chmod / permissions calculator

Convert between octal, symbolic and checkbox Linux file permissions — and get the exact chmod command.

Toggle the read/write/execute boxes, type an octal value, or read the symbolic string — all three stay in sync, and you get the chmod command to run.

How Linux permissions work

Every file has three permission sets — for the owner, the group, and others — and each set has three bits: read (r), write (w) and execute (x). A symbolic listing like -rw-r--r-- reads left to right: type, then owner, group, other.

Octal notation

Octal	Symbolic	Means
`7`	rwx	read + write + execute
`6`	rw-	read + write
`5`	r-x	read + execute
`4`	r–	read only
`0`	—	no access

Common permission sets

Mode	Typical use
`644`	Regular files — owner edits, everyone reads
`755`	Directories and scripts — everyone can enter/run, owner writes
`600`	Private files (SSH keys, secrets) — owner only
`700`	Private directories — owner only
`777`	Everyone can do anything — almost always a mistake; avoid

chmod, chown and directories

chmod sets permissions; chown sets who owns the file. On a directory, the execute bit means “may enter”, not “may run”. Apply recursively with care using -R, and prefer find to set files and directories differently rather than blanket 777.

Frequently asked questions

What does 755 mean?

Owner has read, write and execute (7); group and others have read and execute (5, 5). It is the usual mode for directories and executable scripts.

Why is 777 dangerous?

It lets any user on the system read, modify and execute the file. On a web server that can turn an upload into a foothold. Grant the least access that works instead.

How do I set files and directories differently?

Use find: for example find . -type d -exec chmod 755 {} + and find . -type f -exec chmod 644 {} + to give directories 755 and files 644.

	r (4)	w (2)	x (1)
Owner
Group
Other