Have you ever made a mistake and changed permissions of the folder and all it’s subfolders? And how to change back permissions of files/folders to default state ?

Yesterday , I accidentally changed / (ROOT) permission to 777 with following command

# chmod 777 -R /

After that, All files and folders on my server changed to 777 permissions. And I try to reboot my server, I can’t login into my server. It’s shown error:

Failed to start SSH server : Starting sshd:WARNING: UNPROTECTED PRIVATE KEY FILE! Permissions 0775 for '/etc/ssh/ssh_host_key' are too open. It is recommended that your private key files are NOT accessible by others. This private key will be ignored. bad permissions: ignore key: /etc/ssh/ssh_host_key Could not load host key: /etc/ssh/ssh_host_key
...

How do I fix it ?

If you can boot your system into Single User Mode, then type 2 commands

# for p in $(rpm -qa); do rpm --setperms $p; done
# for p in $(rpm -qa); do rpm --setugids $p; done

Above command combination will reset all the permissions to the default permissions under CentOS / RHEL / Fedora Linux.

If you can’t boot into Single User Mode, Let boot from CentOS installation CD into Recuse Mode, make sure that your system mounted into /mnt/sysimage, And type the following command

# chmod 7777 -R /mnt/sysimage/

Note: Permission is 7777 not 777
To change all files and folder to “7777” permission. And reboot your system. After that, You can boot into Single User Mode and type above commands.

Reset default permissions of all files and folders under /home/

Type the following commands

# cd /home/
# for p in $(ll); do chown $p.$p -R /home/$p; done
# find . -type d -print0 | xargs -0 chmod 755
# find . -type f -print0 | xargs -0 chmod 644
# chmod 700 *

Reset default permissions of all files and folders of MySQL (/var/lib/mysql)

Type the following commands

# chown mysql.mysql -R /var/lib/mysql
# cd /var/lib/mysql
# find . -type d -print0 | xargs -0 chmod 700
# find . -type f -print0 | xargs -0 chmod 660
# chmod 777 *.sock

Finally, restart MySQL with following command

# /etc/init.d/mysqld restart

The post How To Restore Default Permissions Of All Files Under / (ROOT) appeared first on lifeLinux: Linux Tips, Hacks, Tutorials, Ebooks.

In a previous article called “Install MongoDB on Centos / RedHat“, I introduced how install MongoDB using binary package. In this article, i’ll introduce you to install MongoDB using yum command.

The first, you need add the appropriate repo. Login root and type the following command

# vi /etc/yum.repos.d/mongodb.repo

Add the following content if you are using 32 bit

[10gen]
name=10gen Repository
baseurl=http://downloads-distro.mongodb.org/repo/redhat/os/i686
gpgcheck=0

For 64 bit

[10gen]
name=10gen Repository
baseurl=http://downloads-distro.mongodb.org/repo/redhat/os/x86_64
gpgcheck=0

To install the new MongoDB packages, type the following command

# yum install mongo-10gen mongo-10gen-server

Type the following command to start MongoDB

# /etc/init.d/mongod start

Turn on MongoDB when system startup

# chkconfig mongod on

The post Install MongoDB on Linux Using Yum Command appeared first on lifeLinux: Linux Tips, Hacks, Tutorials, Ebooks.

MongoDB (from “humongous”) is an open source, high-performance, schema-free, document-oriented database written in the C++ programming language. The database is document-oriented so it manages collections of JSON-like documents. Many applications can thus model data in a more natural way, as data can be nested in complex hierarchies and still be query-able and indexable.

Install MongoDB

Download the latest binaries from mongodb.org. When downloading MongoDB, ensure that you download a version that is compiled for the proper system architecture. (Please note that the 32-bit version of MongoDB has a database size limit of 2 gigabytes).

# wget http://fastdl.mongodb.org/linux/mongodb-linux-x86_64-1.8.2.tgz
# tar zxvf mongodb-linux-x86_64-1.8.2.tgz
# mv mongodb-linux-x86_64-1.8.2 /mongodb

Create folder /mongodb/data, it’s used to store all data in MongoDB

# mkdir /mongodb/data

Create the file /mongodb/config and use the following example as a template:

dbpath = /mongodb/data
logpath = /mongodb/mongodb.log
logappend = true
bind_ip = 127.0.0.1
port = 27017
fork = true
auth = true

Create two scripts to start or stop the MongoDB process. To create start script, type the following command

# vi /mongodb/bin/start

Add the following content

#!/bin/sh
/mongodb/bin/mongod --config /mongodb/config \

Create stop script

# vi /mongodb/bin/stop

Add the following content

#!/bin/bash
pid=`ps -o pid,command ax | grep mongod | awk '!/awk/ && !/grep/ {print $1}'`;
if [ "${pid}" != "" ]; then
    kill -2 ${pid};
fi

Set execute permission

# chmod +x /mongodb/bin/start
# chmod +x /mongodb/bin/stop

After, create init script which provides a means for ensuring that MongoDB will start at boot. Type the following command

# vi /etc/init.d/mongodb

Add the following content

#! /bin/sh
#
# mongodb – this script starts and stops the mongodb daemon
#
# chkconfig: - 85 15
# description: MongoDB is a non-relational database storage system.
# processname: mongodb
# config: /opt/config/mongodb
# pidfile: /opt/mongodb/mongo.pid

PATH=/mongodb/bin:/sbin:/bin:/usr/sbin:/usr/bin
NAME=mongodb

test -x $DAEMON || exit 0

set -e

case "$1" in
  start)
        echo -n "Starting MongoDB... "
        su - mongodb -c "/mongodb/bin/start"
        ;;
  stop)
        echo -n "Stopping MongoDB... "
        /mongodb/bin/stop
        ;;
      *)
            N=/etc/init.d/$NAME
            echo "Usage: $N {start|stop}" >&2
            exit 1
            ;;
    esac
exit 0

Install PHP Driver

Once Mongo is installed we need to install the appropriate extension so that we can begin using it from within PHP. Luckily we can find the mongo extension through pecl.

# pecl install mongo

Or you can also compile Mongo driver from the latest source code on Github

# yum install php53-devel
# wget https://github.com/mongodb/mongo-php-driver/tarball/master
# tar zxvf mongodb-mongo-php-driver-*.tar.gz
# cd mongodb-mongo-php-driver-*
# phpize
# ./configure
# make install

Ater that, to load the extension on PHP startup, type the command

# echo "extension=mongo.so" >> /etc/php.ini

The post Install MongoDB on Centos / RedHat appeared first on lifeLinux: Linux Tips, Hacks, Tutorials, Ebooks.