Linux Workstations
- Are there dedicated, Linux-only hosts that I can log into remotely to run my programs/compute jobs?
- How can I find out which workstations are not being used?
- Every time I try to log into a Linux workstation, I immediately get logged out. What is wrong?
- What is rmproc and when can I use it? How do I remove remote processes running on my workstation?
- How do I mount a CD disk on a Linux machine?
- How do I give people access to my CAEN-supported Linux workstation?
- I've been having difficulty looking at remote processes on my CAEN-supported Linux workstation with the rsh command. What can I do?
- How do I export the local file system of my CAEN-supported machine to be accessible from other machines?
- I tried starting Mozilla Firefox and I received a message that it was already running, or that some process ID was using my session, and it is locked. How do I fix this?
- Does CAEN have a font server I can use with my X applications?
- How do I use the IMSL math library?
Are there dedicated, Linux-only hosts that I can log into remotely to run my programs/compute jobs?
Yes, and No.
CAEN does not allow remote login access to Linux lab computers from outside the U-M network, but in order to provide some means for the College of Engineering community to access Linux computers from home, CAEN set up the login servers (login.engin.umich.edu). These login servers are for interactive use only, and users should refrain from running large or re-spawning background and/or CPU-intensive jobs on these servers. For more information, please see:
How can I find out which workstations are not being used?
You can find available CAEN Linux workstations with the following command.
hostinfo -linux -allHostinfo will report the hostname, load, whether someone is at the console, and free space in /tmp for all CAEN lab computers currently running Linux.
Type hostinfo -help at the prompt for more information.
Every time I try to log into a Linux workstation, I immediately get logged out. What is wrong?
Please see:
What is rmproc and when can I use it? How do I remove remote processes running on my workstation?
The remove process (rmproc) program allows the console user of a Linux lab workstation to selectively kill remote user processes. To interactively use rmproc, type rmproc. You will then be prompted whether to kill or ignore each eligible process on the machine. To just list processes eligible for killing, type rmproc -l.
Depending on the characteristics of a given process, rmproc will provide advice as to whether or not it is worth killing. Rmproc excludes system processes from consideration and will not list them or provide the option of killing them. Small jobs, defined for example to be those that have used less than 10 minutes of CPU time or those that are suspended, also will be excluded.
Private machine owners who are interested in running rmproc on their machines should Contact CAEN to request this service. Requests must come from the machine owner or technical contact.
How do I mount a CD disk on a Linux machine?
In general, anytime you insert a disk into a Linux machine's drive in a CAEN lab, it should just mount automatically. Generally, if the machine has a specific drive, it will automatically be set up under the mount point:
/mnt/cdrom/
If you are trying to read a CD, when you log into the machine's console, the system assigns ownership of the CD device to your user ID (UID). You should then be able to mount it normally with the following command:
mount /mnt/cdrom/
How do I give people access to my CAEN-supported Linux workstation?
To give someone access to your workstation, simply submit an authenticated request via Contact CAEN, listing the U-M uniqnames of the people you wish to include in the password file.
You may request access be granted to your workstation if the person is not eligible for a CAEN computing account, or even if they do not have a U-M uniqname. This is especially useful to allow someone to use the CAEN software on your research machine after their regular CAEN computing account has expired, or if you are conducting research with someone who is outside the University. You can also request that local directory space be allocated for these accounts. Note: Private machine account holders will only have login access to your machines, and will not be eligible for other CAEN computing services such as online storage space.
The request must be submitted by the person listed in the CAEN database as the official contact person for the workstation.
I've been having difficulty looking at remote processes on my CAEN-supported Linux workstation with the rsh command. What can I do?
In general, private hosts are not trusted for remote (r*) commands. The host you are on is probably not listed in the /etc/hosts.equiv file of the host to which you are trying to rsh. If desired, a registered contact for your host can Contact CAEN and request that list of machine names be placed into the /etc/hosts.equiv file for your workstation.
Note: CAEN does not recommend using rsh because its not encrypted and it allows those monitoring network traffic to easily hack or sniff your password and other information. CAEN suggests using SSH whenever possible.
How do I export the local file system of my CAEN-supported machine to be accessible from other machines?
Owners of CAEN-supported machines can choose to have a local, non-AFS disk drive to use NFS (Network File System) for file sharing. If you would like a directory on your machine to be accessible by a remote machine, you will need to have it exported. Requests can only be made by the owner or administrator of the machine. Requests can be sent via the Contact CAEN feature of this website. Requests must include the following information:
- Name of machine to export from
- Directory to be exported
- Names of machines that should have access to the exported directory
NOTE: For safety, CAEN recommends exporting files to only a certain list of machines (e.g. a group of Linux machines with restricted access). Due to the method in which NFS works, there is no way to prevent people from obtaining unauthorized access to your files if they are able to log into a machine to which the files are exported. Exporting files to all CAEN machines& runs the risk of files being read or written by anyone with access to CAEN labs.
I tried starting Mozilla Firefox and I received a message that it was already running, or that some process ID was using my session, and it is locked. How do I fix this?
Many times when you start a software program, the program will create a "lock" file for the session in your profile and/or home directory. If the program then quits improperly, or if you log out of the computer without first exiting the program, this lock file can remain and prevent the program from running until it is removed. So if you receive this type of error message when attempting to open Firefox, it is most likely referring to a previous (locked) process or session.
You can type the following commands to remove the lock file from your ~/.mozilla configuration folder, but you may need to examine the folder to determine the exact location of the lock file:
rm -f ~/.mozilla/firefox/*.default/lock
rm -f ~/.mozilla/firefox/*.default/.parentlock
Note: In Windows, you will want to remove the lock file from your Firefox profile, which can be accessed in your NAS space via the N: network drive. This can typically be found at:
N:\profiles\lab####\profile.V2\appdata\Mozilla\Firefox\Profiles\*.default\parent.lock
where #### is the academic year. Once the lock file is removed, you should then be able to start the Firefox browser. If you were using a program other than Firefox, check that program's configuration directory for a lock file.
Does CAEN have a font server I can use with my X applications?
Yes. CAEN's font server is fontsrvr.engin.umich.edu. It must be connected to via TCP port 7100, i.e.:
fontsrvr.engin.umich.edu:7100
For example, you can use the following command to set it up:
xset fp+ tcp/fontsrvr.engin.umich.edu:7100
How do I use the IMSL math library?
The IMSL libraries are a collection of Fortran and C routines and functions useful in research and mathematical analysis. On CAEN Linux machines the libraries are only available in binary form (i.e. no source code is available). To use IMSL you must first set up your environment. The easiest way to do this is to type:
imsl
Once your Linux shell is setup, an example program that calls the C/Math or C/Stat library can be compiled and linked with the command similar to:
$CC -o prog $CFLAGS prog.c $LINK_CNL
For a FORTRAN program, the compile statement will be similar to:
$FC -o prog $FFLAGS prog.f $LINK_FNL
One of the benefits of IMSL is that the user can maximize performance by linking against the vendor supplied BLAS libraries, e.g.:
$FC -o prog $FFLAGS prog.f $LINK_FNL_PERF
Much more documentation is available online. To access CAEN's documentation type the following command at the Linux prompt:
imsl_doc
Also be sure to check the manufacturer's website: http://www.vni.com/products/imsl/
