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comp.unix.aix Frequently Asked Questions (Part 2 of 5)

This posting contains AIX Frequently Asked Questions and their answers. AIX is IBM's version of Unix.
Posted-By: auto-faq 3.3 (Perl 5.005)
Archive-name: aix-faq/part2
Revision: 1.6 2000/10/10 19:59:22
Posting-Frequency: monthly


Subject: 1.200: Some info about tape backups
From: Craig Anderson

The following supplements the information on rmt devices in
InfoExplorer. It is based on my own personal experience with IBM tape
drives running on AIX 3.1. No warranty is expressed or implied.

    BLOCK size (0=variable length)		(ALL)
	Sets the tape block size.  When reading, the block size must be
	set to the block size set when the tape was written.  When
	using some commands, tapes written with ANY block size can be
	read if the block size is set to 0 (variable length) (see
	"BLOCK SIZES" below).

    Use DEVICE BUFFERS during writes		(ALL)
	Set to yes, the device will buffer data internally on writes.
	This greatly improves performance, but under certain cases may
	be undesirable since the data is not written to tape before
	returning a good indication.

    Use EXTENDED file marks			(8mm only)
	Extended file marks take up much more space than short (or
	non-extended) file marks.  But extended file marks can be
	overwritten, allowing data not at the beginning of tape to be
	overwritten (see "FILE MARKS" below).

    RETENSION on tape change or reset		(1/4" only)
	If set to "no" then the tape will not be retentioned
	automatically when the tape is inserted.  Note that this will
	take effect only after the device is used.

     Tape devices support multiple tape files.  Tape files are the
     result of a backup/cpio/tar/dd type command, where the device is
     opened, written to, and closed.  Because tapes allow large
     quantities of data to be written on a single tape, several backups
     (that is, tape files), may be combined on one physical tape.
     Between each tape file is a "tape file mark" or simply "file
     mark".  These file marks are used by the device driver to indicate
     where one tape file ends and another begins.

                              B       E
                   <-------   O       O   ------->
                              T       T
              __ ___________________________ ______________
     physical | \            |       |      \             |physical
     beginning|  \           | tape  |       \            | end
       of     |   \          | file  |        \           |  of
      tape    |    \         | mark  |         \          | tape
     Note that there is a distinction between the beginning of tape
     (BOT) side of a file mark and the end of tape (EOT) side of a file
     mark.  If the head is on the BOT side of a file- mark, "tctl fsf
     1" command will move only to the EOT side of the same file mark.

     With the 1/4" tape drive, writing can only take place
     sequentially, or after blank tape has been detected.  You cannot
     write over data on the tape (except at BOT).  If you wish to add
     data to a tape which has been written and then rewound you should
     space forward file mark until an error occurs.  Only then can
     you start writing again.

     With an 8mm tape drive, writing can only take place before blank
     tape, an EXTENDED file mark, or at BOT.  Thus if several backups
     have been made on one tape and you wish to overwrite one of the
     backups, position the tape to the place you wish to start writing
     and issue the following commands:
	tctl bsf 1
	tctl eof 1
     The first command skips back to the BOT side of the same file
     mark.  The second command rewrites the file mark (writing is
     allowed before extended file marks).  The erase head will erase
     data ahead of the write head, so that after writing the file mark
     the head will be positioned before blank tape.  Only after this
     may you start writing over data in the middle of the tape.  (All
     data beyond where you are currently writing will be lost).  Note
     that you cannot write over short file marks.  In order for this to
     work, the tape must have been written with extended file marks
     (use smit to change this).

     With the 9-track drive writing can take place anywhere on the
     tape although overwriting single blocks of data is not supported.

     On the 8mm drive extended filemarks use 2.2 megabytes of tape and
     can take up to 8.5 seconds to write.  Short filemarks use 184K
     and take up to 1.5 seconds to write.

     When data is written to tape it is written in blocks.  The blocks
     on a tape are separated by inter-record gaps.  It is important to
     understand the structure of the written tape in order to
     understand the problems which can occur with changing block

     In fixed block size mode all blocks on the tape are the same
     size.  They are the size of the block size set in the device
     configuration.  All read()s and write()s to the tape drive must be
     a multiple of the fixed block size.

     In fixed block mode a read() will return as many blocks as needed
     to satisfy the read() request.  If a file mark is encountered
     while reading the tape only the data up until the file mark will
     be returned.

     It is not possible for the tape drive to read a tape whose block
     size is not the same as the block size in the device
     configuration.  (Unless the device configuration is in variable
     size blocks.)

     In variable block size (0) mode, the blocks written on the tape
     are the size of the read() and write() requests to the device
     driver.  In this case, the actual block sizes on the tape can be
     changed using the options to the backup commands (tar -C, cpio -C,
     backup -C).

     In variable mode, read() requests greater than size of the block
     on the tape will return only the data from the next block on the
     tape.  It is this feature that allows tapes written in any block
     size (fixed or variable) to read with the dd command (the output
     from the dd command may be piped to restore, tar, or cpio for
     example.)  Note that backup, tar, and cpio cannot read all tapes
     by using a large block size because they assume there is an error
     if they get a short read().
		dd ibs=128k obs=16k if=/dev/rmt0 | ...

     The tape head is always positioned at an inter-record gap, file
     mark, or blank tape after reading or writing.

     With the 8mm tape drive, using a fixed block size which is not a
     multiple of 1K is inefficient.  The 8mm tape drive always writes
     internally in 1K blocks.  It simulates the effect of variable
     block sizes, but, for example, using a fixed block size of 512
     bytes (or using variable block size and write()ing 512 bytes at a
     time) wastes one half of the tape capacity and gives only one half
     the maximum transfer rate.

     To figure out a tape's actual block size try:

     1). Set the tape to variable block size.
     2). "dd if=<tape> of=/tmp/dummy bs=128k count=1"
     3). "ls -l /tmp/dummy"
     4). The number of bytes in "/tmp/dummy" is the physical block size.

     Many tape drives support both variable and fixed block sizes.

     Variable block mode writes block sizes the size of the write
     command issued (tar and backup specify this with the -b option). 
     In fixed mode, block sizes are fixed and all writes must be a
     multiple of the fixed block size.

     Unix often internally chops larger reads and writes up into
     manageable pieces (often 65535, 65534, or 65532 bytes) before
     doing the actual reads and writes.  This means reads and writes of
     64K bytes are often broken up into a 65535 byte record and a 1
     byte record (In fixed mode the write will fail).  Block sizes >=
     64K (-C128 and greater) should be avoided for this reason.  AIX
     does not break up read and write requests, but be aware of the
     situation on other machines.

