If you have a local script file and want to run the script on another server use the following :
ssh root@torino.maranello.local ‘bash -s’ < script_local.sh
Enjoy 🙂
Cool way to run a script on a remote machine
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Amazon EC2 Docs and locations
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To work with command line on the Amazon Cloud you need to get hold of the following file which is the EC2-api-tools look for the latest version here :
I used the file found here.
When trying to setup the Amazon EC2 tools you would expect to have some script that asks you key questions and sets up the environment for you.
Well not quite so.
Starting Point is here : Setting Up the Amazon EC2 Command Line Tools
1) Install the Java JDK (Java Development Kit) OR RTE ( Run Time Engine ) found here. For cento select the rpm.
13:30:16-root@controller:~$ yum install jre-7u9-linux-i586.rpm
2) Test the java installation
13:36:56-root@controller:~$ java -version
java version “1.7.0_09”
Java(TM) SE Runtime Environment (build 1.7.0_09-b05)
Java HotSpot(TM) Client VM (build 23.5-b02, mixed mode, sharing)
3) Download and unpack the api tools
13:38:39-root@controller:/tmp$ wget “http://s3.amazonaws.com/ec2-downloads/ec2-api-tools.zip”
13:39:49-root@controller:/tmp$ unzip ec2-api-tools.zip
4) Move it to the user home folder under a new folder e.g. ec2
13:39:52-root@controller:/$ mv /tmp/ec2-api-tools-1.6.4/ ~/ec2/
5) Create a softlink to the new version (used for rewiring later when new versions are installed)
13:39:53-root@controller:/$ ln -s ~/ec2/ec2-api-tools-1.6.4/ ~/ec2/api
Create a shell script with the following environment parameters to tell amazon where the stuff is and who you are:
I add this script to my /etc/profile.d/ec2 since only two users on this machine is me :).
#!/bin/bash export JAVA_HOME=/usr export EC2_HOME=/root/ec2/api export PATH=$PATH:$EC2_HOME/bin export AWS_ACCESS_KEY=XXXXXXXXXXX export AWS_SECRET_KEY=//XXXXXXXXXXXXXXXXX export EC2_URL=https://ec2.eu-west-1.amazonaws.com
Other Documents :
Screen utility not processing the ~/.bash_profile
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After you build your custom ~/.bash_profile when you use screen it skips the customizations in the ~/.bash_profile file.
Try to edit .screenrc and then add
shell -$SHELL
Adding a XFS filesystem to CentOS 5
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Howto use enterprise Linux ‘extras’ to mount a XFS filesystem on a CentOS v5.2 VM
Install RPM’s
Note: Due to this bug (3205), install binutils to overcome the error “xargs: nm: No such file or directory” while installing kmod-xfs-xen.
# yum install binutils
# yum install xfsprogs yum-kmod kmod-xfs-xen
# mkfs.xfs -f /dev/sda1
Check
A chunk of disk (2TB) has been allocated to a LVM partition for the VM, which is formatted with XFS. The device is mapped into the VM as /dev/xvdc1 (i.e. a whole device, c.f. partitioned device).
Before using the filesystem, perform a check:
# xfs_check /dev/xvdc1
Note: xfs_check requires a significant chunk of memory to run. With 2Gbyte of swap and 1Gbyte of RAM a check was unsuccessful.
Mount
Mount the disk by using it’s volume label. The label can be verified with the xfs_admin program:
# xfs_admin -l /dev/xvdc1
label = “purple-files”
Add the mount entry to ‘/etc/fstab’ so that the filesystem is automatically mounted at the next restart.
LABEL=purple-files /files xfs defaults 0 0
Mount the filesystem
# mount /files
NOTE: CENTOS 6.X
Centos 6.X (64bit) already supports XFS in kernel. You only need to install xfsprogs package to mount xfs filesystems. just yum install xfsprogs (it is included in centos 6.2 base)
Appendices
# yum install xfsprogs yum-kmod kmod-xfs-xen
Dependencies Resolved
=============================================================================
Package Arch Version Repository Size
=============================================================================
Installing:
kmod-xfs-xen x86_64 0.4-2 extras 256 k
xfsprogs x86_64 2.9.4-1.el5.centos extras 1.3 M
yum-kmod noarch 1.1.10-9.el5.centos base 15 k
Transaction Summary
=============================================================================
Install 3 Package(s)
Update 0 Package(s)
Remove 0 Package(s)
Total download size: 1.6 M
Search entire filesystem for text in Linux
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To search for text through the entire filesystem from the current path down in Linux use the following :
find / -type f -print0 | xargs -0 grep -l "string to search" 2>/dev/null
Script to list all the MAC addresses on the system
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Listing the mac addresses of nic cards excluding null or loopback MACs i.e. 00:00:00:00:00:00
grep -H . /sys/class/net/*/address | awk ‘{split($0,array,”address:”);print array[2]}’ | grep -v ’00:00:00:00:00:00′
Force fsck on next boot
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Since live systems are near to impossible to fsck when running (unless you can pull one side of the mirror then clone it to the other (very messy).
Become Root
sudo su –
or
su –
As root create file in root folder a file named forcefsck
touch /forcefsck
Restart the system.
shutdown -r now
Using .htaccess to redirect a page with permanently moved 301
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Though there are many ways to redirect using the HTTP 301 status code.
(make sure the AllowOverride is set to all on the apache config)
The .htaccess must be as follows:
Options +FollowSymlinks
RewriteEngine on
rewritecond %{http_host} ^orig.domain.com [nc]
rewriterule ^(.*)$ http://new.domain.com/
$1 [r=301,nc]
Replace the orig.domain.com and new.domain.com with the ones needed for your case of course.
You can setup logs for checking the rewriting though be warned enable them only when debugging they are hugely intensive on I/O and CPU on a heavy utilised server.
More info here : http://httpd.apache.org/docs/2.2/mod/mod_rewrite.html#rewritelog
Nagios fail to run ifstatus
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/usr/local/nagios/libexec/check_ifstatus -H localhost
 
Can’t locate Net/SNMP.pm in @INC (@INC contains: /usr/local/nagios/libexec /usr/local/lib/perl5 /usr/local/share/perl5 /usr/lib/perl5/vendor_perl /usr/share/perl5/vendor_perl /usr/lib/perl5 /usr/share/perl5 .) at ./check_ifstatus line 38.
BEGIN failed–compilation aborted at ./check_ifstatus line 38.
Solution:
yum install perl-Net-SNMP
Nagios configuration debugging
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After testing a nagios configuration update ( including a new service or renaming some host etc..) before committing the changes and reloading / restarting the nagios service a good test is the following:
/usr/local/nagios/bin/nagios -v /usr/local/nagios/etc/nagios.cfg
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