The chmod Command

We use the chmod command to change the access mode of a file. This command comes in many flavors, but we'll be talking primarily about one of them.

chmod who=permissions filename

This gives “who” the specified permissions for a given filename.

Who

The “who” is a list of letters that specifies whom you’re going to be giving permissions to. These may be specified in any order.

Letter	Meaning
u	The user who owns the file (this means “you.”)
g	The group the file belongs to.
o	The other users
a	all of the above (an abbreviation for ugo)

Permissions

Of course, the permissions are the same letters that you see in the directory listing:

r	Permission to read the file.
w	Permission to write (or delete) the file.
x	Permission to execute the file, or, in the case of a directory, search it.

Note: Do not put blanks around the equal sign, or your command will not work!

<< Others’ Permissions

Index

Some examples >>