chmod / Permission Calculator

The chmod calculator opens on owner read, write, and exec, with group and other missing write. That state is octal 755 and the symbolic form rwxr-xr-x.

The opening 755

Each row has Read, Write, and Exec. Read is 4, write is 2, and exec is 1. Owner starts with all three, which is 7. Group starts with read and exec, which is 5. Other starts the same way, which is 5. The octal field therefore shows 755. The symbolic field shows rwxr-xr-x. The command line shows chmod 755 filename. Copy command puts that exact command on the clipboard and the button label changes to Copied. Typing a different three-digit octal from 0 through 7 moves the checkboxes. A digit above 7 is ignored and the boxes stay where they were. Two digits do not update the boxes.

What the three digits leave out

There is no setuid bit, no setgid bit, and no sticky bit. The form is the common three-digit mode only. A fourth digit is cut off because the octal field keeps three characters. Turning every box off produces 000 and the symbolic form of nine dashes. Owner read and write, with group and other read only, is 644 and rw-r--r--. The page does not change a file on your disk. It only builds the command text. The filename in that command is the word filename. Replace it after you copy. There is no recursive flag and no reference to a directory.

How to check 644

Leave the page as it opens. Octal should read 755 and symbolic should read rwxr-xr-x. Clear Write on owner, and clear Exec on group and other. Octal should read 644 and symbolic should read rw-r--r--. Type 755 back into the octal field and the original boxes should return. Type 8 as one of the three digits and the boxes should not move. Type only 75 and the boxes should not move, because the field applies a value only when it has three digits and each digit is 0 through 7. Copy command should place chmod, the current octal, and the word filename on the clipboard.

The checkboxes stay in the tab

The bit math runs in this browser. The checkboxes are not uploaded. Closing the tab returns the next visit to 755. Nothing is stored. The command always ends with the word filename. Copy command is the only button, and it changes to Copied after a successful copy. There is no download. 000 is nine dashes. 755 is rwxr-xr-x. 644 is rw-r--r--. A digit from 8 to 9 does not rewrite the rows. Setuid, setgid, and the sticky bit are not on this form. The page does not touch a file on disk. Copy command writes chmod, a space, the three digits, a space, and the word filename. 755 is the state the form opens on. 000 is every checkbox clear.