X11 forwarding for other users

1. in Your session do xauth list and find your correct auth (the one matching $DISPLAY), and copy the whole line

2. do your sudo or su and then do xauth add <the line copied in step one>


Big Thanks to http://blog.cyphermox.net/2008/05/ssh-x11-forwarding-for-other-users.html

add remove dynamic bind dns records

IF ZONES EXIST

nsupdate -k $keyfile
> server 127.0.0.1
> update add server1.example.com 3600 A 10.0.0.1
> send
> update add 1.0.0.10.in-addr.arpa 3600 in ptr server1.example.com.
> send

clear and reinitialize kerberos cache

kdestroy -A && kinit

remove a line from a file

sed -i '22d' /root/.ssh/known_hosts


or better is to do ssh-keygen  -R hostname/IP

linux change root disk grub-install

redetect disks by grub-install in case dd ing 446 bytes from one disk to the other did not work, /boot/grub/devices.map needs to be fixed

perl command line arguments

#!/usr/bin/perl -w

use strict;
use Getopt::Long;
use utils qw( &usage );
my($host,$port,$user,$password,$file,$opt_w,$opt_c) = ("",22,"","","","","","","","");

Getopt::Long::Configure('bundling', 'no_ignore_case');
GetOptions
("H|host=s"     => \$host,
 "p|port=s"     => \$port,
 "U|user=s"     => \$user,
 "P|password=s" => \$password,
 "F|file=s"     => \$file,
 "w|warning=s"  => \$opt_w,
 "c|critical=s" => \$opt_c,
 );


($host) ||  usage("Host not specified\n");
($user) ||  usage("SFTP Username not specified\n");
($password) || usage("SFTP password not specified\n");
($file) ||  usage("File to upload and download not specified\n");
($opt_w) || usage("Warning threshold not specified\n");
($opt_c) || usage("Critical threshold not specified\n");

rvm install ruby specific version

\curl -k -sSL https://get.rvm.io | bash -s stable --ruby=1.9.3-p362

replace root with lvm

In rescue mode::

KER=`ls /lib/modules` #if single kernel
initrd -v -f /boot/initrd-$KER.img $KER

DAAA  :::: make sure you do not have rd_NO_LVM in the options passed to vmlinuz

linux remove sata disk

echo 1 > /sys/block/(whatever)/device/delete

thanks to http://unix.stackexchange.com/questions/43413/how-can-i-safely-remove-a-sata-disk-from-a-running-system

centos enable LVM for root disk

1. do vgchange -a y /dev/vg1/lv_root

this enables you to see the logical volume from the rescue/gparted disk

1. do mkinitrd -f /boot/initrd-2.6.xxxxxx 2.6.xxxxxxx

extend an lvm with a file on another partition

if resizing another lvm and file system is not an option (time consuming) a temp solution will be

dd if=/dev/zero of=/var/disk1_2.dsk bs=1M count=100

losetup /dev/loop0 /var/disk1_2.dsk

pvcreate /dev/loop0

vgextend /dev/VG1/lv_disk1

lvextend -L+100M /dev/VG1/lv_disk1

vim /etc/rc.local
losetup /dev/loop0 /var/disk1_2.dsk 

awk gsub for regular expression modification of strings

Use gsub like this

ping -c1 10.10.27.5 > /dev/null;arp 10.10.27.5 | awk '/ether/ {gsub(/:/,"",$3);print $3}'

awk print last line

awk 'END{print}'

remove unkown device from VG

add a new disk and assign the missing uuid to it

pvcreate --uuid 56ogEk-OzLS-cKBc-z9vJ-kP65-DUBI-hwZPSu /dev/sdc1

then remove it from the VG and PVs

bash read file line by line

cat myfile.lst | while read field1 field2;do echo $field1 $field2;done

comm - join like utility on linux

Compare sorted files FILE1 and FILE2 line by line.

       With  no  options,  produce  three-column  output.  Column one contains lines unique to FILE1, column two contains lines unique to FILE2, and column
       three contains lines common to both files.

ssh disable host authenticity checking

ssh -o UserKnownHostsFile=/dev/null -o StrictHostKeyChecking=no -l user 10.10.1.70

thanks to http://linuxcommando.blogspot.com/2008/10/how-to-disable-ssh-host-key-checking.html

vim open file at end

vim filename +

basic nagios bash service check

#!/bin/bash

CMD=`some command with a numerical output`

# Sanity check
if [ $# -ne 4 ]; then
        echo "Usage: $0 -w WARNING -c CRITICAL"
        exit
fi


while getopts ":w:c:" optname
  do
    case "$optname" in
      "w")
        WARNING=$OPTARG
        ;;
      "c")
        CRITICAL=$OPTARG
        ;;
      "?")
        echo -e "Unknown option $OPTARG\nUsage: $0 -w WARNING -c CRITICAL"
        ;;
      ":")
        echo "No argument value for option $OPTARG"
        ;;
      *)
      # Should not occur
        echo "Unknown error while processing options"
        ;;
    esac
  done

E_SUCCESS="0"
E_WARNING="1"
E_CRITICAL="2"
E_UNKNOWN="3"

if [ "$CMD" -gt "$CRITICAL" ]; then
        echo -n "CRITICAL"
        RETCODE=$E_CRITICAL
elif [ "$CMD" -gt "$WARNING" ];then
        echo -n "WARNING"
        RETCODE=$E_WARNING
else
        echo -n "OK"
        RETCODE=$E_SUCCESS
fi

echo "|RESULT=$CMD"
exit $RETCODE

postgres add user

1. useradd user1

2. vi /var/lib/pgsql/data/pg_hba.conf

#add the user the user ip address with authentication like this

host    all         all         10.1.19.12/32           md5

3. su - postgres

createuser user1

3. last step is to add the user to the db

alter user user1 with encrypted password 'XXXXXX';

4. grant all on tablex to user1 
or run these on the db
select 'grant all on '||schemaname||'.'||tablename||' to bar;' from pg_tables where schemaname in ('public') order by schemaname, tablename;