BASH script to delete older files

# BASH Script to find files having Modification time older than 7 days and to remove.
# A provisional confirmation before deletiion has been included
# System files starting with "." in their names are excluded from deletion
# And exclusive files that are specifies in the exclusion list are prevented from being deleted

#!/bin/bash
DIR=/home/hari
LIST=/home/hari/DELETE_LIST
EXCLUSIONS=/home/hari/EXCLUSIONS

# Simply the below command will do it
# find $DIR -type f -mtime +7 | grep ^./ | grep -v -f $EXCLUSIONS -exec rm {} \;
# But for the time being it run on a CONFIRMATION before deleting the files.

#Declaration for CONFIRM()
CONFIRM()
{
echo "Going to remove $1"
echo "Do you want to Continue? -y/n"
read CHOICE
if [ $CHOICE = 'y' ]
then
rm -f $1
elif [ $CHOICE = 'n' ]
then
exit
else
echo Invalid choice
exit
fi
}
# Function FIND_FILES
FIND_FILES()
{
cd $DIR
find -type f -mtime +7 | grep ^./ | grep -v -f $EXCLUSIONS > $LIST
for i in `cat $LIST`
do
CONFIRM $ENTRY
done
}


# Call to main function FIND_FILES()
FIND_FILES
exit

Install Linux from a remote machine

This comes into picture when one Admin doesn't have physical access to a system in which Linux needs to be installed. Here we need help from one person who is having physical access to that remote machine to get it booted from bootable media and to type the command shown below command at boot prompt.


Now anaconda will start to run and will pause at a particular moment showing the below message


Now try to telnet to this IP from a remote machine and proceed with installation steps as usual as we do as shown below

How to disable a specific command(s) for a certain user.

Please follow the below steps to disable a specific command(s) for a certain user.

# su - hari
$ which rm (Here rm command as an example)
$ mkdir ~/bin
$ ln -s /bin/* ~/bin/ (/bin is the PATH for rm)
$ rm -rf ~/bin/rm

Take the output of $PATH for this user

$ echo $PATH > MyPATH.txt
Edit this file and replace /bin with ~/bin

Login as root

$ su -
# cat /home/hari/MyPATH.txt >> /home/hari/.bashrc

Change the permission of /home/hari/.bashrc
# chmod 444 /home/hari/.bashrc
# chattr +i /home/hari/.bashrc


That's all.
But the user can reset the PATH variable anytime to overcome this.
Please comment with alternatives for this.

Disable Media Check for cdrom

Grub.conf
dma=off apci=off apm=off

/etc/hdparm.conf
command_line {
hdparm -d1 /dev/cdrom
}

command_line {
hdparm -d1 /dev/cdrom1
}

sysctl.conf
dev.cdrom.check_media = 0

MySQL Compilation

# groupadd mysql
# useradd -g mysql -c "MySQL Server" mysql
# tar zxf mysql-5.0.45.tar.gz
# cd /usr/local/src/ mysql-5.0.45
# .chown -R root.root *
# ./configure \--prefix=/usr/local/mysql \--localstatedir=/usr/local/mysql/data \--disable-maintainer-mode \--with-mysqld-user=mysql \--with-unix-socket-path=/tmp/mysql.sock \--without-comment \--without-debug \

# groupadd mysql
# useradd -g mysql -c "MySQL Server" mysql
# tar zxf mysql-5.0.45.tar.gz
# cd /usr/local/src/ mysql-5.0.45
# chown -R root.root *
# ./configure \--prefix=/usr/local/mysql \--localstatedir=/usr/local/mysql/data \--disable-maintainer-mode # \--with-mysqld-user=mysql \--with-unix-socket-path=/tmp/mysql.sock \--without-comment \--without-debug \--without-bench
# make && make install
# ./scripts/mysql_install_db
# chown -R root:mysql /usr/local/mysql
# chown -R mysql:mysql /usr/local/mysql/data
# cp support-files/my-medium.cnf /etc/my.cnf
# chown root:sys /etc/my.cnf
# chmod 644 /etc/my.cnf
# echo "/usr/local/mysql/lib/mysql" >> /etc/ld.so.conf
# ldconfig
# cp ./support-files/mysql.server /etc/rc.d/init.d/mysql
# chmod +x /etc/rc.d/init.d/mysql
# /sbin/chkconfig --level 3 mysql on
# cd /usr/local/mysql/bin
# for file in *; do ln -s /usr/local/mysql/bin/$file /usr/bin/$file;

# /etc/init.d/mysql start

Open multiple tabs with Gnome-Tminal

gnome-terminal --geometry=125x75 --tab -e "ssh
192.168.0.67 -l myuser" --tab -e "ssh
192.168.0.45 -l root" --tab -e "ssh 192.168.0.88 -l
root" --tab -e "ssh 192.168.1.145 -l root -p 22999"

Set date from CLI

# date 030710532008
date
Fri Mar 7 10:53:01 IST 2008