     If the tape is written in an unknown block size then set the
     device configuration in smit to use variable size blocks, use the
     "dd" command with a large input block size, and pipe it to the
     restore command.  For example:
	  chdev -l rmt0 -a block_size=0
	  dd if=/dev/rmt0 ibs=128k obs=16k | tar -tvf-


Subject: 1.201: How do I do remote backup?

There seems to be several ways of doing this.  The first approach is a
one-liner to allow tar to reference another machine's device.  The
second is more complete but uses a similar approach.  The latest
addition to this section claims to be able to support mksysb on a
remote machine.  Thanks to all the contibutors.

  tar -b1 -cf - . | rsh REMOTEHOST "dd ibs=512 obs=1024 of=/dev/TAPEDEVICE"

[Ed.: The script has been moved to section 8.06.  I've verified
this script works fine. However, it may be slow for large filesystems
since it creates a temp file of filenames in /tmp.]

There are also several commercial solutions.  One is IBM's SYSBACK/6000
product.  See Question 1.209 for more information.

Open Microsystems sells a product called DistribuTAPE which supports
mksysb to a remote tape drive under AIX 3.2, 4.1 and 4.2.  DistribuTAPE
supports remote tape drives by placing a pseudo tape driver on the
client system, and a server daemon on the server.  More information at


Subject: 1.202: How do I backup a multi-disk volume group?
From: (Daniel Packman)

[ Ed.: I have not verified this procedure. I would actually recommend
  NOT to have one volume group span multiple disks unless you really
  need such big logical volumes. ]

  1. If you have a set of three or more disks in a volume group
     (typically 3 for 5xx machines with three internal drives;
     with only two, the procedures outlined here have to be modified
     to ignore the fact that you don't have a quorum in the volume group)

  2. If one drive has failed (usually only one fails at a time :-) )

It is possible to go through a service boot (the volume group is called
rootvg and one of the 2 good disks on it is called hdisk0):

  importvg -y rootvg hdisk0
  varyonvg -f -n -m1 rootvg

These commands will work, but give error messages. If you wish to mount
a user filesystem, say /u on logical volume /dev/lv00, then

  mount -f /dev/lv00 /v

will work only if jfslog, the journaled file system log device, is not
on the damaged disk. If it is, you must (and can in any case) mount the
filesystem read-only:

  mount -f -r /dev/lv00 /v

This crucial and rather obvious point baffled several level 3 support
personnel at Austin as well as myself for almost a week. Once the file
system(s) of interest are available, they can be saved to tape for
restoration later. Of course, one can expect only about two thirds of a
filesystem to be recoverable if it spans all 3 physical disks. One
other point to remember is that the standard boot procedure from floppy
includes the restore command but does not include the backup command.

* If you do not have other RS6000 machines at your site it is imperative    * 
* that you either build a bootable tape which includes either restore or    * 
* tar or cpio (a bootable floppy set will not have enough space) or at the  *
* very least copy onto a spare floppy backup, cpio, or tar.  The floppy     *
* should be created with backup -ivq so that its contents can be read into  *
* the memory resident system after booting.                                 *

All is not lost if tar, cpio or backup are available on an undamaged
disk that can be mounted. Since tar and cpio are in /bin, they may both
very well be unavailable.

It is a very good idea for those who have tape devices to build a
bootable tape with their desired extra commands in it. Follow the
instructions from IBM but add your desired commands to the following
three files:


If you have anything other than a minimum memory configuration, you
should be able to add many commands.


Subject: 1.203: How do I put multiple backups on a single 8mm tape?
From: (Cary E. Burnette)

There are two possible solutions to this, both of which use /dev/rmt0.1
which is non-rewinding.


To put multiple backups on a single tape, use /dev/rmt0.1, which is a
no-rewind device, using either rdump or backup (both by name & inode
work). Using rdump or backup "byinode" both generate the message that
the tape is rewinding but actually do not. This is an example that
works on my system:

# rsh remote1 -l root /etc/rdump host:/dev/rmt0.1 -Level -u /u
# rsh remote2 -l root /etc/rdump host:/dev/rmt0.1 -Level -u /u
# tctl -f /dev/rmt0.1 rewind       # rewinds the tape

where I am implementing the command from host.
To restore a table of contents of the first I would use 

# restore -f /dev/rmt0.1 -s1 -tv

where the -s1 flag tells restore to go to the first record on the tape. 
Type the exact command again to get the second record. The -s(Number)
means go to Number record from this spot. It works pretty well.

Steve Knodle, Educational Resources Center, Clarkson University

I use:
------------------- --------------------
CONTENTSFILE=`date |dd conv=lcase |sed -e 's/19//' |awk '{print $6 $2 $3}'`
set -x

backup -c -b 56 -$LEVEL -uf /dev/rmt0.1 /
backup -c -b 56 -$LEVEL -uf /dev/rmt0.1 /usr
backup -c -b 56 -$LEVEL -uf /dev/rmt0.1 /u
tctl -f /dev/rmt0 rewind

touch /usr/local/dumps/Contents.$CONTENTSFILE
echo "Dumping /" >>/usr/local/dumps/Contents.$CONTENTSFILE
restore -t -s 1 -f /dev/rmt0.1 >>/usr/local/dumps/Contents.$CONTENTSFILE
echo "Dumping /usr" >>/usr/local/dumps/Contents.$CONTENTSFILE
restore -t -q -s 1 -f /dev/rmt0.1 >>/usr/local/dumps/Contents.$CONTENTSFILE
echo "Dumping /u" >>/usr/local/dumps/Contents.$CONTENTSFILE
restore -t -q -s 1 -f /dev/rmt0.1 >>/usr/local/dumps/Contents.$CONTENTSFILE
tctl -f /dev/rmt0 rewind

I process the table-of-contents first by a little program that does
common prefix encoding, and then compress.

This gives a table of contents file I can keep on-line until the tape
is reused.

Solution #3
   mount | grep jfs | cut -c27- | cut -d" " -f1 | \
     xargs -i backup -${LEVEL} -u -f /dev/rmt1.1 {} > ${DATE}.backup 2>&1


Subject: 1.204: How can I make an exact duplicate of a tape over the network?

The challenge here is not to have to create a temporary file (disk space
limitation) and work across heterogeneous networks.

This script might work:

dd if=$LOCAL ibs=64k obs=512 | rsh remote_host dd ibs=512 obs=64k of=$REMOTE

From: (Daniel Packman)

Daniel provides the following perl script to convert from the known
world's function codes to AIX for compatibility.

