Chmod Permissions Calculator: What It Does
Calculates Linux file permission modes between octal numbers (e.g. 755), symbolic notation (rwxr-xr-x), and interactive checkboxes for Owner, Group, and Others. It includes SUID, SGID, and Sticky bits.
Example
755-rwxr-xr-xMaps octal values 7 (rwx), 5 (r-x), and 5 (r-x) to standard Unix permission bits.
How to Use
- Toggle read (r), write (w), and execute (x) checkboxes for user, group, and public.
- Or enter an octal number like 644 to calculate symbolic flags.
- Copy the resulting chmod command to execute in your terminal.
Limitations
- Covers standard POSIX permission flags; advanced ACLs (setfacl) require custom shell commands.
- Special bits (SUID, SGID) behave differently on directories versus executable binaries.
Frequently Asked Questions
What do the numbers 4, 2, and 1 represent in chmod octal notation?
Read (r) has a binary weight of 4, write (w) has a weight of 2, and execute (x) has a weight of 1. Their sum represents the permission mode.
What is the function of the sticky bit (e.g. in mode 1777 on /tmp)?
The sticky bit prevents users from deleting or renaming files in a shared directory unless they are the file owner or root.
Command-Line Equivalent
chmod 755 script.shGrant read, write, and execute permissions to owner and read/execute to others.
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