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chmod -R

Applies a change to a directory and everything inside it.

chmod -R mode dir walks the directory tree and applies the same change to every file and directory in it.

With a number that's usually wrong, because directories and files need different modes: chmod -R 755 marks every file executable, and chmod -R 644 takes the search bit off every directory, locking everyone out. Use a symbolic mode with capital X, or find.

Examples

chmod -R u+rwX,go+rX,go-w /var/www/site

755 for directories and 644 for files in one pass — capital X adds execute only to directories and files that are already executable

find /var/www/site -type d -exec chmod 755 {} +

directories only

find /var/www/site -type f -exec chmod 644 {} +

files only

chmod -R go-rwx ~/.ssh

a symbolic change is safe recursively: it only touches the bits it names

Good to know

  • There's no undo. Before a big recursive change, save the current modes: getfacl -R dir > perms.acl lets you restore them with setfacl --restore=perms.acl.
  • Never run chmod -R on / or a system directory. It breaks setuid programs like sudo, and ssh refuses keys whose permissions are too open.
  • GNU chmod changes the target of a symlink named on the command line, but ignores symlinks it meets while recursing.
  • "Permission denied" errors after deploys are usually an ownership problem. chown -R to the right user fixes them without loosening permissions.

Frequently asked questions

How do I chmod only directories, or only files?

Use find: find dir -type d -exec chmod 755 {} + for directories and find dir -type f -exec chmod 644 {} + for files. Or use capital X in one pass: chmod -R u+rwX,go+rX,go-w dir.

What does capital X mean in chmod?

Execute only where it makes sense: on directories, and on files that already have execute permission for someone. It lets one recursive command make directories searchable without making plain files executable.

Is chmod -R 777 ever a good idea?

No. It gives every user write access to every file in the tree and marks all of them executable. Fix the owner with chown, or use a shared group with mode 2775 for directories.

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