What chmod 775 means
The owner and group digits are both 7, combining read (4), write (2), and execute (1). The other-user digit is 5, combining read and execute without write. A directory appears as drwxrwxr-x: its owner and assigned group can list, enter, and change entries, while everyone else can list and traverse but cannot create or remove entries.
On a regular file, 775 also grants execute permission to the owner, group, and other users. That is appropriate only when the file is meant to be executable. The common 775 use case is a directory; ordinary shared data files usually need a mode without execute bits.
Shared project and deployment directories
A development team can use 775 when several trusted accounts need to update the same project directory. A deployment user and a CI service can likewise share a group so either can publish artifacts without making the directory writable by every account on the host. Group ownership is what determines who receives the middle digit.
Set and verify the directory group before relying on 775. New entries may inherit each creator's primary group unless the directory uses an appropriate setgid workflow, commonly represented by a leading 2 in a four-digit mode. Test file creation from each participating account instead of assuming the parent mode alone guarantees lasting collaboration.
775 compared with 755
chmod 755 grants the same read and traverse access to the group and other users but reserves write permission for the owner. It fits a directory maintained by one deployment account. Mode 775 adds group write permission, which is the specific capability a multi-user team needs.
Do not add group write access just to suppress a permission error. Confirm which process needs to create, rename, or delete entries, place only that account in the assigned group, and check parent-directory ownership. A controlled identity model is safer and easier to audit than an oversized group.
Security boundaries for a writable group
Every member of the assigned group can change the directory. On a source tree or deployment path, one compromised group account may replace content used by other members or by a service. Review group membership, avoid mixing unrelated applications, and do not use 775 when the directory contents must remain private from other users.
Files stored inside a shared directory need their own modes. A group-editable data file can use chmod 660 without receiving an execute bit, while executable team scripts may need a different mode. Directory permission does not automatically make every existing file group-writable.