UNIX file permissions

Unix file permissions can be expressed as three- or four-digit values; for example, 1644.

The first digit is interpreted as follows:

  • If the first digit is 1 (known in UNIX circles as the "Sticky bit"), it sets the link permission to directories or sets the "save-text" attribute for a file.
  • If the first digit is 2, it sets the group ID on execution.
  • If the first digit is 4, it sets the user ID on execution.

The second digit expresses Owner permissions; the third, Group permissions; the fourth, Other.

Three- and four-digit values are used in the WS_FTP log, in the message area, and by some system administrators and ISPs.

The table below shows how WS_FTP check box options correspond to the last three digits. The third column shows the possible values for Owner, Group, and Other as viewed in the ten-position value in the first column of a directory list for a UNIX site.

Selected options in WS_FTP

2nd, 3rd, or 4th digit

Permissions in directory list

none

0

---

Execute

1

--x

Write

2

-w-

Write, Execute

3

-wx

Read

4

r--

Read, Execute

5

r-x

Read, Write

6

rw-

Read, Write, Execute

7

rwx

In the directory list, the first position indicates whether the item is a file (-, s, S, or t) or directory (d), while positions two through ten show the permissions for Owner, Group, and Other.

If you attempt to change permissions, check the message area or the log to see if you were successful.