Chmod Calculator: Octal & Symbolic Permissions
Tick the permissions you want, or type an octal or symbolic mode, and get the matching chmod command. It also accepts ls -l output like -rwxr-xr-x.
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| Read | Write | Execute | |
|---|---|---|---|
| Owner (u) | |||
| Group (g) | |||
| Others (o) |
755 · rwxr-xr-x
chmod 755 file.txt
chmod -R 755 ./dir # recursive: careful, applies to files AND dirs
# Directories and files separately (the usual safe pattern)
find ./dir -type d -exec chmod 755 {} +
find ./dir -type f -exec chmod 644 {} +How octal permissions work
Each digit is a sum: read is 4, write is 2, execute is 1. The three digits are owner, group and others, so 754 means owner rwx (7), group r-x (5), others r-- (4). An optional leading fourth digit sets the special bits: 4 for setuid, 2 for setgid and 1 for the sticky bit, which is why /tmp is 1777.
On a directory, execute means "can enter" and read means "can list". That's why directories are usually 755 while files are 644, and why chmod -R 755 on a whole tree makes every file executable. Use the find pattern shown instead. If something still says "Permission denied", work through diagnosing Permission denied on Linux.
Questions people ask
What does chmod 755 mean?
The owner can read, write and execute (7), while the group and everyone else can read and execute (5). It's the standard mode for directories and executable scripts.
What does chmod 644 mean?
The owner can read and write (6), and the group and everyone else can only read (4). It's the usual mode for regular files such as configs and web content.
Is chmod 777 ever safe?
Almost never. 777 lets every user on the system modify or replace the file, which is a common path to privilege escalation. Fix ownership with chown, or grant group access, instead of opening permissions to everyone.