# Wrapper to convert input rmt requests to
# AIX 3.2 ioctl numbers.  We pass on all commands we don't understand
# I0 MTWEOF -> I10  STWEOF write and end-of-file record
# I1 MTFSF  -> I11  STFSF  forward space file
# I2 MTBSF  -> I12  STRSF  reverse space file
# I3 MTFSR  -> I13  STFSR  forward space record
# I4 MTBSR  -> I14  STRSR  reverse space record
# I5 MTREW  -> I6   STREW  rewind
# I6 MTOFFL -> I5   STOFFL rewind and unload tape
# I7 MTNOP  -> I0   (no-op? should ignore following count)
# I8 MTRETEN-> I8   STRETEN retension tape, leave at load point
# I9 MTERASE-> I7   STERASE erase tape, leave at load point
#I10 MTEOM (position to end of media ... no ibm equivalent?)
#I11 MTNBSF  (backward space file to BOF ... no ibm equivalent?)
@iocs = (10,11,12,13,14,6,5,0,8,7);
open(RMT,"|/usr/sbin/rmt") || die "Can't open pipe to rmt\n";
$| = 1;
while (<STDIN>) {
  exit 0 if $_ =~ /^[Qq]/;
  print RMT $_ ; }
exit 0;


Subject: 1.205: What is tape block size of 0?
From: (Benson I. Margulies)

Tape devices are generally split into two categories: fixed block and
variable block.  1/4" tape is the fixed block, and 8mm is variable.

On a fixed block size device, the kernel always sends data to the device
in suitable block size lumps, and varying the size passed to write(2)
(e.g., via the bs option to dd) gives the kernel more data to stream. 
On a variable block size device, the kernel writes to the device
whatever passed to it. On an 8mm, it had better be a multiple of 1024
to get efficient tape usage.

AIX has the World's Only Variable Block Size 1/4" tape drive. If you
use SMIT to set the block size to a nonzero value, AIX treats the device
as fixed block size, whether it is or not. By default, 8mm drives are
set to the same size as 1/4", 512 bytes. This is wasteful, but
otherwise mksysb and installp would fail.

If you set the block size to 0, the device is treated as variable block
size, and the size passed to write becomes the physical block size. 
Then if you use a sensible block size to dd, all should be wonderful.


Subject: 1.206: Resetting a hung tape drive
From: (Craig Anderson)

A process accesses the tape drive. The process stops, exits, or whatever,
but still hold on to the drive. When this happens, the process cannot be
killed by any signal and the tape drive cannot be used by any other
process until the machine is rebooted.

The following should help:


AIX, like most UNIX systems has no reset function for tape drives. You
can however send a Bus Device Reset (a standard SCSI message) to the
tape drive using the following piece of code. If the tape drive does
not respond to the BDR, then a SCSI Bus Reset will be sent (and this
will reset every device on the SCSI Bus). SCSI Bus resets are rather
extreme so you should refrain from using this program unnecessarily. 
But there are times (like after you've inserted a jammed/old/bad tape in
an 8mm drive), when there's no other way to reset the device other than
to shutdown and reboot (obviously you can power down and up an external
drive to reset it - and this would be the better choice).

This is actually documented in info, but can be hard to find and
there's no complete program.

/* taperst: resets the tape drive by sending a BDR to the drive. */
#include <stdio.h>
#include <fcntl.h>
#include <errno.h>
#include <sys/scsi.h>

int main(int argc, char **argv)
         /* This can be run only by root */

         if (argc != 2) {
             fprintf(stderr, "Usage: %s /dev/rmt#\n", argv[0]);
             return 1;

         if (openx(argv[1], O_RDONLY, 0, SC_FORCED_OPEN) < 0) {
             return 2;
         return 0;


Subject: 1.207: How do I restore specific files from a mksysb tape?
From: Marc Pawliger (

To recover specific files from a backup made with mksysb, try
$ tctl fsf 3
$ tar xvf /dev/rmt0.1 ./your/file/name

From: Matt Willman (

The procedure changed with AIX 4, which uses backup instead of tar to
write the tape. For AIX 4 the procedure is as follows:

$ tctl fsf 3
$ restore -xvf /dev/rmt0.1 ./your/file/name


Subject: 1.208: How do I read a 5Gbyte tape on a 2Gbyte drive?
Posted by: (Robert Metcalf)

To read a 5Gbyte tape on a 2Gbyte drive, the
tape needs to have been created with a density setting of 20.

The following is from IBM's electronic ASKSUPPORT repository:
   R: The 7208 011 5 GB tape drive has various density settings which are
      as follows:
     | DENSIT| DESCRIPTION              |
     | SETTIN|                          |
     | 140   | Writes in 5.0GB mode and |
     |       | will enable data com-    |
     |       | pression; also, to do    |
     |       | compression you must use |
     |       | "DATA COMPRESSION = yes" |
     | 21    | Writes in 5.0GB mode and |
     |       | will NOT do data com-    |
     |       | pression                 |
     | 20    | Writes in 2.3GB mode and |
     |       | will NOT do data com-    |
     |       | pression                 |
     | 00    | Factory power-on default |
     |       | for 5.0GB data com-      |
     |       | pression mode            |
     The density setting of the 7208 011 must be 20 for it to make a tape
     that is readable by the 7208 001.


Subject: 1.209: What can Sysback do for me?
From: (Tony Johnson)

Sysback provides the flexibility of restoring onto the same system in
the exact same manner, or onto a completely different system with
differnet disk configuration, platform type, kernel, etc, while
reporting any inconsistencies and allowing you to adjust to fit. For
instance, you will get warnings if a particular volume group cannot be
created because the original disks to not exist, or that mirroring
cannot be accomplished because there is no longer enough disk space
because the disks are smaller. You can then select the disks for each
volume group, reduce or add space to filesystems and LVs, exclude
entire VGs or filesystems, etc.  You can even add and delete mirrors,
stripe or un-stripe logical volumes, etc.

In addition, all of the Sysback functions can be performed across the
network, including network boot and network install, and you can
perform striped backups across multipel tape drives, use sequential
tape autoloaders, and perform unattended multi-volume backups with

ON AIX 3.2, mksysb does not retain paging space config, disk LV
placement, mirroring, etc.

On AIX 4.1, it does these on an EXACT same configuration, but does not
allow any flexibility, and still does not retain non-rootvg volume
groups (although you can now use additional commands to backupa nd
restore these).  mksysb also does not allow you to clone onto
different platforms (i.e.  rspc -> rs6k -> rs6ksmp).


