:SSSD system user,,,:/var/lib/sss:/usr/sbin/nologin
   geoclue:x:122:128::/var/lib/geoclue:/usr/sbin/nologin
   pulse:x:123:129:PulseAudio daemon,,,:/var/run/pulse:/usr/sbin/nologin
   hplip:x:124:7:HPLIP system user,,,:/run/hplip:/bin/false
   gnome-initial-setup:x:125:65534::/run/gnome-initial-setup/:/bin/false
   gdm:x:126:131:Gnome Display Manager:/var/lib/gdm3:/bin/false
   user:x:1000:1000:user,,,:/home/user:/bin/bash
   systemd-coredump:x:999:999:systemd Core Dumper:/:/usr/sbin/nologin
   sshd:x:127:65534::/run/sshd:/usr/sbin/nologin
   shakir:x:1001:1001:shakir,,,:/home/shakir:/bin/bash

3. List existing groups in the system.

   $ getent group
   root:x:0:
   daemon:x:1:
   bin:x:2:
   sys:x:3:
   adm:x:4:syslog,user
   tty:x:5:
   disk:x:6:
   lp:x:7:
   mail:x:8:
   news:x:9:
   uucp:x:10:
   man:x:12:
   proxy:x:13:
   kmem:x:15:
   dialout:x:20:
   fax:x:21:
   voice:x:22:
   cdrom:x:24:user
   floppy:x:25:
   tape:x:26:
   sudo:x:27:user,shakir
   audio:x:29:pulse
   dip:x:30:user
   www-data:x:33:
   backup:x:34:
   operator:x:37:
   list:x:38:
   irc:x:39:
   src:x:40:
   gnats:x:41:
   shadow:x:42:
   utmp:x:43:
   video:x:44:
   sasl:x:45:
   plugdev:x:46:user
   staff:x:50:
   games:x:60:
   users:x:100:
   nogroup:x:65534:
   systemd-timesync:x:101:
   systemd-journal:x:102:
   systemd-network:x:103:
   systemd-resolve:x:104:
   crontab:x:105:
   messagebus:x:106:
   input:x:107:
   kvm:x:108:
   render:x:109:
   syslog:x:110:
   tss:x:111:
   bluetooth:x:112:
   ssl-cert:x:113:
   uuidd:x:114:
   tcpdump:x:115:
   ssh:x:116:
   avahi-autoipd:x:117:
   rtkit:x:118:
   netdev:x:119:
   avahi:x:120:
   lpadmin:x:121:user
   scanner:x:122:saned
   saned:x:123:
   nm-openvpn:x:124:
   whoopsie:x:125:
   colord:x:126:
   sssd:x:127:
   geoclue:x:128:
   pulse:x:129:
   pulse-access:x:130:
   gdm:x:131:
   lxd:x:132:user
   user:x:1000:
   sambashare:x:133:user
   systemd-coredump:x:999:
   shakir:x:1001:

4. Check current owner and group of file or folder.

   $ stat -c "%U:%G" /var/www/html/index.html
   root:root
5. Change owner of file based on the list of system users.

   $ sudo chown www-data /var/www/html/index.html

6. Check current owner and group of file to confirm.

   $ stat -c "%U:%G" /var/www/html/index.html
   www-data:root

7. Change group of file based on the list of system groups.

   $ sudo chgrp www-data /var/www/html/index.html

8. Change both owner and group of a directory.

   $ sudo chown www-data:www-data /var/www/html/

9. Change owner and group using wildcard.

   $ sudo chown www-data:www-data /var/www/html/*
10. Change owner and group recursively for all files and folders.

    $ sudo chown -R www-data:www-data /var/www/html/*

11. Check owner and group for all files and folders.

    $ ls -l /var/www/html/
    total 20
    drwxr-xr-x 2 www-data www-data  4096 Jan  24 09:58 css
    -rw-r--r-- 1 www-data www-data 10918 Jan  23 19:57 index.html
    drwxr-xr-x 2 www-data www-data  4096 Jan  24 09:57 js