Chmod refers to change mode, a command for changing file access permissions in a UNIX-based operating system.
The chmod, or change mode, command allows an administrator to set or modify a file’s permissions. Every UNIX file has an owner user and an owner group attached to it, and every file has permissions associated with it. The permissions are as follows: read, write, or execute.
UNIX systems have many users. In this context, a user may refer to an individual or a system operation. UNIX identifies each user with a UID, and users may be organized into groups.
The syntax of the chmod command is:
chmod mode file
Example:
chmod 720 readme.txt
Each number in the mode parameter represents the permissions for a user or group of users:
Table 1 shows the eight numbers that can be used within the chmod parameter. The rwx column specifies read, write, and excecute access, offering a binary value for each operation. A "1" means "yes," a "0" means "no." If rwx reads 110, then that permission may read and write, but not excecute.
| # | Permission | rwx |
| 0 | none |
000 |
| 1 | execute only | 001 |
| 2 | write only | 010 |
| 3 | write and execute | 011 |
| 4 | read only | 100 |
| 5 | read and execute | 101 |
| 6 | read and write | 110 |
| 7 | read, write, and excecute | 111 |
Table 1. chmod mode parameters.
For example, if you set your directory permissions to 720, then your permissions would function as follows:
For 24-hour assistance any day of the year, contact our support team by email or through your Client Portal.
Our award-winning customer care team is here for you.
Contact Support
