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Troubleshooting

Could not chdir to home directory /root: No such file or directory Error and Solution

When I ssh into my server and login as t root user and I’m getting the following error on screen:

Could not chdir to home directory /root: No such file or directory

How do I fix this error under CentOS or Debian Linux server?
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Sysadmin because even developers need heroes!!!

I‘m trying to run an application and getting the following error on screen:

error while loading shared libraries: libgobject-2.0.so.0

How do I fix this problem under Debian or Ubuntu 64 bit (amd64) Linux?
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Linux Nvidia: NVRM: GPU at 0000:01:00.0 Has Fallen Off The Bus Error and Solution

I‘m using NVIDIA UNIX x86_64 Kernel Module version (driver) 280.13 under Debian 64 bit Linux with Linux kernel 2.6.32-5-amd64 x86_64. However, I’m getting the following errors in my /var/log/messages file

Feb 13 05:53:39 wks01 kernel: [26652.425207] NVRM: GPU at 0000:01:00.0 has fallen off the bus.
Feb 14 03:59:14 wks01 kernel: [39846.244283] NVRM: GPU at 0000:01:00.0 has fallen off the bus.
Feb 17 04:47:32 wks01 kernel: [35237.485871] NVRM: GPU at 0000:01:00.0 has fallen off the bus.
Feb 18 06:53:19 wks01 kernel: [49298.937949] NVRM: GPU at 0000:01:00.0 has fallen off the bus.
Feb 19 06:14:01 wks01 kernel: [28508.567838] NVRM: GPU at 0000:01:00.0 has fallen off the bus.

This error occurs randomly and my laptop goes in hard freez mode. The hard reboot is the only way to recover from complete freeze of my Dell M6500 Debian Linux based laptop. How do I fix this problem?
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Mediawiki PHP Fatal error: Cannot redeclare wfProfileIn() Error and Solution

I‘m running the Mediawiki software under Apache web server running on the Unix operating systems. I’m getting the following in my php error log:

PHP Fatal error: Cannot redeclare wfProfileIn() (previously declared in /var/www/html/wiki/includes/profiler/Profiler.php:14) in /var/www/html/wiki/includes/ProfilerStub.php on line 25.

How do I fix this problem under Mediawiki version 1.18.0?
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Linux: Neighbour Table Overflow Error and Solution

I setup a CentOS Linux based Linux server running as a gateway and firewall server. However, I’m getting the following messages in the /var/log/messages log file:

Dec 20 00:41:01 fw01 kernel: Neighbour table overflow.
Dec 20 00:41:01 fw01 last message repeated 20 times

OR


Dec 20 00:41:01 fw03 kernel: [ 8987.821184] Neighbour table overflow.
Dec 20 00:41:01 fw03 kernel: [ 8987.860465] printk: 100 messages suppressed.

Why does kernel throw “Neighbour table overflow” messages in syslog? How do I fix this problem under Debian / CentOS / RHEL / Fedora / Ubuntu Linux?
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I‘m trying to install the latest version of Lighttpd v1.4.29 web server under RHEL 6.1 AMD64 and getting the following error:

network.c: In function ‘network_init’:
network.c:483: error: ‘EC_KEY’ undeclared (first use in this function)
network.c:483: error: (Each undeclared identifier is reported only once
network.c:483: error: for each function it appears in.)
network.c:483: error: ‘ecdh’ undeclared (first use in this function)
network.c:484: warning: unused variable ‘nid’
make[3]: *** [network.o] Error 1
make[3]: Leaving directory `/opt/new/lighttpd-1.4.29/src’
make[2]: *** [all] Error 2
make[2]: Leaving directory `/opt/new/lighttpd-1.4.29/src’
make[1]: *** [all-recursive] Error 1
make[1]: Leaving directory `/opt/new/lighttpd-1.4.29′
make: *** [all] Error 2

How do I fix this problem under CentOS 5.x, or RHEL, or Red Hat Enterprise Linux 6.x, or Fedora Linux?
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memcached: Failed To Set rlimit For Open Files Error and Solution

I‘m using RHEL 6 / CentOS 6.x and install the memcached server. However, whey I try to start the server using service memcached start command, I get the following error:

Starting memcached: failed to set rlimit for open files. Try running as root or requesting smaller maxconns value. [FAILED]

How do I fix this problem?
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SSH: Agent Admitted Failure To Sign Using The Key Error And Solution

I‘ve recently regenrated and uploaded a new public ssh-key using the ssh-copy-id command. Now I’m getting the following error:

ssh root@server3
Agent admitted failure to sign using the key.
root@server3’s password:

How do I fix this problem?
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Linux: NFS4 mount Error reason given by server: No such file or directory

I recently installed NFS server v4 on my HP Linux server. However, I’m not able to mount it from Linux nfs4 client using the following command:

mount.nfs4 server2:/data /data

I’m getting the following error:

mount.nfs4: mounting server2:/data failed, reason given by server:
No such file or directory

How do I fix this problem?
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Mac OS X: Move the Dock and Menu Bar To External Display

I‘m using an external display with a MacBook Pro. I do not want to use the external monitor as a mirrored display. I need to move the dock and the menu bar to external monitor. How do I setup the external monitor as main display?
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