FAQs by Topic

NFS Mounts
RPM Made Easy
Chicken Cluster
Post install
Broken Hardware
Hardware/Cable/Mouse/Connector Needed

NFS Mounts

RPM Made Easy

  • Q: When I install a package I type rpm -ihv packagename, what do the i h and v stand for.
    A: Use the man tool! i=install h=show hashes to indicate completion v=verbose
  • Q: How can i tell if my machine already has a certain package?
    A: rpm -qa | grep -i packagename
  • Q: What version of package x is on my machine?
    A: Same as above
  • Q: How do I remove a package?
    A: rpm -e installed-package-name
  • Q: I tried installing something and it says it needs other dependent packages, what do I do, where do I get them?
    A: The first place i go is to google and do a search for
    rpm dependency name el4
    From the results your best choice would be a package directly from redhat, this is not often one of your choices. For the most part rpmbone, freshrpms, rpmfind are reliable but you can always check the md5sum for safety.


  • Q: How do i update the software on my machine?
    A: There are a couple of different things you can do.
    1. type 'yum update'
    2. type 'up2date'
    3. run the gui redhat rhn tool
  • Q: Something changed since yesterday on my machine, is an automatic update responsible?
    A: Could be. Check out the /var/log/up2date file and the /var/log/yum.log they will tell you exactly what packages got updated and when.
  • Q: How can i exclude a package from being automatically updated?
    A: Include the line 'exclude software-package' in the /etc/yum.conf
  • Q: I just updated my machine, restarted, and now X won't work.
    A: If one of those updates was to the kernel then this means that you may need to recompile the video driver. See the Monitor/ Display section for more info.
  • Q: Where are the actual rpms that up2date and yum downloads?
    A: In /rpms/el4/up2date and /rpms/el4/yum4
    These locations are defined in the respective config files for up2date and yum.
  • Q: How do I set yum to automatically update every night?
    A: First check to see if it is already turned on by default:
    [root@c3 ~]# /sbin/chkconfig --list | grep yum
    yum 0:off 1:off 2:off 3:off 4:off 5:on 6:off

    This means that it is set to automatically run yum update via chkconfig in runlevel 5 only. Runlevels correspond to the various states you machine can run in. Runlevel 5 is the default for all our machines and indicates that X is runing on the 7th virtual terminal.

    If we had found that it was not on we could turn it on like this:
    [root@c3 ~]# /sbin/chkconfig --level 5 yum on
  • Q: How do I set up2date to automatically update every night?
    A: Same thing as yum except it is called rhn:
    [root@c3 ~]# /sbin/chkconfig --list | grep rhn
    rhnsd 0:off 1:off 2:on 3:on 4:on 5:on 6:off


Display / Monitor

  • Q: I would like to change the display resolution, frequency, what tool do i use?
    A: system-config-display, in general if you are looking for a tool check system-config-* for one that might be relevent.
  • Q: I rebooted after an update and need to rebuild my display drivers.
    A: If this happened to you, you have one of the few nvidia graphics cards. Go into /rpms/el4 and run ./NVIDIA-Linux-x86-1.0-7676-pkg1.run

Distcc Problems

  • Q: I had to kill the distcc process on a machine. What command do i type to get it running again?
    A: Either restart the machine or type: /etc/rc.d/init.d/distccd start
  • Q: I am trying to debug a problem. Where is the distcc log file?
    A: /var/log/distccd.log


  • Q: How do i get the access to the online monitor?
    A: The online tool is located at
    http://nlp.cs.nyu.edu/nagios The username and password are given as needed.
  • Q: Where are the configuration files for nagios?
    A: s1:/s1/admin/nagios
  • Q: How do get Nagios to stop sending me mail for certain conditions? A: There are a couple of files that you may need to change depending on your situation.
    /s1/admin/nagios/etc/contacts.cfg - Individual definitions /s1/admin/nagios/etc/contactgroups.cfg - Group definitions /s1/admin/nagios/etc/services.cfg - Defines which services are being watched and the groups that are notified for each service.


  • Q: How do i figure out if a certain file is on a machine?
    A: The locate tool is perfect for this task and many others don't forget that it is at your disposal.
  • Q: I just installed something and locate can't seem to find the files. Why?
    A: The reason locate can give you the location of files so fast is because they are not being searched in real time. Each night (or some other regular interval) the lookup table is rebuild. If you just installed something it will not be present in the locate table yet.
  • Q: When is the main config file and how do i set locate to update it's database on a nightly basis?
    A: In /etc/updatedb.conf you have the option of setting the parameter DAILY_UPDATE=yes or no.
  • Q: How can i tell locate to rebuild its database right now?
    A: As root type 'updatedb', it will take a long time

The Chicken

  • Q: How do i access it?
    A: Only the head machine of the chicken is accessable from the general internet and then only from machines that have been given access. This machine is named coop.cs.nyu.edu This machine has the only harddisk in the cluster and contains the directories that the diskless machines use.
  • Q: I am on the coop, where can i find the filesystems that are mounted by each of the chickens in the coop.
    A: The root directory for the diskless machines is located on coop in /clusterRoot.
  • Q: Now that i am on the coop, how do i access the individual chicken machines?
    A: Each of the diskless machines is named c1-c32 and can be located at the corresponding ip address


Post install

  • Q: Where is the current post-install script
    A: /rpms/el4/install_el4.sh
  • Q: Will this exact script work next time we have an upgrade?
    A: No. Take a look at it and you will see why. There is virtually no logic in the script; it just installs specific packages, creates links, moves directories and files around. You should use it as a guide for the next round of installs/upgrades.


  • Q: The printer configuration has changed how do i setup my machine to use it?
    A: system-config-printer
  • Q: How do i copy my printer setup to another machine?
    A: On the first machine type: /usr/sbin/printconf-tui --Xexport > printersettings.xml Then on the second machine type: /usr/sbin/printconf-tui --Ximport < printersettings.xml And then restart the cups service on the second machine. /sbin/service cups restart


  • Q: My machine started making a terrible noise, what is wrong?
    A: Well it is usually the fan but could be something else. Open up the machine carefully while it is still running use something flexible (piece of paper) to stop each fan while you listen to the noise diference.
  • Q: I rebooted my machine and it says something about a kernel panic, what do i do?
    A: This could mean there is a serious problem. Run an fsck check on the disk. /sbin/fsck /dev/hda (for the first disk)
  • Q: My mouse is broken.
    A: Replace the batteries
  • Q: My lcd/hard drive/memory/UPS is broken. Who do i call to get it replaced?
    A: In general if the item is a hard drive <3 years old or some other part < 1 year old it is most likely still under warranty. Call the manufacuring company directly and tell them you purchased the part indiividually not from a vendor. If it is under warranty the will help you to get it replaced.

Hardware/Cable/Mouse/Connector/Software Needed

  • Q: Where can i find an extra piece of hardware?
  • Q: How do i get a copy of Windows?


Emergency Instructions

  • restart the machine or restart X or restart the program
  • make sure your.tcsh file isn't he cause of your problem
  • network problems may be solved by /sbin/ifdown eth0; /sbin/ifup eth0