History of Computer Problem-Solution (Open) (No. 41)

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  • 1 (2009-04-26 (Sun) 01:23:07)
  • 2 (2009-04-26 (Sun) 01:23:59)
  • 3 (2009-05-08 (Fri) 08:39:27)
  • 4 (2009-05-18 (Mon) 21:55:43)
  • 5 (2009-06-01 (Mon) 21:39:07)
  • 6 (2009-06-02 (Tue) 10:21:13)
  • 7 (2009-06-04 (Thu) 00:16:54)
  • 8 (2009-07-02 (Thu) 12:35:59)
  • 9 (2009-07-02 (Thu) 21:46:59)
  • 10 (2009-07-17 (Fri) 16:01:58)
  • 11 (2009-09-09 (Wed) 13:12:19)
  • 12 (2009-10-10 (Sat) 13:06:29)
  • 13 (2010-01-06 (Wed) 22:37:13)
  • 14 (2010-01-13 (Wed) 23:18:23)
  • 15 (2010-01-17 (Sun) 15:41:21)
  • 16 (2010-01-19 (Tue) 16:12:51)
  • 17 (2010-04-29 (Thu) 15:24:51)
  • 18 (2012-03-29 (Thu) 10:42:18)
  • 19 (2012-08-29 (Wed) 17:46:04)
  • 20 (2012-09-25 (Tue) 17:01:48)
  • 21 (2012-09-26 (Wed) 12:18:33)
  • 22 (2012-10-02 (Tue) 17:01:00)
  • 23 (2013-06-03 (Mon) 17:13:46)
  • 24 (2013-06-05 (Wed) 14:43:13)
  • 25 (2013-08-26 (Mon) 10:20:51)
  • 26 (2013-10-24 (Thu) 09:04:54)
  • 27 (2014-01-17 (Fri) 18:53:28)
  • 28 (2014-07-24 (Thu) 11:35:12)
  • 29 (2014-08-04 (Mon) 10:01:23)
  • 30 (2014-08-05 (Tue) 10:03:57)
  • 31 (2014-08-05 (Tue) 13:01:22)
  • 32 (2014-08-13 (Wed) 10:14:22)
  • 33 (2014-08-14 (Thu) 05:43:40)
  • 34 (2014-08-18 (Mon) 11:43:55)
  • 35 (2014-08-19 (Tue) 12:27:17)
  • 36 (2014-08-22 (Fri) 15:15:39)
  • 37 (2014-08-22 (Fri) 15:53:33)
  • 38 (2014-10-14 (Tue) 17:07:51)
  • 39 (2014-10-17 (Fri) 14:16:07)
  • 40 (2015-08-06 (Thu) 15:02:09)
  • 41 (2016-03-10 (Thu) 11:11:59)

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This is a page of "How to" solve some computer problems that may happen.

P = problem; S = solution

P: (2016.03.10) A new FLEX user cannot receive e-mail.†

S: Don't forget to restart dovecot and postfix after creating the user†

$ sudo service dovecot restart
$ sudo service postfix restart

P: (2015.08.06) Sometimes CPU RAM disc is occupied by unused memory and it isn't deleted or moved automatically. (Particularly in the case we calculated by Quantum espresso in local disc.)†

S: We can free up by following command.†

We can check our current memory usage using this command:

$ watch -n 1 free -m

or

$ watch -n 1 cat /proc/meminfo

We can free up unused memory under Ubuntu/Linux Mint using this command:

$ sudo sysctl -w vm.drop_caches=3

or

$ sudo sync && echo 3 | sudo tee /proc/sys/vm/drop_caches

Please check this site, too:

http://www.upubuntu.com/2013/01/how-to-free-up-unused-memory-in.html

P: (2014.10.17) SSH Error with GSSAPI unsupported options†

When we login to TUBE systems, the following message appears:

/etc/ssh/ssh_config line 53: Unsupported option "gssapiauthentication"
/etc/ssh/ssh_config line 54: Unsupported option "gssapidelegatecredentials"

S: Modify /etc/ssh/ssh_config of FLEX†

Give comment sign to the following lines (or remove them completely)

#    GSSAPIAuthentication yes
#    GSSAPIDelegateCredentials no

Try again to login to TUBE systems.

P: (2014.10.14) HTML helper mode by emacs does not work for updating the timestamp†

S: The hhmts code should be in one line and with a proper spacing in order for emacs to change the HTML time-stamp automatically.†

Therefore,

<!-- hhmts start --> Last modified: Tue Oct 14 16:58:36 JST 2014 <!-- hhmts end  -->

is a CORRECT syntax.

