Red Hat NETSCAPE MANAGEMENT SYSTEM 6.0 - CUSTOMIZATION User Manual download pdf (Page 259)

16.12 Ownership and Permissions 247

Beyond the ﬁrst item, in the following three sets, we’ll see one of the following:

r –ﬁle can be read

w –ﬁle can be written to

x –ﬁle can be executed (if it’saprogram)

When we see a dash in owner, group or others, it means that particular permission hasn’t been

granted.

Let’s look again at ﬁrst column of sneakers.txt and identify its permissions. (See Figure 16.17)

[billy@localhost billy]$ ls -l sneakers.txt

-rw-rw-r-- 1 billy billy 150 Mar 19 08:08 sneakers.txt

[billy@localhost billy]$

Figure 16.17: A closer view of permissions

The ﬁle’sowner,billy, has permission to read and write to the ﬁle; it’s not a program, so billy

doesn’t have permission to execute it. The group, billy, has permission to read and write to sneak-

ers.txt, as well. Similar to the program notation for owner billy,there’s no execute permission

for group billy.

In the last set, we can see that those who aren’t either the user billy or in the group called billy

can read the ﬁle, but can’t write to it or execute it.

We can use the chmod command to change a ﬁle’s permissions.

Let’s work a bit more on sneakers.txt to change the permissions with the chmod command.

The original ﬁle looks like this, with its initial permissions settings:

-rw-rw-r-- 1 billy billy 150 Mar 19 08:08 sneakers.txt

As long as we’re the owner of the ﬁle – or we’re logged into the root account – we can change

permissions in any combination of settings for the owner, group and others.

Right now, the owner (that’sus)andourgroup(whichisbilly) can read and write to the ﬁle.

Anyone outside of our group – for example, anyone in the adm group - can only read the ﬁle (r- -).

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Red Hat NETSCAPE MANAGEMENT SYSTEM 6.0 - CUSTOMIZATION User Manual Page 259