NEXTSTEP In Focus, Winter 1994 (Volume 4, Issue 1).
Copyright ©1994 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 systems--these 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 "Advanced Networking Tools," 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 "Using SCSI in a PC World," a diagram depicts a fax modem card on a SCSI chain. However, we're not aware that any such device is really available.
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