NEXTSTEP In Focus, Winter 1994 (Volume 4, Issue 1). 
Copyright ã1994 by NeXT Computer, Inc.  All Rights Reserved.

TIPS & TECHNIQUES

Measuring Local Disk Space

System administrators often want to find how much space is available on just the local disks, without also checking imported file systems.  

There's an infrequently used argument to the UNIX df command that helps with this: the -t flag with an argument specifying the type of the file system to check. Values of the argument to -t can be of any valid file system type, like those used in /etc/fstab or as arguments to or output from the UNIX mount command.

Figure 1 shows three examples of how to use this option. 

Figure 1:  Examples of running df with the -t flag

	sabre [~]-412% 	df -t 4.3 
	Filesystem            kbytes    used   avail capacity  Mounted on
	/dev/sd0b             498935  405012   44029    90%    /NeXT-3.0
	/dev/sd0a             500015  372758   77255    83%    /
	/dev/fd0a               1231     905     326    74%    /SneakerNet
	sabre [~]-413% 	df -i -t 4.3
	Filesystem             iused   ifree  %iused  Mounted on
	/dev/sd0b              23102   83394    22%   /NeXT-3.0
	/dev/sd0a              17075   89421    16%   /
	/dev/fd0a                 16     368     4%   /SneakerNet
	rhino [~]-414% 	df -t dos
	Filesystem            kbytes    used   avail capacity  Mounted on
	/dev/rfd0b              1424    1320    104    93%    /stuff

The first example shows how to examine the free space on the local 4.3BSD-type file systemsÐthese are the normal UNIX file systems on NEXTSTEP computers.  Note that this includes a locally mounted floppy disk, /dev/fd0a, mounted on /SneakerNet.  

The second example shows the same file systems, but instead of checking the free space available, it examines the number of inodes (files) stored on the file systems. The third example shows a floppy disk with a DOS-format file system. 

Thanks to Alan M. Marcum for this useful tip.

sendmail Security Patch

Two versions of sendmail are provided with NEXTSTEP Release 3.1 and 3.2: sendmail (version 5.67) and sendmail.old (version 5.52). Late last year, the Computer Emergency Response Team (CERT) identified a handful of security problems with NeXT's versions of sendmail. These problems are described in CERT Advisories CA-93: 16 and CA-93: 16A.  In response, NeXT has modified sendmail and sendmail.old to close these security holes. The new versions are now available as a patch on NeXTanswers. To get them, use e-mail or ftp to retrieve documents 1513 and 1514. 

Mending the Error of Our Ways

We'd like to correct a few inaccuracies in the NEXTSTEP In Focus Fall issue.

In ªAdvanced Networking Tools,º we describe several programs that can help you manage a NEXTSTEP network. These programs are part of UNIX. None of the programs was written by NeXT.

Also, in ªUsing SCSI in a PC World,º a diagram depicts a fax modem card on a SCSI chain. However, we're not aware that any such device is really available.