Use chmod 755 to make a script or directory usable by everyone, while only the owner can modify it. For example, an executable maintenance script may need read and execute access for all users. Do not apply it to files containing secrets, because others can read the contents.
How chmod 755 works on a real system
chmod 755 is one of the most common permission settings for executables and directories. In practice, it gives the owner full control, while everyone else can read and run the item but not change it. That makes it a good fit for a shared utility script, a web server directory listing, or any file that should be usable without being editable by other users.
The numeric mode is easier to understand when you split it into three parts: owner, group, and others. The first digit, 7, means read, write, and execute for the owner. The two 5s mean read and execute for group members and all other users. For a directory, execute means the ability to enter or traverse it, so 755 is often used for shared folders that should be browsable but not writable by everyone.
A practical example is a maintenance script stored at /usr/local/bin/cleanup.sh. If the script belongs to an administrator, chmod 755 lets that admin edit it while allowing other users or automated jobs to run it. The same logic applies to a deployment helper, a backup wrapper, or any approved command that must be callable by others but only maintained by one owner.
When 755 is appropriate, and when it is not
755 is appropriate when the file or directory is meant to be broadly accessible but not broadly modifiable. That is why it is common for scripts, command-line tools, and static web directories. It preserves usability without granting write access to everyone who can reach the system.
It is not appropriate for content that includes secrets, credentials, private keys, token files, or other sensitive material. If you apply 755 to a confidential file, other users can read it, which defeats the point of restricting ownership. Even when the file itself is not sensitive, treat any directory that contains sensitive material carefully, because directory traversal rights can expose filenames, structure, and adjacent resources.
For directories, 755 is especially useful when you want users to list and access files but not add, remove, or rename them. For files, the same mode is usually best reserved for trusted code or documentation, not private operational data. If a file should only be readable by the owner, a more restrictive mode is usually the safer choice.
Reading 755 in everyday operational terms
When you see chmod 755 in a build script, server bootstrap file, or runbook, read it as a permission boundary rather than a security guarantee. It says the owner can manage the asset, while others can use it in a limited way. That is helpful for standard tooling, but it does not protect confidential content by itself.
The key operational question is whether broad read and execute access matches the asset’s purpose. If the answer is yes, 755 is often sensible. If the asset contains anything that should remain private, the permissions need to be tighter, and the surrounding directory structure should be reviewed as well.
Standards & Framework Alignment
This section maps relevant standards and security frameworks to the operational risks and controls described in this guidance.
CIS Controls v8 and NIST SP 800-53 Rev 5 set the technical controls, while ISO/IEC 27001:2022 defines the regulatory obligations.
| Framework | Control / Reference | Relevance |
|---|---|---|
| CIS Controls v8 | CIS-6 — Access Control Management | File permissions are a basic access-control decision. |
| Recommendation — Limit read and execute access to the users who need it. | ||
| NIST SP 800-53 Rev 5 | AC-6 — Least Privilege | 755 grants broad but bounded access and should follow least privilege. |
| Recommendation — Assign only the permissions required for use, not modification. | ||
| ISO/IEC 27001:2022 | A.5.15 — Access control | The example is an access-control configuration for a file or directory. |
| Recommendation — Define and enforce file permissions according to business need. | ||
Practitioner Guidance
What to verify: Check whether the item is meant to be executed or traversed by multiple users, and confirm that it contains no sensitive data before choosing 755. For a script, also confirm that the script path and any files it references do not widen access unintentionally.
Common mistake: Teams often treat 755 as a default safe setting for any file that “needs to work,” but that is only true for non-sensitive executables and directories. If the asset stores secrets or private operational data, 755 is usually too open.
Practitioner takeaway: Use 755 for shared use, not shared trust, it is a convenience setting for executables and directories, and it becomes a liability the moment confidentiality matters.