But:

<!-- hhmts start -->
Last modified: Tue Oct 14 16:58:36 JST 2014
<!-- hhmts end -->

is a FALSE syntax.

P: (2014.8.22) DVI file does not show figures after compiling latex files.†

S: Do not use any additional option in graphicx package†

• In the past, people usually add:

  \usepackage[dvipdfmx]{graphicx}

• In the current latex system, excluding any options is sufficient:

  \usepackage{graphicx}

P: (2014.8.20) Thunderbird connection to flex does not work.†

S: Edit /etc/dovecot/conf.d/20-imap.conf†

add

mail_max_userip_connections = 10 

and then

sudo service dovecot restart

P: (2014.8.19) NFS in new FLEX Ubuntu 14.04 is very slow†

S: This is a known bug for the latest ubuntu. We should fix nfs-common and blacklist kerberos configuration.†

• In /etc/default/nfs-common:

  NEED_GSSD=""

  should be modified to be

  NEED_GSSD=yes

• In /etc/modprobe.d/blacklist.conf add the following line

  # Blacklist rpcsec_gss_krb5 kernel module; needed for quick NFSv4 mounts
  blacklist rpcsec_gss_krb5

• Restart nfs daemon:

  $ sudo service nfs-kernel-server restart

Check also this reference: https://bugs.launchpad.net/ubuntu/+source/nfs-utils/+bug/1270445

P: (2014.8.18) Samba sever cannot be accessed in the new FLEX (Ubuntu 14.04)†

S: We found that the location of passdb.tdb should be different to the old FLEX†

• In old FLEX, passdb.tdb is put under

  /var/lib/samba/passdb.tdb

• In new FLEX, passdb.tdb should instead be put under

  /var/lib/samba/private/passdb.tdb

• After putting passdb.tdb in the correct location, don't forget to restart the samba services:

  # sudo service smbd restart
  # sudo service nmbd restart

P: (2014.8.14) E-mail sent through aliasing system (all, slab, etc) always repeats itself around every half an hour†

S: Check the routing policy is correct†

• Check /etc/hosts is set correctly
• Execute again /root/flexroute.sh on old FLEX and /root/tuberoute.sh on new FLEX
• If the problem still exists, restart both old FLEX and new FLEX and execute again above scripts.
• Make sure other computers do not share the same hostname.

P: (2014.8.13) Evince does not work well on Ubuntu 14.02†

S: Do the following way†

sudo ln -s /etc/apparmor.d/usr.bin.evince /etc/apparmor.d/disable 
sudo /etc/init.d/apparmor restart 

and add
export NO_AT_BRIDGE=1
to /etc/environment

P: (2014.8.13) How to change mouse focusing policy.†

S: System --> Preferences --> Window then find a panel "Behaviour" and click: "Select windows when the mouse moves over them"†

P: (2014.8.13) How to change desktop language†

S: - for all users: edit /etc/default/locale and add:†

LANG = "ja_JP.UTF-8" 

I've done this for new FLEX - for a particular user (corresponding user should do by himself): edit ~/.dmrc and add under [Desktop] section:

Language="ja_JP.UTF-8" 

(If we want English, just change above line by

Language="en_US.UTF-8") 

[#t91ab972]

P: How to zip-file in win8.1 with password which is compatible with all users unzip programs:†

S: Download and install 7-zip†

 1. Download the 7-zip installer for your computer from www.7-zip.org.  Run the program and install 7-zip to your computer.
 2. Choosing your files.
 3. Right-click on items and choosing 7-Zip, then Add to archive.
 4. choose your format from Archive format `zip`.
 5. Enter password.
 6. Finally, OK to create the compressed archive.

P: (2014.08.04) FLEX can be accessed from Xlaunch (local), but global component such as website and e-mail seem doesn't work†

S: If you have such a symptom, probably iptable was accidentally modified. We should recover the routing rule to a normal way.†

• Run the following script:

  $ sudo /root/route4flex.sh

P: (2014.07.24) Xming is no longer good for Windows 8.1†

S: Install Vcxsrv, which is a clone of Xming, and remove Xming itself.†

• Download Vcxsrv from the following: http://sourceforge.net/projects/vcxsrv/files/latest/download?source=files
• After installation, do these steps:
  • Open Xlaunch.
  • Choose "One large window" and press Next.
  • Select "Open sesson via xdmcp" and press Next.
  • Connect to host: 172.17.4.135 and press Next.
  • Give the following additional parameters for Vcxsrv:

    -from <your_working_ip_address>

    for example (please change the address, the following is Nugraha's example):

    -from 172.17.4.181

  • Push Next button, Save Configuration, and Finish.

