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HTML / CSS / JS

# View file permissions
ls -l /etc/passwd
# -rw-r--r-- 1 root root 2847 Apr  1 10:00 /etc/passwd
# ^          ^    ^    ^
# type+perms links owner group

# View permissions in octal
stat -c "%a %n" /etc/passwd
# 644 /etc/passwd

# Permission bit reference:
# r = 4, w = 2, x = 1
# rwx = 7 | rw- = 6 | r-x = 5 | r-- = 4 | -wx = 3 | -w- = 2 | --x = 1 | --- = 0

# Common permission patterns:
# 644  (-rw-r--r--)  regular files
# 755  (drwxr-xr-x)  directories & executables
# 600  (-rw-------)  private keys, sensitive files
# 700  (drwx------)  private directories
# 777  (drwxrwxrwx)  world-writable (avoid in production)

# Check permissions on several files
ls -l /etc/shadow /etc/sudoers /etc/ssh/ssh_host_rsa_key
# ---------- 1 root shadow  ...  /etc/shadow
# -r--r----- 1 root root   ...  /etc/sudoers
# ---------- 1 root root   ...  /etc/ssh/ssh_host_rsa_key

# Display all files in a dir with permissions
ls -la /etc/ | head -20

# Find world-writable files (security audit)
find /var/www -perm -002 -type f