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What is chmod 755?
Chmod 755 is a command used to change the mode (permissions) of a file or directory on machines running Unix-like operating systems, including Linux, macOS, and BSD. In this command, the “755” represents the permission settings for the file or directory as follows:
- 7 Indicates read, write, and execute (rwx) permissions for the owner.
- 5 Indicates read and execute (rx) permissions for the group.
- 5 Indicates read and execute (rx) permissions for others.
The chmod 755 command is commonly used for scripts or executable files that need to be run by users, but only the owner can modify them.
Techopedia Explains the chmod 755 Meaning
The meaning of chmod 755 is to change permission settings so a file cannot be modified by anyone other than the owner. This command, used on Unix-like operating systems, ensures only the owner has permission to read, write, and execute the file but gives members of the group and other users permission to read and execute the file.
chmod 755 vs. chown 755
Chmod and chown are two different commands.
chmod 755 Command Examples
A common example is directory permissions on a web server where files need to be accessible and executable by the server process or visitors to the website.
For example, a directory named “public_html” contains files that users visiting your website access. In this scenario, you want to ensure only the owner can modify or delete files in the directory while providing all other users with read and execute permissions only.
The command used in this example is: chmod 755 public_html.
chmod 755 Pros and Cons
Pros
- Owner has full control over the file or directory (read, write, and execute permissions).
- Other users can execute files within the directory for broader, controlled access.
- Suitable for web servers where files need to be accessible and executable by the server process.
Cons
- Group members and others with write permissions elsewhere could inadvertently modify/delete files.
- Limited options may not be suitable for all access control scenarios.
- Owner is responsible to ensure permissions are set correctly.
The Bottom Line
The chmod 755 definition is permission settings that provide a balanced approach to access control while being specific about read, write, and execute permissions for the owner, group, and others. This makes it suitable for web servers or scenarios where multiple users need to access and execute files.
In some situations where a higher level of security is required, chmod 644 (removes execute access for the group and others) or chmod 600 (read and write access to the owner) might be more appropriate.
