chmod 775 rwxrwxr-x

chmod 775 (rwxrwxr-x): the owner can read, write and execute, the group read, write and execute, others read and execute. Commands and umask.

Octal: 775 (also written 0775)
Symbolic: rwxrwxr-x
ls -l shows: -rwxrwxr-x for a file, drwxrwxr-x for a directory
chmod letters: u=rwx,g=rwx,o=rx

Who can do what

Class	Digit	Bits	On a file	On a directory
Owner (u)	7	`rwx`	Read the contents, change or empty the contents and run it as a program	List the names inside, create, delete and rename entries and enter it and open files by name
Group (g)	7	`rwx`	Read the contents, change or empty the contents and run it as a program	List the names inside, create, delete and rename entries and enter it and open files by name
Others (o)	5	`r-x`	Read the contents and run it as a program	List the names inside and enter it and open files by name

Each digit adds read (4), write (2) and execute (1). Deleting or renaming a file depends on write and execute on the directory that holds it, not on the file's own mode. Root bypasses read and write checks.

Typical uses

The owner and the group have full access, others can list and enter. New directories get it under umask 002, and it is common for shared web roots where a deploy group writes.

Security notes

The group can write, so check who is in the group; adding a user to it gives them write access.
Every account on the machine can read it, so keep passwords, keys and tokens out of anything with this mode.

Commands

Numeric
chmod 775 file
Symbolic
chmod u=rwx,g=rwx,o=rx file
Check the result
stat -c '%a %A %n' file
Directories only, recursively
find /path -type d -exec chmod 775 {} +

Avoid chmod -R 775 on a tree that holds files as well as folders: it makes every file executable. Use the find command above for directories and a file mode such as 664 for the files.

The umask that gives 775

umask 002: new directories are created as 775 (and files as 664)

Programs create files with 666 and directories with 777, and the umask removes bits from those. A umask never adds execute to a new file, and it cannot set setuid, setgid or the sticky bit.

Its file counterpart is chmod 664 (rw-rw-r--).

Other common modes

Work out any other mode in the chmod calculator