Subject: 1.210: How can I get my HP 4mm DAT to work?

For HP25470/80A DDS:
   MRS disabled: Set switches 3,6,7,8=0 and 1,2,4,5=1
   MRS enabled:  Set switches 3,6,7=0 and 1,2,4,5,8=1


Subject: 1.211: How do I copy DAT tapes?

If you have two drives try tcopy(1).  Otherwise the traditional UNIX
approach is ( dd if=/dev/rmt0 bs=1024b | dd of=/dev/rmt1 bs=1024b )
Put that in a while loop using a non-rewinding device to do multiple
files.  To use drives from two different machines either get the GNU
dd (bundled with GNU tar) or use something like.

  $ dd if=/dev/rmt0 bs=1024b | rsh hostname dd of=/dev/rmt0 bs=1024b


Subject: 1.212: How do I speed up backups to DLT tapes?

DLT tapes need high data rates to stay in streaming mode. To achieve
higher data rates, use a variable length block size by setting the fixed
length block size to zero. Also use a buffer size of about 64KB for
backup (128 blocks for tar).


Subject: 1.300: Some info about the memory management system
From: Michael Coggins (MCOG@CHVM1.VNET.IBM.COM).

1. Does AIX use more paging space than other unix systems?

Under many scenarios, AIX requires more paging space than other unix
systems. The AIX VMM implements a technique called "early allocation of
paging space". When a page is allocated in RAM, and it is not a
"client" (NFS) or a "persistent" (disk file) storage page, then it is
considered a "working" storage page. Working storage pages are commonly
an application's stack, data, and any shared memory segments. So, when
a program's stack or data area is increased, and RAM is accessed, the
VMM will allocate space in RAM and space on the paging device. This
means that even before RAM is exhausted, paging space is used. This
does not happen on many other unix systems, although they do keep track
of total VM used.

Example 1: 
Workstation with 64mb RAM is running only one small application that
accesses a few small files. Everything fits into RAM, including all
accessed data. On AIX, some paging space will already be used. On
other unix systems, paging space will be 100% free. Clearly, this is an
example that shows where we use more paging space than the other machines.

Example 2:

Same machine as above, except we are in an environment where many
applications are running with inadequate RAM. Also, the system is
running applications that are started, run, left idle, and not in
constant use. A session of FRAME running in a window, for example. 
What happens is that eventually (theoretically) all applications will be
paged out at least once. On the AIX system and the other systems the
total paging requirements will be the same (assuming similar malloc
algorithm). The major difference is that the AIX system allocated the
paging space pages before they were actually needed, and the other
systems did not allocate them until they were needed. However, most
other systems have an internal variable that gets incremented as virtual
memory pages are used. AIX does not do this. This can cause the AIX
system to run out of paging space (virtual memory), even though malloc()
continues to return memory. This "feature" allows sparse memory
segments to work, but requires that all normal users of malloc()
(sbrk()) know how much virtual memory will be available (actually
impossible), and to handle a paging space low condition. A big problem. 
There are some pretty obvious pros and cons to both methods of doing
Virtual Memory.

2. How much paging space do I need?

Concerning the rule of thumb of having 2 times RAM for paging space:
this is rather simplistic, as are most rules of thumb.  If the machine
is in a "persistent storage environment", meaning that they have a few
small programs, and lots of data, they may not need even as much as 1
times RAM for paging space.  For example, a 1GB database server running
on a 6000 with 256MB of RAM, and only running about 50MB of "working"
storage does not need 512MB of paging space, or even 256MB.  They only
need the amount of paging space that will allow all their working
storage to be paged out to disk.  This is because the 1GB database is
mostly "persistent storage", and will require little or no paging space. 
Excessive paging space may simply mean wasted disk space.  However,
avoid insufficient paging space.  Tip: Don't have more than one paging
space per disk.  Tip: Put lots of RAM in your system - it will use it.

3. Why does vmstat show no free RAM pages?

AIX uses RAM as a possibly huge disk buffer.  If you read a file in the
morning, that file is read into RAM, and left there.  If no other
programs need that RAM, that file will be left in RAM until the machine
is halted.  This means that if you need the file again, access will be
quick.  If you need that RAM, the system will simply use the pages the
file were using. The pages were flushed back to disk earlier.  This
means that you can get a huge speedup in disk access if you have enough
RAM.  For example, a 200MB database will just ease into RAM if you have
a 256MB system.

4. Since vmstat shows no free RAM pages, am I out of RAM?

Probably not. Since disk files will be "mapped" into RAM, if vmstat
shows lots of RAM pages FREE, then you probably have too much RAM (not
usual on a RISC System/6000)!

5. Shouldn't the "avm" and the "fre" fields from vmstat add up to something?

No. The "avm" field tells you how much "Active Virtual Memory" AIX
thinks you are using. This will closely match the amount of paging
space you are using. This number has *ABSOLUTELY* nothing to do with
the amount of RAM you are using, and does *NOT* include your mapped
files (disk files).  The amount of RAM can be determined with
/usr/sbin/bootinfo -r

6. Why does the "fre" field from vmstat sometimes show lots of free
   RAM pages?

This will happen after an application that used a lot of RAM via
"working" storage (not NFS storage, and not disk file or "persistent"
storage) exits. When RAM pages that were used by working storage (a
program's stack and data area) are no longer needed, there is no need to
leave them around. AIX completely frees these RAM pages. The time to
access these pages versus a RAM page holding a "sync'd" mapped file is
almost identical. Therefore, there is no need to periodically "flush" RAM.

7. Is the vmstat "fre" field useful?

The vmstat "fre" field represents the number of free page frames.  If
the number is consistently small (less than 500 pages), this is normal. 
If the number is consistently large (greater than 4000 pages), then you
have more memory than you need in this machine.


Subject: 1.301: How much should I trust the ps memory reports?
From: chukran@austin.VNET.IBM.COM

Using "ps vg" gives a per process tally of memory usage for each running
process.  Several fields give memory usage in different units, but these
numbers do not tell the whole story on where all the memory goes.

First of all, the man page for ps does not give an accurate description
of the memory related fields.  Here is a better description:

RSS - This tells how much RAM resident memory is currently being used
for the text and data segments for a particular process in units of
kilobytes.  (this value will always be a multiple of 4 since memory is
allocated in 4 KB pages).

%MEM - This is the fraction of RSS divided by the total size of RAM for
a particular process.  Since RSS is some subset of the total resident
memory usage for a process, the %MEM value will also be lower than actual.

TRS - This tells how much RAM resident memory is currently being used
for the text segment for a particular process in units of kilobytes. 
This will always be less than or equal to RSS.

