What CHMOD? File Permissions Calculator
Calculate chmod values and chmod strings from file permissions and vice versa. For more information please read the short tutorial "What is chmod?".
Download "What CHMOD?"
18th February 2009: a problem with downloading and running the apps should now be sorted. Let me know if there are still issues.
"What CHMOD?" can be downloaded as a standalone executable 'Flash Player 8 Projector File' - there is no need to install any Flash plugins/players!
Download the application using either the "Download Windows Version" or "Download Mac Version" button. Your browser should then start downloading the file (it may ask you where to save the file first). To use "What CHMOD?" just run (double-click) the downloaded file on your desktop.
| OS | Filesize | Download | Number of Downloads |
|---|---|---|---|
| Files have been scanned by antivirus software - but please do double-check! | |||
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1.58 MB | 3121 | |
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undetermined | 473 | |
Donate
This program is free to use, but a donation to help with bandwidth and development costs is appreciated. Just click on the PayPal "Donate" button for either UK Pounds Sterling (£) or US Dollars ($) - you can enter your own donation amount.
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| Thank you for your donation. | |
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JavaScript Version
Check the Read/Write/Execute boxes to calculate the chmod values and chmod string, or enter the chmod value to retrieve the Read/Write/Execute options. A javascript enabled browser is needed to use this feature.
If you would like to be able to enter either the file permissions (checkboxes), chmod values (e.g. 755) or chmod strings (e.g. rwxr-w-r-w), then you can download "What CHMOD?" as a standalone program where entering one field will dynamically alter the other two.
Instructions
What chmod? will be help you calculate chmod values and file permissions and vice versa.
- File Permissions to CHMOD Values/String:
- Select the various checkboxes in the "File Permissions Table" and see the chmod values and string change dynamically.
- CHMOD Values to File Permissions:
- Type in the numeric value in to the "CHMOD Values" boxes and press the "
What CHMOD?" button.
What is chmod?
CHMOD (change mode) is a Unix command that tells the server how much access it can grant to a file (permissions). There are three types of user: owner (you, includes the server), group (a specific group of people) and public (everybody else). Each type of user can have three levels of access: read (can view a file), write (can write and delete a file) and execute (can run a file/program).
You can set the individual permissions for each type of user. For example, you (owner) might want to read, write and execute "database.cgi", but you do not want strangers (public) to be able to update (or destroy) the database! So, we use chmod to set the permissions of the file so that anybody can read and execute (run) the database (assuming it's not secret), but only you can write to the database (i.e., update its contents).
When setting chmod values, you sometimes see a string of letters like rwxr-xr-x or a three digit number like 755. Both of these examples mean the same thing: the owner can read, write and execute a file, the group can read and execute a file, and the public can read and execute a file.
The string of letters correspond to the names of the file permissions (read, write, execute), whereas, each digit in the number sequence represents the sum of permissions for each type of user. That is because each permission has a numerical value: read = 4, write = 2 and execute = 1.
So, using our 755 example: the first digit (7) represents the owner, and is the sum of 4+2+1 (the maximum number you can have), which is read, write and execute. The next digit (5) represents the group, and is the sum of 4+1, which is read and execute. The last digit (also 5) represents the public, and is the sum of 4+1, again, read and execute.
