Learn Linux Shell Scripting - Fundamentals of Bash 4.4

chmod

Description	Change file mode bits. Can be specified as either rwx or octal mode.
Syntax	chmod [OPTION]... OCTAL-MODE FILE...
Practical uses	chmod -c: Like verbose but report only when a change is made. chmod -R: Change files and directories recursively. chmod --reference=RFILE: Copy the mode from a reference file.