SIZE - This tells how much paging space is allocated for this process
for the text and data segments in units of kilobytes.  If the executable
file is on a local filesystem, the page space usage for text is zero. 
If the executable is on an NFS filesystem, the page space usage will be
nonzero.  This number may be greater than RSS, or it may not, depending
on how much of the process is paged in.  The reason RSS can be larger is
that RSS counts text whereas SIZE does not.

TSIZ - This field is absolutely bogus because it is not a multiple of 4
and does not correlate to any of the other fields.

These fields only report on a process text and data segments.  Segment
size which cannot be interrogated at this time are:

       Text portion of shared libraries (segment 13)

       Files that are in use. Open files are cached in memory as
       individual segments.  The traditional kernel cache buffer
       scheme is not used in AIX 3.

       Shared data segments created with shmat.

       Kernel segments such as kernel segment 0, kernel extension
       segments, and virtual memory management segments.

Speaking of kernel segments, the %MEM and RSS report for process zero
are totally bogus for AIX 3.1.  The reason why RSS is so big is that the
kernel segment zero is counted twice.  For AIX 3.2, this has been
changed, but the whole story is still not known.  The RSS value for
process 0 will report a very small number of the swapper private data
segment.  It does not report the size of the kernel segment 0, where the
swapper code lives.

In summary, ps is not a very good tool to measure system memory usage. 
It can give you some idea where some of the memory goes, but it leaves
too many questions unanswered about the total usage.


Subject: 1.302: Which simms do RS6000's use?

This answer is under construction... I'm trying to collect details
about compatable simms.

RS/6000 220,230 USE 2 pair 70ns PS/2 style simms
RS/6000 250,C10 USE 4 pair 70ns PS/2 style simms


Subject: 1.303: What is kproc?

kproc (always PID 514 on AIX 3 and PID 516 on AIX 4) is the kernel's
idle process.


Subject: 1.304: How do I create a RAM disk in AIX?
From: Jeff Wang <>

You can't create a RAM disk in AIX.  The closest related functionality
the operating system gives you is the RAM disk buffer. Read 1.300
sub-section 3.

[Editor's notice: as of 4.3.3 you CAN.  See 1.914 ]


Subject: 1.305: How much RAM (real memory) does my machine have?
From: Michael Abel/resnova

As     root:  bootinfo -r
As any user:  lsattr -E -l sys0 -a realmem

lsdev -C -c memory

shows all memory adapters.  On MCA systems one may add up the values
displayed for each memory card in order to sum up to the amount of
total memory.  On PCI systems only one item (mem0) is
displayed. Additional information may be displayed with

lsattr -E -lmem0

These commands were tested on various IBM systems running AIX relases
3.2.5 and 4.1.4


Subject: 1.306: Why do PIDs run non-sequentially?
From: Julianne F. Haugh <>

The answer (I was there, consider me an authority ...) is that the
PIDs needed to be somewhat unpredictable.  This is because AIX was
originally designed with a number of C2 and B1 features, and one of those
is the notion of covert channel analysis.  Sequential PIDs are a covert
channel (assuming the system has one PID namespace ...) since the value
of the "next" PID is shared by all currently running processes.  So if I
want to sneak some of my classified data out to your co-operating
non-classified program, I can do it by carefully controlling the value
of the "next" PID.


Subject: 1.400: How do I make an informative prompt in the shell?

In the Korn Shell (ksh), the PS1 variable is expanded each time it is
printed, so you can use:

$ export myhost=`hostname`
$ PS1='$LOGNAME@$myhost $PWD \$ '

to get, e.g. 

bengsig@ieibm1 /u/bengsig $

In the C-shell, use:

% set myhost=`hostname`
% alias cd 'chdir \!* > /dev/null; set prompt="$LOGNAME@$myhost $cwd % "'
% cd

to get, e.g.

bengsig@dkunix9 /u/bengsig/aixfaq %

There is no easy solution in the Bourne Shell.  Use the Korn Shell instead.


Subject: 1.401: How do I set up ksh for emacs mode command line editing?

The ksh has an undocumented way of binding the arrowkeys to the emacs
line editing commands. In your .kshrc, add:

alias __A=`echo "\020"`   # up arrow = ^p = back a command
alias __B=`echo "\016"`   # down arrow = ^n = down a command
alias __C=`echo "\006"`   # right arrow = ^f = forward a character
alias __D=`echo "\002"`   # left arrow = ^b = back a character
alias __H=`echo "\001"`   # home = ^a = start of line

Type "set -o emacs" or put this line in your .profile.

Also, you MUST have PTF U406855 for this to work in AIX 3.2.  The APAR #
for the problem is IX25982, which may have been superseded.


Subject: 1.402: Listing files with ls causes a core dump
From: Julianne F. Haugh <>

Scenario: a directory that is shared by N users (N >= 200).
Run 'ls -l' in that directory.  It goes for a while, then
Seg fault(coredump)!

It only occurs when the usernames are displayed (almost every file is
owned by a different person).  The -g and -n options work fine; only -l
and -o (which shows owner and not group) cause it. 

I believe that this problem was corrected by U407548.  If you have that
many users that you are having core dump problems (it took over 200),
you might also want to look into getting the PTF that fixes IX31403. 
That APAR deals with large numbers of accounts and performance problems
associated with looking them up.


Subject: 1.403: How do I put my own text into InfoExplorer?

With AIX 3.1, you cannot do it.  AIX 3.2 has a product called
InfoCrafter that allows you to do that.


Subject: 1.404: InfoExplorer ASCII key bindings 
From: (Charles Hannum)

If you just press 'Return' when it starts up, with 'Basic Screen
Operations' highlighted, you'll get some help.

If you look long enough, you'll find a page named 'Using Keys and Key
Sequences in the InfoExplorer ASCII Interface'.  It describes the key
sequences and actions.  Here are a few to get you started.

Keys       Action

Ctrl-W     Moves between the Navigation screen and the Reading screen.
If the Navigation screen is displayed, you can press Ctrl-W to display
the Reading screen.  If the Reading screen is displayed, you can press
Ctrl-W to display the Navigation screen.

Ctrl-O     Makes the menu bar active or inactive.  If your text cursor is
located in the text area of the screen, you can press Ctrl-O to make the
menu bar active.  If the menu bar is already active, you can press
Ctrl-O to make it inactive, which moves the text cursor to the text area.

Tab     Moves to the next menu bar option in the menu bar.  If a pull-down
menu is not displayed and you press the Right Arrow key, the next menu
bar option is displayed in reverse video.

