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Chapter 8 Working with Users and Groups 125
This command affects the permissions on files and folders created by programs that
respect the Mac OS X NSUmask settings. Programs should follow the value set for
NSUmask, but there is no guarantee that they will. Also, users can override their own
NSUmask setting at any time. The changes to the umask settings take effect at next
login.
Changing Permissions
Use the chmod tool to change permissions for an item.
$ chmod
securitygroup
changetype permission fileorfolder
To remove write access permission for group and others from the file myfile:
$ chmod go-w myfile
To add read and write access permission for group and others to files myfile1 and
myfile2:
$ chmod go+rw myfile1 myfile2
To add read, write, and execute permission for everyone to myfile1:
$ chmod ugo+rwx myfile1
See the chmod man page for more information.
Warning: Setting permissions to group, or all, will allow any private, or confidential
information in these folders to be visible to others. To prevent private files being
accessed, the user should create a folder and restrict the permissions.
Parameter Description
securitygroup
The person or group whose permission you are changing. Can be
any of the following:
 u - user
 g - group
 o - other
 all - all
changetype
Type of change. Whether you are adding or subtracting the
permission:
 “+” - add permission
 “-” - subtract permission
permission
The permission you are changing:
 r - read
 w - write
 x - execute
fileorfolder
The name of the file or folder to change.