What is chmod?

chmod is a command in Unix and Linux systems used to change the file permissions of a file or directory. The name stands for "change mode."

Key Points:

• Permissions: It controls who can read, write, or execute a file. Permissions are set for three categories of users:
  • Owner: The user who owns the file.
  • Group: Users who are part of the file's group.
  • Others: All other users.

Usage:

chmod can be used in two ways:

1. Symbolic Notation: Uses letters to represent permissions.

   • Example: chmod u+x file.txt (adds execute permission for the owner).

2. Octal Notation: Uses numbers to represent permissions.

   • Example: chmod 755 file.txt (sets read, write, and execute for the owner, and read and execute for group and others).

Example Command:

chmod 644 myfile.txt

This command sets the permissions so that the owner can read and write, while the group and others can only read.

If you have any more questions or need further details, feel free to ask!