As Senior System Engineer at HCS, Keith wears many hats.  He is responsible for a myriad of duties at HCS.  From project management to taking out the trash, Keith is always willing to do the job at hand and never afraid to get his hands dirty.

Keith has the drive and ability to take a project full circle. He is obsessive when it comes to...

As Senior System Engineer at HCS, Keith wears many hats.  He is responsible for a myriad of duties at HCS.  From project management to taking out the trash, Keith is always willing to do the job at hand and never afraid to get his hands dirty.

Keith has the drive and ability to take a project full circle. He is obsessive when it comes to documentation and communication.  He is a self-starter with the ability to think fast on his feet.

Keith has over 20 years in the IT Industry specializing in Apple Technology.  He’s been a member of the HCS family since 2008.

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Feb
01

How to clear the local DNS cache

macOS Sierra 10.12.0

sudo killall -HUP mDNSResponder

OSX 10.11.0

sudo killall -HUP mDNSResponder

OSX 10.10.4

sudo killall -HUP mDNSResponder

OSX 10.10.0 – 10.10.3

sudo discoveryutil mdnsflushcache

OSX 10.9  – 10.8 – 10.7

sudo killall -HUP mDNSResponder

OSX 10.5 – 10.6

sudo dscacheutil -flushcache


Windows:

ipconfig /flushdns


Linux (depending on what distribution you’re running)

/etc/init.d/named restart

/etc/init.d/nscd restart

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  3494 Hits
3494 Hits
Jan
13

Find files larger than 1GB using command line

This command will find all files on your hard drive that are larger than 1GB and print them to the screen with the file path.

 

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  3333 Hits
3333 Hits
Jan
04

Find all locked files and unlock them

Use this to find all locked files. This example searches the entire HD but you can navigate to a path if necessary.

find / -flags uchg

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  3581 Hits
3581 Hits
Nov
29

Maximum Number of Open Files Error on OS X

I viewed the system log files and saw the following error message every two minutes:

Nov 11 11:27:34 hcstest smbd[416]: in openpam_read_chain(): /etc/pam.d/other: Too many open files
Nov 11 11:27:34 hcstest smbd[416]: in openpam_read_chain(): /etc/pam.conf: Too many open files


I ran the “ulimit -a” command to see what the default open file size and Max user processes size were.  They were 256 and 709 which is very low.

ulimit -a 

core file size          (blocks, -c) 0  
data seg size           (kbytes, -d) unlimited  
file size               (blocks, -f) unlimited  
max locked memory       (kbytes, -l) unlimited  
max memory size         (kbytes, -m) unlimited  
open files                      (-n) 256  
pipe size            (512 bytes, -p) 1  
stack size              (kbytes, -s) 8192  
cpu time               (seconds, -t) unlimited  
max user processes              (-u) 709  
virtual memory          (kbytes, -v) unlimited  

I created two plist files that will change the default open file size and max user processes size limits to 524288 and 2048 and and put them in the following location:

/Library/LaunchDaemons/limit.maxfiles.plist

/Library/LaunchDaemons/limit.maxproc.plist

After a reboot, a re ran the ulimit -a command and the changes were now in effect.  I monitored the system log and these errors are now gone.

Nov 11 11:27:34 hcstest smbd[416]: in openpam_read_chain(): /etc/pam.d/other: Too many open files
Nov 11 11:27:34 hcstest smbd[416]: in openpam_read_chain(): /etc/pam.conf: Too many open files




ulimit -a  

core file size          (blocks, -c) 0  
data seg size           (kbytes, -d) unlimited  
file size               (blocks, -f) unlimited  
max locked memory       (kbytes, -l) unlimited  
max memory size         (kbytes, -m) unlimited  
open files                      (-n) 524288  
pipe size            (512 bytes, -p) 1  
stack size              (kbytes, -s) 8192  
cpu time               (seconds, -t) unlimited  
max user processes              (-u) 2048  
virtual memory          (kbytes, -v) unlimited
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4031 Hits
Oct
13

Troubleshooting Netboot on Cisco Switches

There is a feature on Cisco switches called “DHCP Snooping”.  This feature seems to break Netbooting from OS X servers.  The Netboot image will advertise on your network but you will not be able to boot from it.  To solve the problem you need to Trust DHCP Snooping on the Cisco port that the OS X Netboot server is plugged into.

On a Cisco switch, the commands should be similar to what’s shown below:

Myswitch(config)#interface GigabitEthernet3/47

Myswitch(config-if)#ip dhcp snooping trust

If you’re having this issue and your NOT using Cisco switches, check your switch manual to see if DHCP Snooping is supported and disable it on the switch port that your OS X server is plugged in to.
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3990 Hits
Sep
09

How to change the login window wallpaper from the Command Line in OS X El Capitan

cp /Library/Desktop\ Pictures/Solid\ Colors/Solid\ Aqua\ Blue.png /Library/Caches/com.apple.desktop.admin.png
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  3182 Hits
3182 Hits
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