Convert Linux file permissions between octal, symbolic and chmod notation instantly.
Linux file permissions can be expressed as a 9-character symbolic string (owner, group, others — each a read/write/execute triplet) or as a 3-digit octal number. Each octal digit sums read (4), write (2) and execute (1) for that class. This calculator parses either format and converts to the other, plus a breakdown by owner, group and others. A fourth leading octal digit represents the setuid/setgid/sticky bits.
Octal digit from permissions
digit = 4×read + 2×write + 1×execute
754 breaks down as owner=7 (rwx, full access), group=5 (r-x, read and execute), others=4 (r--, read only). In symbolic form that is rwxr-xr--.
Symbolic notation spells out permissions as letters (r, w, x) for owner, group and others in a 9-character string. Octal notation compresses each triplet into a single digit 0-7 by summing 4 (read) + 2 (write) + 1 (execute).
A lowercase t in the execute position of 'others' means the sticky bit is set and execute is also set. An uppercase T means the sticky bit is set but execute is not. The sticky bit on a directory restricts file deletion to the file's owner.
Yes. A 4-digit mode's leading digit encodes setuid (4), setgid (2) and sticky (1) special bits; the remaining three digits are the normal owner/group/others permissions.