Snippets

# Linux : generate high cpu load

  dd if=/dev/urandom | bzip2 -9 >> /dev/null
watch the load value for 4min while running the dd command in background for 60s:

[root@quarz ~]# timeout 240s  perl -e 'while(1) {`uptime` =~ /average: ([\d.]+)/; printf("% 5s %s\n", $1, "#" x ($1 * 10)); sleep 10 }'
 0.00
 0.00
 0.15 #
 0.28 ##
 0.47 ####
 0.55 #####
 0.62 ######
 0.83 ########
 0.78 #######
 0.66 ######
 0.56 #####
 0.47 ####
 0.40 ####
 0.34 ###
 0.28 ##
 0.24 ##
 0.20 ##
 0.17 #
 0.14 #
 0.12 #
 0.10 #
 0.09
 0.07
 0.06
[root@quarz ~]#

# Networking : ping hosts in subnet

  for i in $( seq 1 254 ); do ping -c 1 172.16.1.$i | grep "bytes from" ; done
# Perl : list installed Perl modules
  perl -MCPAN -e 'print CPAN::Shell->r '
perl -MFile::Find=find -MFile::Spec::Functions -Tlw -e 'find { wanted => sub { print canonpath $_ if /\.pm\z/ }, no_chdir => 1 }, @INC'
# Perl : Hello World!
  perl -e "print \"Hello World\!\n\";"  # Win32+Linux
  perl -e "print \"Hello World!\n\";"   # Win32
  perl -e 'print "Hello World!\n;"'     # Linux
# Perl : print O/S name
  perl -e "print $^O"
# Perl : print UNIX time
  perl -e 'print time();'
# Perl : print UTC time in standard format
  use POSIX;
  my $datetime = strftime( '%Y-%m-%dT%H:%M:%SZ', gmtime);  
  print $datetime."\n";
# Perl : generate big file
  perl -e "open(F, '>10MiB.txt'); print F '0' x (1024*1024*10);"
  perl -e "open(F, '>10MB.txt');  print F '0' x (1000*1000*10);"
# Perl : decode base64 encoded file
  perl -MMIME::Base64 -ne 'print decode_base64($_)' <file
# Perl : remove trailing CRLF by removing white spaces and the end of line
  line =~ s/\s+$//g;
# Perl : md5 of string
  perl -MDigest::MD5=md5_hex -e 'print md5_hex("0") . "\n";'

cfcd208495d565ef66e7dff9f98764da

# ESXI : list top 10 utilized volumes

[root@host-esxi:/vmfs/volumes]# df -k | grep VMFS | sort -nrk 5 | head -10 

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motd

todays motd is a quote from rfc865 qotd server djxmmx.net

“Oh the nerves, the nerves; the mysteries of this machine called man! Oh the little that unhinges it, poor creatures that we are!” Charles Dickens (1812-70)


monitoring graphs

traditional mrtg i/f stats graph

interface stats

read here how to create these graphs
cpu

cpu stats

httpd / apache2

apache 1min stats

bind rtt

bind rtt 1day stats


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