Subject: 1.405: How can I add new man pages to the system?
From: (Horst Luehrsen)

Put the man pages in /usr/man, e.g. /usr/man/man1/tcsh.1 for the tcsh
man page.  Under AIX 3.1.10, /usr/lib/makewhatis can be used to update
the makewhatis-database /usr/man/whatis so apropos and whatis know about
the added manpages.  /usr/lib/makewhatis should be available on all 3.2

For AIX 4.x, you can store the man pages in the /usr/share/man hierarchy.
/usr/lib/makewhatis is still there.


Subject: 1.406: Why can't I read man pages?  Where is nroff?

Nroff and troff aren't in the base installation.  It is shipped as
part of AIX 3.2.5 but may not be installed.  Use smit to install a
software package called txtfmt.tfs.obj from your 3.2.5 distribution

In AIX 4.x, you need bos.txt.tfs.


Subject: 1.407: Why is my environment only loaded once?

The .profile file is only loaded once (for your login shell) subsequent
shells should be initialized by setting ENV=$HOME/.kshrc (for ksh).

Bash users can use $HOME/.bash_profile for the login shell environment
and $HOME/.bashrc.


Subject: 1.408: Where is the 'nawk' command on my AIX system?
From: Jeff Wang <>

The /bin/nawk that exists on many UNIX flavors is a superset of the
'awk' command, revised by the same original authors to include added
functionality.  All the extra options normally associated with 'nawk'
on other UNIXes have been incorporated into the AIX version of 'awk';
the AIX 'awk' InfoExplorer or man pages include nawk-specific features
such as the "-v" command line option and atan2(), rand(), srand(),
match(), sub(), gsub(), system(), close(), getline functions.

If your AIX version is missing /bin/nawk (as are most AIX 3.x
versions), the simplest way to get around this and maintain script
portability between UNIX platforms is to make a /bin/nawk link to
/bin/awk (as root, of course).  If you do not have root privilege or
do not want to create a /bin/nawk link, to make the script work on
different UNIXes, you may have to test `uname` first and set all
'nawk' references on AIX runs to /bin/awk.  If your script is to only
run on AIX systems, you can just change all references of 'nawk' to
'awk' and everything should still work okay...but check the AIX awk
script on test data prior to making actual runs.

[Editor's note: AIX 4.x already contains a link from /usr/bin/nawk
to /usr/bin/awk.]


1.409: How do I copy InfoExplorer (manpages and more) to my hard drive?
From: David Alexander <>

[Editor's note: While this is documented in one of the AIX manuals
and covered in /usr/lpp/bos/bsdadm (AIX 3 only), it comes up often
enough I thought I would include it here.]

Not all the Info databases are required, so do not copy them all unless the 
customer specifically requests them, or has asked for the software they 
refer to.  These instructions assume you have enough space on /usr.

	Install and mount the InfoExplorer CD-ROM as for use of Info 
	from CD-ROM.

	Log in as Root
	umount /usr/lpp/info/lib/$LANG
	mkdir /mnt/$LANG
	mount -v cdrfs -r /dev/cd0 /mnt/$LANG

	cd /
	cd /mnt/$LANG
	cp -r aix /usr/lpp/info/lib/$LANG
	cp -r aix2 /usr/lpp/info/lib/$LANG
	cp -r compnav /usr/lpp/info/lib/$LANG
	cp -r hardware /usr/lpp/info/lib/$LANG
	cp -r nav /usr/lpp/info/lib/$LANG
	cp -r prog /usr/lpp/info/lib/$LANG
	cp -r uiprog /usr/lpp/info/lib/$LANG

	Other sections can be copied if required:
	Section						Size
	cp -r ada /usr/lpp/info/lib/$LANG		7.2  Mb
	cp -r assemb /usr/lpp/info/lib/$LANG		5.23 Mb
	cp -r cxx /usr/lpp/info/lib/$LANG		6.52 Mb
	cp -r dce /usr/lpp/info/lib/$LANG		3.8  Mb
	cp -r encina /usr/lpp/info/lib/$LANG		2.67 Mb
	cp -r fortran /usr/lpp/info/lib/$LANG		6.85 Mb
	cp -r graph /usr/lpp/info/lib/$LANG		9.75 Mb
	cp -r graph2 /usr/lpp/info/lib/$LANG		4.1  Mb
	cp -r pascal /usr/lpp/info/lib/$LANG		3.23 Mb

	umount /mnt/$LANG
	eject the CD-ROM


Subject: 1.410: Why can't I set my default shell to one we've just installed?

When adding new shells to the system, add them to the "shells=" line
in /etc/security/login.cfg so they can be used during ftp and rlogin
by users who use them as their default shell.

Subject: 1.411: Why do I get the "Unable to connect socket: 3"
                starting Info-Explorer?

It's a bug in the way infod sets the initial permission on the            
/tmp/.info-help socket. Do a chmod 777 on /tmp/.info-help and the
message will go away. (Charlie McGuire,

This problem was fixed by APAR IX43230, PTF U432315
(Paul Sitz,


Subject: 1.412: Why can't I write a setuid shell script?
From: (Michael Wojcik)

AIX, as of about the first release of 3.2.5* does not allow SUID scripts.
(It ignores the SUID and SGID bits on scripts.)  They're a huge security

If you really want to run a script SUID, you can create a small C program
that does a setuid(0) and then system()'s your script.  (Actually, the
setuid() call isn't necessary on all Unixes; IIRC, it's not on AIX 3.2.5,
but YYMV.)  Make the program SUID.  Be very careful.

There are other similar solutions.  You might also want to look into
sudo, which handles this sort of thing in a somewhat more controlled

* Julianne Frances Haugh ( writes:

I raised an objection to set-ID shell scripts before AIX 3.1 was
golden.  ... it was finally done in the 3009 PTF for AIX 3.1.


Subject: 1.500  Which release of X11 do I have?

AIX 4.x includes X11 R5 and Motif 1.2.

On AIX 3, Run 'lslpp -h X11rte.obj'.
If your output has a line similar to:

            01.02.0000.0000 COMPLETE   COMMIT     03/04/93   02:05:11 root

you have X11 R4. If your output has a line similar to:

    U491068 01.02.0003.0000 COMPLETE   COMMIT     07/28/93   12:50:42 root

you have X11 R5. Some people also call these AIXwindows 1.2.0 and
1.2.3.  'lslpp -h X11rte.motif1.2.obj' should tell you if you are
running Motif 1.2.

