Best of Technical Support

by Various
Multithread Applications

Which library do I need to use for multithread applications? I found pthread.h in /usr/include/, but I didn't find libthread.a in /usr/lib/ as I can in AIX. —Ju Rao Slackware

There is an excellent threads library available called LinuxThreads. You can download the latest version from [For more information on LinuxThreads, see] —Chad Robinson

Missing svgalib

Hi, I am a new user, and I have what I am sure is a simple question. I upgraded the kernel from version 1.2. Now when I run games, I get an error about a missing svgalib. Consequently, I cannot get any picture. I am using an ATI 3D Expression with 2MB. How do I edit the config or lib file in order to indicate which libraries I have? —Jonathan Barrie Slackware

I'll bet you upgraded the libraries as well as the kernel. Nowadays, everything uses shared libraries, and programs can't run unless the right shared libraries are installed.

I'd try ldd <program> to check which libraries it finds and which it doesn't. Once you know which libraries are missing, you can then install the Slackware packages that provide them.

You can also run ldconfig -v to see which libraries are installed; if your program looks for a different version of a library already installed, look for “backward compatibility” packages.

Note that newer distributions trace dependencies between packets, so you are unlikely to experience this error when using them. —Alessandro Rubini

Customizing Login Screens

How do I customize the “Login” screens for TELNET and FTP logins? —Robert Farrell

For TELNET, create and edit the /etc/ file with whatever you wish to be displayed for the login screen. You can also edit the /etc/motd file to display the message of the day after someone logs in.

For FTP, go to the root directory of the FTP space (usually /home/ftp/). You can verify the location and file names by looking in /etc/ftpaccess. Edit the welcome.msg file to whatever you wish to be displayed. If you want specific messages to be displayed when users enter into a particular directory, edit the .message file in that directory. —Mark Bishop

Backup Scheme

In a 50/50-mixed NT/Linux LAN of four to six servers, what is the best tape backup scheme you recommend? Where should I install the backup units—on the NT or Linux or both? What tape backup utilities should I use? What if Solaris 2.5 servers are added? —Jon ChunRed Hat

tar has always been the standard backup tool in the UNIX environment. If you want something more powerful, you should investigate cpio or afio, both of which are standard, command-line tools. BRU and other commercial backup facilities exist as well.

If you want to back up mixed NT and UNIX systems, you will most likely need to use a dedicated backup facility for the NT servers. A backup of NT is nice but backing up your domain server won't be very useful unless you include the registry settings, which only an NT backup tool can do.

The best possible solution is to install a tape drive in each server and use that server's own tools (NTBackup on NT, tar on UNIX) to back it up. That method will provide you with the fastest recovery times as you won't be restoring across the LAN.

If you don't need to cut costs, you can investigate ARCServe or another commercial backup utility. These tools include clients for many platforms, and you can probably get the SCO client working under Linux using iBCS2. That would allow you to use a Windows NT machine to back up your UNIX servers. —Chad Robinson

You can use the SMBFS functionality of the Linux kernel in order to mount remote NT servers on your Linux system:

smbmount //NT_SERVER//FOO /nt_server

Then you can save these directories with tar or any other backup utility.

A more efficient solution (but not free) is to use commercial software such as ARKEIA or BRU which support remote NT/95 system backups. —Pierre Ficheux, Lectra Systèmes

Using a Teles Card

I have a Teles ISDN card, which I would like to use under Linux. After looking around a bit I found a driver in the Red Hat distribution. So, I compiled a new kernel with support for the Teles card. However, I have no idea how to use it. With a standard modem I can talk with at commands to /dev/modem/, but how does it work with the ISDN card? —Rien Broekstra Red Hat

You need the isdn4k-utils. There are other packages, e.g., vbox for building an answering machine, but this is basic. Check or read /usr/src/linux/Documentation/isdn/* for locations of additional packages. —Ralf W. Stephan

I'm fairly certain that you didn't need to recompile your kernel. The Red Hat kernel packages build ISDN support as modules. (I'm sure they do as of 5.0, and I think we did in 4.2 as well.)

Anyway, the best place to find this type of information is in /usr/src/linux/Documentation/isdn/README.HiSax/. Everything you need should be covered there. —Donnie Barnes

Mysterious Temporary Files

I have 160 users in my system. They all use this system strictly as an e-mail server with Netscape as the client. I have noticed that my free disk space has been shrinking over the year. Looking around, I found a whole boatload of files in the /tmp directory which appear to be mail messages with graphic attachments. The file names are pop3a0XXXX and many of them are the same size, have the same owner and have creation dates 2-5 minutes apart. How do I fix this? Does the in.pop3d have a problem? —Mike Gasiorowski Slackware

It looks like your daemon is losing its temporary files; this can happen when users hang up without closing the connection. (Even though the user is causing it to happen, it should still be considered a bug.)

The easiest solution to the problem is to use cron to do a periodic check of /tmp with the following command:

find /tmp -daystart -atime 1 -exec rm \{} \;

--Alessandro Rubini

Mounting a DOS Partition in Linux

Can I mount a DOS logical partition in Linux? I am trying to mount my DOS D: and E: drives. They are both logical partitions within an extended partition of my DOS system. Is this possible in Linux? If so, how do I mount them? Thanks for your help. —Andrew Hamlin Slackware

Yes, this is possible. When Linux boots, you receive a message describing the partitions found on each drive. You can review these messages after Linux boots using the dmesg utility.

Primary partitions are numbered from 1-4, for example, hda3. Extended partitions will be numbered from 5 and up, so the first extended partition on drive hda will be hda5. Add an entry for this drive to your /etc/fstab file, and you will be able to mount it. You can test this manually by typing:

mount /dev/hda5 /mnt -t msdos
Chad Robinson
Installing on a ESDI Drive

How can I install Linux on an ESDI drive? The machine is an IBM portable. The drive is not recognized by the following boot disks: bare, SCSI and idecd. —Chriptopher Ochal

If the hardware is Micro Channel-based, you'll need to get a modified boot disk from the Micro Channel Linux Home Page ( Instructions are located at —Steven Pritchard


I started with Slackware 1.0.2, and top worked fine. I recompiled the kernel for some reason, and top no longer worked. I installed 2.0.0 when it was released and have patched it up to 2.0.31. top still doesn't work. It thinks for a moment then blows out, usually taking the xterm or rxvt with it. I have downloaded all the supporting stuff listed as required for 2.0, and I have installed more memory. free and ps work fine. I do not have a clue where to look for top information. Man pages don't have much. Help! —Bill

Make sure you are running the latest version of procps, available from

Occasionally the layout of proc files changes, which breaks older versions of the ps utilities, including top.

You might also wish to make sure your termcap, curses and ncurses are all up-to-date. —Steven Pritchard

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