Understanding File Permissions:
File permissions in Unix-like systems determine who can read, write, or execute a file. They are represented as a combination of three groups: user (u), group (g), and others (o).
-rwxr-xr--
r stands for read permission.
w stands for write permission.
x stands for execute permission.
chmod
chmod: Change file permissions.
chmod 755 filename
touch testfile
ls -l testfile
# Change the file permissions to make it executable by the owner and readable by everyone:
chmod 744 testfile
ls -l testfile
# Change the file permissions using symbolic notation:
chmod u+x,g+r,o=r testfile
ls -l testfile
Explain
Explanation of chmod u+x,g+r,o=r testfile
The chmod command is used to change the permissions of a file or directory. The syntax of the command includes specifying the users (user, group, others), the operation (add, remove, set), and the permissions (read, write, execute).
u stands for "user" (the owner of the file).
g stands for "group" (the group to which the file belongs).
o stands for "others" (everyone else).
- means adding a permission.
= means setting a permission explicitly.
r stands for "read" permission.
w stands for "write" permission.
x stands for "execute" permission.
Command Breakdown:
u+x: Add execute permission for the user (file owner).
g+r: Add read permission for the group.
o=r: Set read permission for others (removes any other permissions for others).
Chown
chown: Change file owner and group.
chown [owner][:group] file
# Change the owner of testfile to yourusername:
chown $USER testfile
# > -rwxr--r-- 1 zhentianwan staff 0 May 19 10:35 testfile
# Change the owner and group of testfile:
chown $USER:Staff testfile