From: Jan Just Keijser <> 

AIX 4.1 and AIX 4.2 come with X11R5 and Motif 1.2.4

AIX 4.3.1 (and perhaps 4.3.0) comes with X11R6.1 and Motif 2.1

Some executables which run fine using the X11R5 libraries may not run
when using the X11R6.1 libraries; you can specify which X11 libraries to
use by setting
for X11R5 and
for X11R6.1; by default,
    /usr/lib/libX11.a -> /usr/lpp/X11/lib/R6/libX11.a
and also for the other libraries on AIX 4.3.1.

On most of the AIX 4.1.x and 4.2.1 boxes I have seen the default is
  /usr/lib/libX11.a -> /usr/lpp/X11/lib/R4/libX11.a
ie the default libraries are the X11R4 libraries and _NOT_ the R5
libraries; this may also be due to the setup at my site.


Subject: 1.501: How to prevent ctrl-alt-backspace from killing the X session

Start X with 'xinit -T' to disable ctrl-alt-backspace from stopping X.


Subject: 1.502: Who has a termcap/terminfo source for the HFT console?

The console used on the RISC System/6000, PS/2 and RT can be used as a
terminal on another system with the termcap below.  You can find this
and other termcaps in /lib/libtermcap/termcap.src, including IBM
specific ones.  The terminfo sources are stored in /usr/lib/terminfo/*.ti.
This termcap can also be used from an aixterm window.



1.503: How can I look at PostScript files?  Why is "dpsexec" so lousy?
From: Marc Pawliger <>

showps comes with the 1.2.3 (X11R5) version of the X11rte.ext.obj LPP.
Very nice PS file previewer from Adobe.  Replaces xpsview which came
with pre-1.2.3 Installed as /usr/lpp/DPS/showps/showps

From: VRBASS@ATLVMIC1 (Vance R. Bass)

You can look at PostScript files using either "xpreview" (in the
optionally installable text formatting services) or you can get
Ghostscript and Ghostview from a comp.sources.x server and build it

>From the "xpreview" man page:
The xpreview command is an AIXwindows 1.2- and Motif 1.1-based
application that displays output from the troff command on an AIXwindows
display.  The troff command output file must be prepared for any one of
the devX100, devX100K or devpsc devices.  The xpreview command also
displays PostScript language files that begin with %!.

"dpsexec" is NOT intended to be a full-service document browser, but
rather a simple DPS code debugger.  If you insist on using it, you can
edit your PS code to remove the "showpage" (which will reset dpsexec
and clear the window) to view single-page files.  It does not handle
multi-page files gracefully.


Subject: 1.504: unix:0 vs `hostname`:0

1.) Is there any way to get the machine to check its local host table
    first without renaming resolv.conf?

[AIX 3.2 only]
PTF U412845 implements an environment variable to set the resolver
time out in AIX 3.2.  This allows you to set RES_TIMEOUT to the number
of seconds before it times out, a failing a DNS query the machine will
consult /etc/hosts.  

2.) How do you tell X applications where you are if the console display 
    is unix:0?

From: David L. Crow <>

  I would suggest that if you have R5, use ":<display>.<screen>".  I do
  not believe that R4 clients will understand :0, so I would suggest
  unix:0 for them.

  Without specifying unix or the hostname, you will get the fastest
  transport mechanism.  While currently there are only two transport
  methods in the AIXwindows X server (Unix sockets and TCP sockets),
  many vendors are looking at using shared memory as a transport method. 
  If you use :0 (or :0.0 or :1, etc.), then you should get the best
  performance regardless of the available transport methods.

From: Marc Pawliger <>

  Using "unix:0" or "hostname:0" when the X11 Shared Memory Transport
(SMT) is installed as part of the 1.2.3 X11rte.obj (X11R5) will incur
a penalty vs. using ":0" See /usr/lpp/X11/README.SMT

3.) Is there a significant performance penalty incurred by using
    `hostname`:0 as DISPLAY?

  Yes! Using unix:0, you are using Unix sockets.  These are much faster
  than their TCP socket counterparts.


Subject: 1.505: VT100 key bindings for aixterm
From: <Konrad Haedener>

Add this to your .Xdefaults file and start your VAX session with
'aixterm -v -name vt100 -e telnet MYVAXHOST'

vt100.vt102: true
vt100.fullcursor: false
vt100.translations:    <Key>F1: string(0x1b) string("OP") \n\
                       <Key>F2: string(0x1b) string("OQ") \n\
                       <Key>F3: string(0x1b) string("OR") \n\
                       <Key>F4: string(0x1b) string("OS") \n\
                       <Key>KP_0: string(0x1b) string("Op") \n\
                       <Key>KP_1: string(0x1b) string("Oq") \n\
                       <Key>KP_2: string(0x1b) string("Or") \n\
                       <Key>KP_3: string(0x1b) string("Os") \n\
                       <Key>KP_4: string(0x1b) string("Ot") \n\
                       <Key>KP_5: string(0x1b) string("Ou") \n\
                       <Key>KP_6: string(0x1b) string("Ov") \n\
                       <Key>KP_7: string(0x1b) string("Ow") \n\
                       <Key>KP_8: string(0x1b) string("Ox") \n\
                       <Key>KP_9: string(0x1b) string("Oy") \n\
                       <Key>KP_Divide: string(0x1b) string("OQ") \n\
                       <Key>KP_Multiply: string(0x1b) string("OR") \n\
                       <Key>KP_Subtract: string(0x1b) string("OS") \n\
                       <Key>KP_Add: string(0x1b) string("Om") \n\
                       <Key>KP_Enter: string(0x1b) string("OM") \n\
                       <Key>KP_Decimal: string(0x1b) string("On") \n\
                       <Key>Next: string(0x1b) string("Ol") \n\
                       <Key>Left: string(0x1b) string("OD") \n\
                       <Key>Up: string(0x1b) string("OA") \n\
                       <Key>Right: string(0x1b) string("OC") \n\
                       <Key>BackSpace : string(0x7f) \n\
                       <Key>Down: string(0x1b) string("OB")

You should also add


to your .profile.


Subject: 1.506: Is there a screen saver that does not use excessive CPU?
From: Don Buchholz <>

Try using xlock with these options:

	xlock -mode life -count 1500 -nice 20 -root

From: (Pranav Vakil)

Use mlock -hide to hide the background. You can also modify the mlock
(/usr/local/tools/mlock) code to allow the standard X screen saver to
take effect. The timeout value is originally set to 0 which means the
screen saver is off. Modify this to be 120 (2 minutes) and set the
interval time to be 60 (1 minute). Using these intervals, I have found
that over a 24 hour period, it uses only .3 cpu minutes.


