chmod Calculator
Compute Unix file permissions: toggle read/write/execute for user, group, others. Get numeric, symbolic, and full chmod commands.
chmod 755 file chmod u=rwx,go=rx file About this tool
Every file and directory on a Unix system has a permission set that decides who can read (r), write (w), and execute (x) it. These permissions are split into three groups: the owner, the group, and others. The chmod command changes them.
Permissions can be written two ways. The numeric form packs each group into one digit from 0–7: read=4, write=2, execute=1, summed. So 755 means "owner full, group and others can read and execute." The symbolic form spells it out: rwxr-xr-x. This calculator shows both, plus the exact chmod command to apply them.
Common values: 755 for executable scripts and web directories, 644 for regular files, 600 for private config files like SSH keys, and 777 (everyone full access — usually a mistake).
FAQ
What does chmod 755 mean? ›
The owner can read, write, and execute (7 = 4+2+1); the group and everyone else can read and execute (5 = 4+1) but not modify. This is the standard permission for programs and web directories.
What is the difference between 644 and 755? ›
644 lets the owner read and write while everyone else can only read; 755 adds execute permission for the owner plus read+execute for group and others. Use 644 for files and 755 for directories and executable scripts.
Why do directories need the execute bit? ›
On Unix the execute bit on a directory means "permission to enter" — to traverse it when looking up a file inside. Without it you cannot list the contents or access files even if you have read permission on them.
What is the symbolic form of 600? ›
rw-------. Only the owner can read and write; group and others have no access. This is the standard permission for SSH private keys.
How do I share a specific permission set? ›
Click the "Share link" button to copy a URL that encodes the current permissions (e.g. ?mode=755). Opening that link restores the exact permission set with all checkboxes and special bits in place.