So, the first example of the ls -ld command ( drwx-) means the entry is a directory in which the owner has read, write and execute permissions and no one else has any permissions. A dash ( -) in any entry means no permission for that operation. The third character of each set represents execute ( x) which allows running the file. The second character of each set represents write ( w) which allows changes to be made to the file, including deletion. The first character of each set represents read ( r) which allows read access to the file. The 'other' category encompasses everyone else and is usually called world, which I will use for the rest of this article. They are not generally used on UW Uniform Access systems), and the third set of three representing the 'other' permissions. The first set of three represent the owners permissions, the second set of three represent the group permissions (the use of group permissions varies from system to system. The rest of the characters are broken up into fields of three. The first character is what type of entry you're looking at, either d for directory or - for a plain file. Typing ls -ld at the host system prompt will show you the permissions of your home directory, with a string of 10 characters that should look something like drwx- or drwx-x-x. Or perhaps you've uploaded some software and you need to change the file permission so you can run it. It would be much better to have one person download the software and change the permissions so everyone on that system could access the file. If the file is large it would be a waste of resources to have everyone who wanted to use the software download their own copy. For example, let's say you've downloaded a piece of software you want to share with other people on your system. The chmod (CHange MODe) command is used to change permissions for a file or directory on a Unix machine.

Chmod execute permission