P: (2014.01.17) NIS in tube 60 does not work, although NFS works†

S: Activate ypbind with the following command†

# sysv-rc-conf ypbind on 
# reboot

P: (2013.10.24) X-windows does not work, cannot connect to Flex using X-windows (Xming, NX, etc.)†

S: restart X-windows service in Flex†

#sudo service lightdm restart

P:(2013.08.26) E-mail does not work after shutting down the Flex†

S: restart dovecot and postfix†

#service dovecot start
#service dovecot stop
#service dovecot restart
#sudo /etc/init.d/postfix restart

P:(2013.06.05) how to customize GDM login screen†

S: using ubuntu-tweak†

Install ubuntu-tweak

 #sudo add-apt-repository ppa:tualatrix/ppa
 #sudo apt-get update
 #sudo apt-get install ubuntu-tweak

Launch ubuntu-tweak from terminal and customize the login screen

P: (2013.06.03) xdvi doesn't put period and comma correctly when reading Japanese documents.†

S: Check a tutorial created by other people†

http://d.hatena.ne.jp/tama_sh/20120505/1336197629

Install xdvi-ja

# apt-get install xdvik-ja

Font map file: /etc/texmf/vfontmap.d/

Do the following:

# cd /etc/texmf/vfontmap.d/
# mv 20ptex-jisfonts.map 20ptex-jisfonts.map.org
# mv 20xdvik-ja.map 20xdvik-ja.map.org
# mv 30morisawa.map. 30morisawa.map.org 

Next, check the fc-list the name of the Japanese font to use.

$ fc-list | grep Takao
Takao P??,TakaoPMincho:style=Regular
Takao????,TakaoGothic:style=Regular
Takao P????,TakaoPGothic:style=Regular
TakaoEx????,TakaoExGothic:style=Regular
TakaoEx??,TakaoExMincho:style=Regular
Takao??,TakaoMincho:style=Regular

Add the following lines to a file takao.map (create new if not exist) under the directory /etc/texmf/vfontmap.d/

@TakaoMincho-Regular@
       rml  JIS-H      % ASCII pTeX
       rmlv JIS-V      % ASCII pTeX
       dm   JIS-H      % NTT jTeX
       rml-jis  JIS-H  % ptex-jisfonts

@TakaoGothic-Recular@
       gbm  JIS-H      % ASCII pTeX
       gbmv JIS-V      % ASCII pTeX
       dg   JIS-H      % NTT jTeX
       gbm-jis  JIS-H  % ptex-jisfonts

Finally, update the registration information of the font

# update-vfontmap

P: (2012.10.02) How to remove Ubuntu welcome notes†

Welcome to Ubuntu 11.10 (GNU/Linux 3.0.0-25-generic x86_64)

 * Documentation:  https://help.ubuntu.com/

 New release '12.04 LTS' available.
 Run 'do-release-upgrade' to upgrade to it.

 *** System restart required ***

S: Please check /etc/update-motd.d/ folder†

Then change the permission

 sudo chmod 600 * 

P: (2012.09.26) Warning: File `Makefile' has modification time 38 s in the future†

warning: Clock skew detected. Your build may be incomplete. Such warning appears in TUBE50

S: TUBE50 clock is not synchronized to ntp.tohoku.ac.jp†

• Download ntp
• Configure ntp by folowing this step

P: (2012.09.25)"yes" command appears every time we restart TUBE50†

S: check file /etc/default/nfs-common†

• before:

  NEED_IDMAPD= yes

• after:

  NEED_IDMAPD=yes

  important to note: <space> has meaning to separate the variable in sh script.

P: (2012.08.29) Changing default text editor†

S: run this command:†

sudo update-alternatives --config editor

P: (2012.03.29) Segmentation fault when login tube†

S: run this command /rsaito/bin/no-passwd†

Then press Enter anytime the statement appears

P: (2010.04.29) set-pathname-coding-system function does not exists in new xemacs lisp which existed in flex.†

P: (2010.01.19) Managing ntp†

S: ntp and ntpdate package have to be configured in some tricky ways†

• ntp.conf file

  [root@tube40 ~]# emacs /etc/ntp.conf

  The /etc/ntp.conf file is the main configuration file for Linux NTP in which we place the IP addresses of the servers we want to use. Here we only use one server:

  server  ntp.tohoku.ac.jp    # A stratum 1 server at tohoku.ac.jp
  #server  ntp.redhat.com     # A stratum 2 server at redhat.com

  We have to restart the NTP process every time we make a change to the configuration file for the changes to take effect on the running process.

