User`s guide

Using Command-Line Tools 31

If you see a warning message about a “man in the middle attack” when you try to connect

using SSH, that means the RSA key ﬁngerprint on the server and your admin computer no

longer match. This can happen if you use command-line tools to administer a remote server,

establish an RSA key ﬁngerprint, and later change your SSH conﬁguration, perform a clean

install of system software, or start up from the Mac OS X Server CD.

To connect to the remote server again using SSH, you need to edit the entries

corresponding to the hosts (which can be stored by both name and IP number) in this

ﬁle: ~/.ssh/known_hosts. You can use TextEdit or another editor to ﬁnd the hostname

or IP address and then delete the key. The key is a long string that may wrap to several

lines. In TextEdit you can press the Control key and type K to delete the line, then delete

the blank line that it creates.

Standard UNIX Command-Line Tools

Mac OS X Server includes support for many basic UNIX command-line tools that you can use

to manage and set up servers. Information about three of these tools is provided here, but

you should read the man pages for each tool to fully understand how to use them.

Check Disks for Problems

fsck

fsck_hfs

To check for problems with disks locally, you can use Apple’s Disk First Aid application. To do

this from a remote admin computer, you need to log in using SSH and use these command-

line tools: fsck_hfs (for Mac OS Extended, or Hierarchical File System, formatted disks) or

fsck (for UNIX File System formatted disks).

You can only use these commands on unmounted volumes, so you can’t use them on the

volume the server is started from. Unmount volumes before you start.

1 Log in to the server as the root administrator.

LL2133.book Page 31 Friday, May 24, 2002 11:17 AM