4.
Setting Permissions
The following is a simple explanation
of file permissions in Unix. To list the access permissions of a file or
directory, telnet to your server, then:
cd directoryname
to change the directory until you are
either in the directory above the file you are interested in, or above the
directory you are checking.
Type: ls -l filename
and you will see what the current
permission settings are for that file, along with a bunch of other stuff.
Examples of using
chmod:
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People
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Permission
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u = the file's user
(you)
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r = read access
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g = the file's
group
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x = execute
access
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o = others
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w = write
access
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a = the user, the group, and
others
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To change permissions for a file named
filename.cgi, you need to chmod the file (change mode). For example, when you
type this:
chmod u=rwx,g=rx,o=rx filename.cgi
you've given:
read, execute, and
write access to the user (that's you)
read and execute access to the group
and
read and execute access to others
Some scripts will tell you to chmod 775
(for example). Doing the above is the same thing as typing chmod 775. You can
use either method with our Unix servers. Let me explain:
When using the numeric system, the code
for permissions is as follows:
r = 4 w = 2 x = 1 rwx = 7
The first 7 of our chmod775 tells Unix
to change the user's permissions to rxw (because r=4 + w=2 + x=1 adds up to 7.
The second 7 applies to the group, and the last number 5, refers to others
(4+1=5).
When doing an ls -l on the file, telnet
always shows the permissions this way:
-rwxr-xr-x
Ignore the first dash, then break up
the above into three groups of letters. If there's a dash where a letter should
be, it means that there is no permission for those people.
Remember: the first 3 apply to user,
the second 3 apply to group, and the third 3 apply to others.
Some FTP clients support changing
permissions in a more graphical way. If you have Fetch for the Mac, you have an
easy way to change permissions. Go to the file you want to change the
permissions on, and highlight it. Under the Remote menu, select Change
Permissions. A window will pop up showing the current permissions for the file
you had highlighted, as in Figure 3A below. Click on the boxes to change
permissions as needed.
Figure 3A
WS_FTP accomplishes the same task as
above. Just highlight the file you want to check, and right-click on it. A menu
will pop up, then select CHMOD. You will see the window below, as in Figure
3B.
Figure 3B
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