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Showing posts from March, 2017

Procedure to Reduce the Logical Volume

Scenario :   Suppose we want to reduce  /home  by 2GB which is LVM and formated as  ext4. [root@cloud ~]# df -h /home/ Filesystem            Size  Used Avail Use% Mounted on /dev/mapper/vg_cloud-LogVol00 12G  9.2G  1.9G  84% /home Step:1 Umount the filesystem [root@cloud ~]# umount /home/ Step:2 check the filesystem for Errors using e2fsck command. [ root@cloud ~]# e2fsck -f /dev/mapper/vg_cloud-LogVol00 e2fsck 1.41.12 (17-May-2010) Pass 1: Checking inodes, blocks, and sizes Pass 2: Checking directory structure Pass 3: Checking directory connectivity Pass 4: Checking reference counts Pass 5: Checking group summary information /dev/mapper/vg_cloud-LogVol00: 12/770640 files (0.0% non-contiguous), 2446686/3084288 blocks Note:  In the above command  e2fsck  , we use the option  ‘-f’  to forcefully check the filesystem , even if the filesystem is clean. Step...

Comparing temporary and Persistant routes in Linux

Hi This script will help us to compare the routes which is persistent and which is not. ################################################################################# #!/bin/bash  ifconfig | grep addr | awk '{print $1}' > /tmp/interfaces && sed -i.bak_$time "s/inet6*//g" /tmp/interfaces  for i in $(cat /tmp/interfaces);  do  echo "******* Verifying routes on $i interface ********"  cp /etc/sysconfig/network-scripts/route-$i /tmp/route-$i  route -n | grep -i $i | grep -i ug  |awk '{print $1}' > /tmp/currentroutes  echo "***** Comparing Current and Persistant Routes on $i *****" for j in $(cat /tmp/currentroutes);          do          cat /tmp/route-$i | grep $j     if [ $? == 0 ]     then echo "***** route $j is persistent on $(hostname) *****"     else echo "#### route $j is not persistent on $(hostname) on $i ####"   ...

Crontab entries

Linux Crontab Format MIN HOUR DOM MON DOW CMD Table: Crontab Fields and Allowed Ranges (Linux Crontab Syntax) Field Description Allowed Value MIN Minute field 0 to 59 HOUR Hour field 0 to 23 DOM Day of Month 1-31 MON Month field 1-12 DOW Day Of Week 0-6 CMD Command Any command to be executed. 1. Scheduling a Job For a Specific Time The basic usage of cron is to execute a job in a specific time as shown below. This will execute the Full backup shell script (full-backup) on  10th June 08:30 AM . Please note that the time field uses 24 hours format. So, for 8 AM use 8, and for 8 PM use 20. 30 08 10 06 * /home/ramesh/full-backup 30  – 30th Minute 08  – 08 AM 10  – 10th Day 06  – 6th Month (June) *  – Every day of the week 2. Schedule a Job For More Than One Instance (e.g. Twice a Day) The following script take a incremental backup twice a day every day. This example executes the specified incremental backup shell script (incremental-...