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chmod Calculator Guide

About this tool

Convert between octal permissions and symbolic ones, toggling read, write and execute for owner, group and others. It shows the resulting chmod command and the rwxr-xr-x string side by side, so you can check one against the other before running anything.

Questions

What is the difference between 644 and 755?
644 gives the owner read and write and everyone else read, which is the normal choice for files. 755 adds execute for everyone, which is what directories and scripts need.
What does a leading digit mean?
In a full Unix permission number, the leading digit can hold setuid, setgid, and sticky bits. This calculator does not preserve or report that digit correctly. Check special bits using system tools before changing permissions.