• To get NTP configured to start at boot, use the line:

  [root@tube40 ~]# chkconfig ntpd on

• To start, stop and restart NTP after booting, follow these examples:

  [root@tube40 ~]# /etc/init.d/ntpd start
  [root@tube40 ~]# /etc/init.d/ntpd stop
  [root@tube40 ~]# /etc/init.d/ntpd restart

• For the synchronization, ntpd should be stopped and ntpdate should be run at least three times, then ntpd can be run again:

  [root@tube40 ~]# /etc/init.d/ntpd stop
  Shutting down ntpd:                                        [  OK  ]
  [root@tube40 ~]# /usr/sbin/ntpdate -u ntp.tohoku.ac.jp
  19 Jan 16:11:08 ntpdate[23079]: adjust time server 130.34.11.117 offset 0.016601 sec
  [root@tube40 ~]# /usr/sbin/ntpdate -u ntp.tohoku.ac.jp
  19 Jan 16:11:09 ntpdate[23080]: adjust time server 130.34.11.117 offset 0.015737 sec
  [root@tube40 ~]# /usr/sbin/ntpdate -u ntp.tohoku.ac.jp
  19 Jan 16:11:13 ntpdate[23081]: adjust time server 130.34.11.117 offset 0.014081 sec
  [root@tube40 ~]# /etc/init.d/ntpd start
  Starting ntpd:                                             [  OK  ]

P: (2010.01.13) The problem of 2010.1.6 is solved but response is slow.†

S: The problem is due to the fact that /etc/mtab is on root (not snapshot)†

Since we do not know what is the process of mount the file. we can not change mtab to snapshot. For a moment, we force mount /home1 and /rsaito on /tmp/home1, /tmp/rsaito

/etc/rc5.d/S28autofs stop
mkdir /tmp/home1
mkdir /tmp/rsaito
mount -n 192.168.2.100:/home1 /tmp/home1
mount -n 192.168.2.100:/rsaito /tmp/rsaito
df

/rsaito/bin/pxe-mount

P: (2010.1.6) /rsaito is not automountd on PXE client.†

S: edit and add flexS:/rsaito information on†

tube30:/nfsboot/root/etc/mtab

P: (2009.10.10) Gnorm logout is slow for Xming etc.†

This is a firewall problem of windows.

S: Open port 16001 tcp†

control panel -> firewall -> add new port ->

Name Esound
Port 16001
     TCP

P: (2009.07.17) Load average of FLEX is very high.†

This is due to mounting problem again (mount NFS). After checking mount status, it is found that a network harddisk was not unmounted nicely before turning off.

S: Re-mount (turn on) the harddisk, and do some safety procedure.†

• check mount status:

  # mount

• umount once (assuming mount point is /mnt/backup):

  # umount -f /mnt/backup

• synchronize several times:

  # sync
  # sync
  # sync

• check df or mount status again
• if the harddisk has been nicely unmounted, then it is safe to turn it off.

P: (2009.07.02) Flex is unstable for logining or e-mails.†

S: mount to tube:/home1-old was not allowed any more.†

comment out one line in /etc/auto.misc 
# home1    172.17.4.134:/home1-old

./S28autofs forcerestart

I also delete in /etc/exports 

the requests from 172.17.4.184 (nuguraha) 172.17.4.188 (mahabubu)
and 172.17.4.127 (furu).

exportfs -a

we also need to restart nfs
/etc/rc5.d/S60nfs restart

P: (2009.06.03) Today we were failed to run ether-wake command on new-PXE server/client machines using new Hub/router.†

S: We manually turn those on and off. After that ether-wake (wake-on-Lan) command was successful.†

P: PXE (network boot) is now installing 2009.5.1†

S: finished. status PXE Server (Open)†

P: We move /etc/passwd then we can not be root. No more even shutdown.†

S: cntl-alt-del and reboot. Then when OS selection, push any arrow.†

Then many selection of OS appears. Select one of OS, and press E. Then select kernel and press E again. Then you can edit the command for starting kernel and add "single" in the last of the command. Finally select "b" for booting and single user mode appears. Make /etc/passwd files and exit and runlevel 5 is recovers.

Even if we used NIS, we should not delete /etc/passwd /etc/group and /etc/shadow.

P: linux emacs ispell error (no language "eu") 2009.4.24†

S: solved. "M-x ispell-change-dictionary" and select english†

S: solved. Edit .emacs to add (setq ispell-dictionary "english")†

P: How to update the files of remote to the files of local†

S: solved. "rsync -avc -e ssh saito@remote:/home/saito/book09/ /rsaito/book09"†