Subject: 1.507: Where are the colors, available for an X session, listed.

/usr/lpp/x_st_mgr/bin/rgb.txt and on AIX 4.2, the file is


Subject: 1.508: Why does my app hang the X server but not an X station?
From: Bjorn P. Brox <>

/usr/lpp/X11/README.SMT X client/server communication uses a 64k
buffer by default.  The size of this buffer is controled by the
X_SHM_SIZE environment variable increasing the size of the buffer has
been used to prevent some applications from hanging the X server :)


Subject: 1.509: How do I switch the control and caps lock key bindings?

If you are running the X window system, you can put the following into

  remove Lock = Caps_Lock
  remove Control = Control_L
  keysym Control_L = Caps_Lock
  keysym Caps_Lock = Control_L
  add Lock = Caps_Lock
  add Control = Control_L

Hidden Hint: Use (xmodmap -e "pointer = 3 2 1") to make the mouse
lefty friendly.


Subject: 1.510: Missing fonts?

If your Xserver supports X11R5 try running a font server (edit
/usr/lib/X11/fs/config and run fsconf && startsrc -s fs) Consult your
Xserver instructions on how to include a font server in your font


Subject: 1.511: What's the termcap entry for an IBM 3151 look like?

# Written by Aleksandar Milivojevic,
# 24.09.1994
I2|ibm3151|3151|IBM 3151 terminal:\


Subject: 1.512: Errors starting X11 application binaries from aixpdslib.
From: <URL:>

We have been aware of the problem people have with dynamic links
when running the prebuilt of X-stuffs from this library.

The typical error messages will be:

    Could not load program [program_name]
    Member shr4.o not found or file not an archive
    Member shr4.o not found or file not an archive
    Could not load library libXt.a[shr4.o]
    Error was: No such file or directory

It's because that we built the programs using X11 libraries of MIT
which are not compatible with those of IBM.  If this is the case,
then please get the compressed tarred file of the source code instead,
and recompile them on your system using your libraries.

Subject: 1.513: .XShm*, .sm* (Shared memory) Link errors building 
                 Xwindows applications.

Link errors that refer to .XShm* often times are a result of compiling
applications to take advantage of the Shared Memory extension of the X
server.  You may either compile without shared memory or load the
shared memory extensions. (see /usr/lpp/X11/README and README.SMT) A
script for rebuilding your X server with the shared memory can be found
in /usr/lpp/X11/Xamples/server.


Subject: 1.514: How do I set my DISPLAY when I login to another machine?

Though this is not a question specific to AIX, it appears often enough
to warrant an answer here.  There are lots of approaches, some of which
are described in the X Windows FAQ.  Most involve a little login shell
programing to parse the output of `who` or `who am i`.
<URL:> by will help if you are willing/able to install it
suid.  See the X Windows FAQ and newsgroup for more information.

Hostwhence is also availabile in the "lsof" smit-installable package on The installation scripts use ACLs to allow hostwhence to
read /dev/kmem without being set-uid-root.


Subject: 1.515:  Why doesn't Netscape work?
From: "Gary R. Hook" <>

The problem is that Netscape has statically linked libc into 
Mozilla.  When the AIX 3 libc code (setlocale()) tries to
load an AIX 4 locale, the two are incompatible and a core
dump ensues.  AIX 4 locales have to be loaded by AIX 4 libc.
Using LANG=C causes a lot of locale code to be bypassed, allowing
the application to avoid loading a non-C locale, and to continue

>From: Colin <>
Here is a shell script that works around Netscape's problems by
setting the LANG and CLASSPATH environment variables.

if [ $# -eq 0 ]; then
   /path/to/netscape &
   /path/to/netscape $* &


Subject: 1.600: My named dies frequently, why?
From: (John P. Eisenmenger)

Running on 3.2, named dies frequently on network's primary name server.

Try the following:

     stopsrc -s named		# stop running named
     setenv MALLOCTYPE 3.1	# use 3.1 memory allocation algorithm
     /etc/named ...		# don't use smit to start named

You might be able to use startsrc/smit after setting MALLOCTYPE and get
the same effect, but I'm not sure.

[According to John, the problem is malloc() in the named code. He
 also suggests using Berkeley's bind, which he has ported and can be
 ftp'ed from -ed]

Two ptfs should fix this problem. Get U412332 and U414752.

Christophe Wolfhugel <> reports
that bind 4.9 works fine on AIX 3.2 and without MALLOCTYPE=3.1.


Subject: 1.601: How do I trace ethernet packets on an AIX system?
From: (Andreas Siegert)

Do the following:

     iptrace -i en0 /tmp/ipt

The iptrace backgrounds.  Find its process id and kill it when you are
ready.  Then run

     ipreport -rns /tmp/ipt >/tmp/ipr

and look at the output.  The current version of Info does not document
the r, n and s options but they are quite useful for layering the output.


Subject: 1.602 What is the authorized way of starting automount at boot time?
From: (Curt Finch)

I put this in my /etc/inittab:

automount:2:once:/usr/etc/automount -T -T -T -v >/tmp/ 2>&1

I hereby dub it authorized.

Jim Salter <> writes: You can also use the command:
'mkitab "automount:2:once:/usr/etc/..."' to avoid editing the file by hand.


Subject: 1.603: How do I set a tty port for both dial-in and dial-out?

Set the mode of the tty to be either 'shared' or 'delayed'. 


Subject: 1.604: How to move or copy whole directory trees across a network

The following command will move an entire directory tree across a network 
while preserving permissions, uids and gids.

      $rsh RemoteHost "cd TargetDir; tar -cBf - ." | tar -xvBf -


The tar-create is rsh'd to the remote system and is written to
stdout (the pipe).

The local system is extracting the tar that is being read from
stdin (the pipe).

From: abeloni <>

Another method is:

	rcp -rp host1:/dir host2:/dir


Subject: 1.605: How can I send mail to hosts that cannot be pinged?
From:!dedourek (John DeDourek)

AIX 3.2 as shipped is configured to only send mail to mail addresses
which include a host name.  Many organizations use a mail address whose
"host name" part is not a host name (technically an MX name).  To change
the configuration of the AIX mailer, login as root.  Then edit the file
/etc/ to remove the comment marker ("# ") at the beginning of
the line which reads:
    # OK MX

Now rebuild the machine readable form of the configuration with
    sendmail -bz

and finally restart signal sendmail to load the new configuration by one
of the following:
     stopsrc -s sendmail
     startsrc -s sendmail
     kill -1 `cat /etc/`

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